Articles de revues : « Natural and artificial ageing »

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Røyset, Jostein, Tore Stene, Jan Anders Sæter et Oddvin Reiso. « The Effect of Intermediate Storage Temperature and Time on the Age Hardening Response of Al-Mg-Si Alloys ». Materials Science Forum 519-521 (juillet 2006) : 239–44. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.239.

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Specimens of three Al-Mg-Si alloys, 6060, 6005 and 6082, were solution heat treated, stored at different temperatures for different time, and artificially aged. Properties were measured before and after artificial ageing. The natural ageing response of the alloys is dependent on the storage temperature. Decreasing storage temperature leads to a delayed onset of natural ageing, but also to a higher strength after prolonged ageing, particularly for lean alloys such as 6060. The temperature and time of intermediate storage between solution heat treatment and artificial ageing has a significant effect on the strength of the artificially aged material. For the 6005 and 6082 alloys the processes that take place during natural ageing lead to a reduced strength after artificial ageing.

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Zhang, Xingpu, Meng Liu, Jiangwei Wang, Jixue Li et John Banhart. « Combined effect of Sn addition and pre-ageing on natural secondary and artificial ageing of Al–Mg–Si alloys ». Journal of Materials Science 57, n^o 3 (janvier 2022) : 2149–62. http://dx.doi.org/10.1007/s10853-021-06654-y.

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AbstractBoth Sn addition and pre-ageing are known to be effective in maintaining the artificial ageing potential after natural ageing of Al–Mg–Si alloys. In this study, the combined effects of Sn addition and pre-ageing at 100 °C or 180 °C on natural secondary ageing and subsequent artificial ageing of an alloy AA6014 were investigated using hardness, electrical resistivity, differential scanning calorimetry and transmission electron microscopy characterizations. It is found that pre-ageing can suppress natural secondary ageing and improve the artificial ageing hardening kinetics and response after 1 week of natural secondary ageing in both alloys with and without Sn addition. The effect of pre-ageing at 100 °C is more pronounced in the Sn-free alloy while the combination of pre-ageing at 180 °C and adding Sn shows superiority in suppressing natural secondary ageing and thus avoiding the undesired hardening before artificial ageing. Moreover, when natural ageing steps up to 8 h are applied before pre-ageing at 100 °C, the effect of pre-ageing in Sn-added alloy can be further improved. The influence of Sn on vacancies at different ageing temperatures is discussed to explain the observed phenomena. Graphical abstract

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Aze, Sébastien Vallet, Alain Baronnet et Olivier Grauby. « Red lead darkening in wall paintings : natural ageing of experimental wall paintings versus artificial ageing tests ». European Journal of Mineralogy 19, n^o 6 (17 décembre 2007) : 883–90. http://dx.doi.org/10.1127/0935-1221/2007/0019-1771.

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Laurenzi Tabasso, Marisa, et Anna María Mecchi. « Envejecimiento natural y artificial para evaluar los tratamientos para impermeabilización del mármol ». Materiales de Construcción 42, n^o 226 (30 juin 1992) : 5–25. http://dx.doi.org/10.3989/mc.1992.v42.i226.700.

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Tai, Cheng-Ling, Po-Jui Tai, Ting-Jung Hsiao, Po-Han Chiu, Chien-Yu Tseng, Tzu-Ching Tsao, Tsai-Fu Chung et al. « Effect of Natural Ageing on Subsequent Artificial Ageing of AA7075 Aluminum Alloy ». Metals 12, n^o 10 (20 octobre 2022) : 1766. http://dx.doi.org/10.3390/met12101766.

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The effects of natural ageing treatment prior to artificial ageing treatment on the microstructures and mechanical properties of AA7075 Al-5.7Zn-2.6Mg-1.5Cu-0.18Cr-0.08Mn-0.05Si-0.17Fe (wt.%) aluminum alloy have been investigated. The hardness of solution-treated samples (91.0 HV) profoundly increased to 146.8 HV after 7 days of natural ageing. The purpose of the present work was to examine the kinetic hardening evolution in subsequent artificial ageing treatments of samples naturally aged for 7 days and their counterparts without natural ageing. The former were labelled as NA-7d samples, and the latter, NA-0d samples. After artificial ageing at 120 °C for 2 h, the hardness of NA-0d samples increased rapidly to 148.2 HV, which was approximately the same as that of the specimens with natural ageing for 7 days, compensating for the prior state of lower hardness without natural ageing. After being treated at 120 °C for 16 h, the ultimate tensile strength (UTS) and yield strength (YS) of NA-7d reached the highest value, respectively, 601 MPa and 539 MPa, followed by a slight decrement of UTS when aged to 24 h. On the other hand, NA-0d specimens aged at 120 °C for 16 and 24 h showed nearly the same UTS (598 MPa); the former possessed YS of 538 MPa, and the latter, 545 MPa. The results presumably reveal that the peak ageing condition for NA-0d samples can be achieved under 24 h ageing at 120 °C. Under the same treatment at 120 °C for 24 h, the size of η’ phase in NA-7d sample (with a length of 4.96 nm) coarsened and grew larger than that in NA-0d sample (with a length of 3.46 nm). In addition, some η’ phase in the NA-7d sample was found to be transformed into the η2 phase. The results indicated that the naturally aged specimens (NA-7d) reached the peak ageing condition earlier, but did not significantly enhance the UTS in AA7075 aluminum alloy, as compared to the samples without prior natural ageing (NA-0d).

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Cao, Ling Fei, Paul A. Rometsch, Hao Zhong et Barry C. Muddle. « Effect of Pre-Ageing on the Artificial Ageing Response of Al-Mg-Si(-Cu) Alloys ». Materials Science Forum 654-656 (juin 2010) : 918–21. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.918.

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The effect of different pre-ageing treatments on the subsequent artificial ageing response of Al-Mg-Si(-Cu) alloys have been investigated using hardness, tensile and electrical conductivity testing. The microstructural evolution was characterised by differential scanning calorimetry (DSC) and 3-dimensional atom probe (3DAP) analysis. Pre-ageing treatments were carried out at 160-250°C for short times. Results show that the early stage artificial ageing response after 30 minutes at 170°C is strongly influenced by the pre-ageing and natural ageing conditions. A pre-ageing treatment performed for a short time at a high temperature and within a short delay after solution treatment and quenching was found to give a promising hardening response during subsequent artificial ageing. The mechanisms by which pre-ageing can reduce the detrimental effect of natural ageing on the artificial ageing response will be discussed in relation to the formation and distribution of clusters, GP zones and/or precipitates.

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Volk, Gregor, Alan G. Leacock et Desmond Brown. « Profile Correction of a Stretch Formed Aluminium Alloy during Artificial Ageing ». Key Engineering Materials 549 (avril 2013) : 213–19. http://dx.doi.org/10.4028/www.scientific.net/kem.549.213.

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A method of springback reduction is presented which involves a combination of solution heat treatment, natural ageing, stretch forming and artificial ageing. A commercial aluminium alloy, 2219-O Hi-Form, is solution heat treated and subjected to two pre-form natural ageing periods of one and seven hours before the stretch forming process. Following the forming process an artificial ageing process combined with creep age forming techniques is used. Springback is assessed following the stretch forming and artificial ageing processes. This process is shown to provide a controlled means of correcting the springback following stretch forming.

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Hou, Yan Hui, Zhi Yi Liu et Yan Bin Liu. « Modeling and Analysis of Effect of Thermal Exposure on Fatigue Crack Growth of Al-Cu-Mg Alloys with Low Cu/Mg Ratio ». Advanced Materials Research 213 (février 2011) : 111–15. http://dx.doi.org/10.4028/www.scientific.net/amr.213.111.

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Effect of thermal exposure on FCG of Al-Cu-Mg alloys with low Cu/Mg ratio in artificial and natural ageing conditions were modeled and analyzed. Three FCG rate models, namely Collipriest, Priddle, and Modified Forman model were examined to research the effect of thermal exposure on FCG of Al-Cu-Mg alloys with low Cu/Mg ratio in artificial and natural ageing conditions. The results showed that Priddle model provided the best fit. Priddle model was used to fit FCG data of (a) 170°C/30min ageing; (b)170°C/30min ageing +100°C/2000h exposure; (c)T351 ageing+100°C/2000h exposure; (d)T351 ageing. The fitted results indicated that the FCP resistance can be increased by slight artificial aging, and artificial aging can delay the degradation of the fatigue properties

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Möller, Heinrich, Pfarelo Daswa et Gonasagren Govender. « The Heat Treatment of Rheo-High Pressure Die Cast 6xxx Series Al-Mg-Si-(Cu) Alloys ». Materials Science Forum 794-796 (juin 2014) : 137–42. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.137.

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Limited information is available regarding the heat treatment response of age-hardenable wrought Al-alloys produced by semi-solid metal forming. In this study, the effects of chemical composition, natural pre-ageing and artificial ageing on the T6 properties of rheo-high pressure die cast 6xxx series Al-Mg-Si-(Cu) alloys are investigated. A Cu-free alloy 6082 is compared with Cu-containing alloys 6013 and 6111. The effects of Mg:Si ratio of the alloys are also quantified by means of a comparison between alloys 6111 and 6013. Artificial ageing curves following either no or 5 days of natural pre-ageing are also presented.

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Hussain, Maruff, P. Nageswara Rao, Dharmendra Singh et R. Jayaganthan. « Effect of Pre-Ageing on the Age Hardening Response of Cryorolled Al-Mg-Si Alloy ». Applied Mechanics and Materials 877 (février 2018) : 137–48. http://dx.doi.org/10.4028/www.scientific.net/amm.877.137.

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The present work investigates about the effect of pre-ageing on hardening behavior of Al-Mg-Si alloys processed by cryorolling and its age hardening behavior. Ageing conditions were examined at natural ageing for 2days and pre-ageing at 100 °C, 130°C and 170 °C for 4 hours, 2 hours and 30 minutes respectively. The observations revealed that, the pre-ageing before cryorolling is useful to enhance the dislocation density during cryorolling. However artificial ageing of cryorolled samples is not influenced much with pre-ageing. It is revealed that, maturing at room temperature of CR samples for 30 days has resulted better hardening response during artificial ageing.

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Podgorski, L., A. Merlin et J. M. Saiter. « Natural and artificial ageing of an alkyd based wood finish ». Journal of Thermal Analysis 41, n^o 6 (juin 1994) : 1319–24. http://dx.doi.org/10.1007/bf02549926.

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Gutiérrez, Germán, Felipe Cruz, Juan Moreno, Victor A. González-Hernández et Jorge M. Vázquez-Ramos. « Natural and artificial seed ageing in maize : germination and DNA synthesis ». Seed Science Research 3, n^o 4 (décembre 1993) : 279–85. http://dx.doi.org/10.1017/s0960258500001896.

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AbstractThe effect of natural and artificial seed ageing has been compared in terms of physiological and biochemical responses of several maize genotypes. The physiological parameters were: viability, germinability, emergence in sand and dry matter accumulation. The biochemical parameters were: DNA synthesis and DNA polymerase activity. A close and direct relationship was found between seed deterioration and DNA metabolism in all maize materials which responded to ageing according to their genetic constitution; i.e., vigorous genotypes suffered less severe damage or recovery was faster than in the low-vigour genotypes. Coordination of events at appropriate times would seem a critical factor for proper seed germination.

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Banhart, John, Zi Yang, Meng Liu, Mazen Madanat, Xingpu Zhang, Qianning Guo, Yong Yan et al. « Exploring the hidden world of solute atoms, clusters and vacancies in aluminium alloys ». MATEC Web of Conferences 326 (2020) : 01001. http://dx.doi.org/10.1051/matecconf/202032601001.

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Precipitation hardening involves solutionising, quenching and annealing steps, the latter often at various temperatures. The phenomena observed in Al-Mg-Si alloys are very complicated and partially not well understood. During and after quenching, solute atoms diffuse through the lattice assisted by vacancies and form atom clusters that gradually grow. These act back onto vacancies, which complicates the situation. We apply positron annihilation techniques in addition to traditional hardness, resistivity and thermal measurements to clarify what happens in various stages of thermal treatment: The quenching process can be divided into a stage of vacancy loss and of precipitation. Very short artificial ageing treatments after heating at different rates show that there is a competition between vacancy losses and cluster formation as the temperature increases. The difference between natural ageing and artificial ageing can be defined based on the importance of excess vacancies. Based on such results the behaviour of “invisible” objects such as vacancies and small clusters can be better understood but some open question remain such as the kinetics of secondary ageing or the details of the negative effect of natural ageing on artificial ageing.

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Zhong, Hao, Bin Liao, Xiao Dong Wu, Ling Fei Cao et Paul A. Rometsch. « Development of Al-Mg-Si-(Cu) Alloys for Automotive Body Panels and the Related Ageing Behaviours ». Materials Science Forum 879 (novembre 2016) : 279–83. http://dx.doi.org/10.4028/www.scientific.net/msf.879.279.

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In this work, Al-Mg-Si-Cu alloys for automotive body panels were designed and the related ageing behaviours were discussed in detail to help understand natural ageing and pre-ageing, as well as their influence on the subsequent paint-bake response. The clustering behavior of these Al-Mg-Si-Cu alloys in different ageing conditions was investigated by hardness / yield strength and electrical conductivity testing. The microstructure was investigated by using Electron Backscattered Diffraction (EBSD) technique, along with Scanning Electron Microscopy with Backscattered Electron Detector (BSE). The results show that the paint bake response is strongly influenced by the pre-ageing and natural ageing conditions. Both alloys show serrated yielding in a short natural ageing condition. Immediate high-temperature pre-ageing treatments were found to give a promising hardening response during the subsequent artificial ageing/ paint baking at 170oC.

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López, V., E. Otero, A. Bautista, E. Escudero et J. A. González. « Changes in the morphology of porous anodic films formed on aluminium in natural and artificial ageing ». Revista de Metalurgia 39, Extra (17 décembre 2003) : 104–9. http://dx.doi.org/10.3989/revmetalm.2003.v39.iextra.1105.

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Bahrami, Abbas, et Maryam Yazdan Mehr. « Modeling Electrical Resistivity of Naturally Aged Al–Mg–Si Alloys ». Metals 9, n^o 3 (8 mars 2019) : 310. http://dx.doi.org/10.3390/met9030310.

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Isothermal ageing of Al–Mg–Si alloys, stored at room temperature for more than 5 months, is associated with an unexpected significant increase in the overall electrical resistivity. This unexpected anomalous increase is not observed in alloys with shorter storage (natural ageing) times. This phenomenon is explained with a scenario, based on the evolution of the size distribution of Guinier–Preston (GP) zones during natural ageing and during subsequent artificial ageing. The proposed scenario can explain the contribution of natural ageing atomic clusters to this anomalous increase in the electrical resistivity. A physically based combined precipitation–electrical resistivity model, with the former being based on simultaneous nucleation-growth-coarsening reactions and the latter based on the Bragg scattering of electrons from atomic clusters, has been used to explain the electrical resistivity evolution. It is shown that the proposed model is capable of reproducing the experimental data in both short natural ageing (less than 5 months) and long natural ageing (more than 5 months) regimes.

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Morley, A. I., M. W. Zandbergen, Alfred Cerezo et George D. W. Smith. « The Effect of Pre-Ageing and Addition of Copper on the Precipitation Behaviour in Al-Mg-Si Alloys ». Materials Science Forum 519-521 (juillet 2006) : 543–48. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.543.

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Hardness measurements and 3-dimensional atom probe analysis have been used to characterise the precipitation behaviour in two 6xxx series aluminium alloys, one Cu-free alloy (Al-0.78at%Mg- 0.68at%Si) and one Cu-containing alloy (Al-0.78at%Mg-0.68at%Si-0.30at%Cu). The heat treatments consisted of either natural ageing or pre-ageing at 353K followed by a paint-bake treatment at 453K. Natural ageing was seen to increase the hardness, and hence reduce formability compared to pre-ageing. In addition, the strengthening effect of artificial ageing was less after natural ageing than after pre-ageing. In the Cu-free alloy, needle-like β″ was observed to form only after a pre-ageing treatment during the first 60 minutes of a paint-bake treatment. In the Cucontaining alloy, needle-like β″ formed during paint bake in both the naturally-aged and pre-aged material, although it is formed more rapidly after pre-ageing. This was accompanied by an increase in strength over the Cu-free alloy and indicates that Cu reduces the deleterious effect of natural ageing.

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Yan, Yong, Ze Qin Liang et John Banhart. « Influence of Pre-Straining and Pre-Ageing on the Age-Hardening Response of Al-Mg-Si Alloys ». Materials Science Forum 794-796 (juin 2014) : 903–8. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.903.

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The effect of pre-straining and pre-ageing on the age hardening response of Al-0.6%Mg-0.8%Si alloy is studied by Vickers hardness and differential scanning calorimetry (DSC). It is found that pre-ageing can suppress the formation of unwanted clusters and keeps the structure stable for a certain time. A pre-ageing treatment can effectively reduce or avoid the negative effect of natural ageing on artificial ageing and even produce a positive effect. Cluster formation can also be reduced by pre-straining, but the kinetics of clustering is still similar to that of the as-quenched condition. In contrast, after pre-straining, the peak positions of β and β move to lower temperatures and peak hardness is achieved in a shorter time, indicating that the formation of β and β is accelerated by pre-straining. However, the negative effect of natural ageing still persists after pre-straining. Pre-straining before pre-aging can take advantage of both techniques and produce a positive strength response. For pre-straining after pre-aging, pre-straining tends to destabilize the structure created by pre-ageing and can reactivate the clustering process, which has negative effect on subsequent artificial ageing.

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Roveri, Marco, Sara Goidanich et Lucia Toniolo. « Artificial Ageing of Photocatalytic Nanocomposites for the Protection of Natural Stones ». Coatings 10, n^o 8 (24 juillet 2020) : 729. http://dx.doi.org/10.3390/coatings10080729.

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During the last ten years, photocatalytic nanocomposites combining titania nanoparticles with silicon-based matrices have received increasing attention in the stone conservation research field, because they offer an effective multifunctional approach to the issue of stone protection. However, much work still has to be done in studying the behaviour of these nanocomposites in real environmental conditions and understanding to what extent they are able to retain their effectiveness and compatibility once applied on outdoor surfaces. The latter is a key information that should lie at the basis of any successful conservation and maintenance campaign. The present study provides insight into this relevant topic trough laboratory testing by assessing the artificial ageing of two silane-based photocatalytic nanocomposites, previously selected through an accurate testing on different natural stones. Three accelerated ageing procedures, based on artificial solar irradiation, heating and rain wash-out, allowed simulating about two years of outdoor exposure to some of the weathering factors to which stones are normally subjected. The results provided quite accurate information about the long-term behaviour of the products and on the role that the stone properties play therein. It was shown that, when the products are able to penetrate deeply enough inside the stone pores, they retain much of their hydrophobising and photocatalytic properties and maintain a good compatibility with the stone substrates, even after partial chemical degradation of the alkyl-silica matrices has occurred on the very stone surface.

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Łojewski, Tomasz, Paweł Miśkowiec, Marcin Molenda, Anna Lubańska et Joanna Łojewska. « Artificial versus natural ageing of paper. Water role in degradation mechanisms ». Applied Physics A 100, n^o 3 (8 avril 2010) : 625–33. http://dx.doi.org/10.1007/s00339-010-5645-9.

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MITRAN, Elena-Cornelia, Irina-Mariana SANDULACHE, Lucia-Oana SECAREANU, Ovidiu IORDACHE, Elena PERDUM et Maria MEMECICA. « EFFECTS OF ARTIFICIAL AGEING ON TEXTILES' PROPERTIES ». TEXTEH Proceedings 2019 (5 novembre 2019) : 132–35. http://dx.doi.org/10.35530/tt.2019.28.

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In the present paper work it was evaluated the degradation degree of textile material after different types of exposure using micro-destructive methods such as: Scanning Electron Microscopy (SEM), stereomicroscope and Datacolor spectrophotometer. Thus, samples of cotton fabrics were exposed in three different methods: first – outdoors, to natural conditions, second – at a temperature of 60⁰C in an oven and third – buried in commercial plant soil in closed recipients. After 72 hours and 216 hour, specimens of the samples were taken and evaluated. Thereby, microscopic analyzes revealed that the cotton materials are more degraded after burial. The results obtained were correlated with chromatic parameters (DL*, DC*, DE*) and white degree (Berger and CIE). All the samples have color differences in comparison with the unexposed samples; they also present more saturated color and are darker. Cultural heritage represents our history, thus it is important to know how the environment works on textile materials and this way we can manage better the conservation requirements. Future studies will also be carried out on linen and woolfabrics.

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Yang, Zi, Xiaohe Jiang, Xingpu Zhang, Meng Liu, Zeqin Liang, David Leyvraz et John Banhart. « Influence of quench rate on multi-stage ageing of AA6014 alloy ». MATEC Web of Conferences 326 (2020) : 02005. http://dx.doi.org/10.1051/matecconf/202032602005.

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The influence of quench rate after solution heat treatment on the microstructure in the as-quenched state and subsequent ageing kinetics of alloy AA6014 was investigated by means of transmission electron microscopy, positron annihilation lifetime spectroscopy and hardness measurements. Various ageing temperatures and stages were taken into consideration. Consistent with previous studies, we found that solute and vacancy supersaturation decrease during slow quenching due to precipitation and annihilation, respectively. Additionally, we observed cluster formation during cooling below 200 °C. As for the influence on ageing behaviour we observe different behaviour for high and low ageing temperature: Artificial ageing is more affected than pre-ageing and natural secondary ageing. The detrimental effect of natural ageing on paint-bake hardening also depends on the quench rate. Possible interpretations are associated with cluster formation during natural ageing and also during quenching. The influence of pre-ageing at different temperatures on subsequent ageing kinetics is similar for slower industrial-type quenching and for fast quenching, thus allowing to apply the findings from idealised quenching conditions to situations closer to real application.

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Mørtsell, Eva A., Ida Westermann, Calin D. Marioara, Ketill O. Pedersen, Sigmund J. Andersen, Jostein Røyset et Randi Holmestad. « The Effect of Elastic Straining on a 6060 Aluminium Alloy during Natural or Artificial Ageing ». Materials Science Forum 794-796 (juin 2014) : 1205–10. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.1205.

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The effect on hardness and precipitate microstructure of elastically straining a 6060 Al-Mg-Si alloy during natural ageing or artificial ageing has been investigated. The elastic strain is here defined as 50 % of the material yield strength. All heat treatments where elastic straining was applied led to an increased hardness compared to the unstrained reference material. Quantitative investigations of the precipitate microstructure using transmission electron microscopy (TEM) did not indicate any significant difference in precipitate parameters as compared to the unstrained reference material. Therefore the increased strength in the elastically strained material is being linked to strain induced dislocations based on faster ageing kinetics compared to unstrained reference samples.

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Du, Kang, Qiang Zhu et Da Quan Li. « Effects of Natural Ageing on T6 Heat Treated Rheocasts of 319S Aluminum Alloy ». Solid State Phenomena 256 (septembre 2016) : 58–62. http://dx.doi.org/10.4028/www.scientific.net/ssp.256.58.

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T6 heat treatment is an effective method to improve the comprehensive properties of Al-Si-Cu-Mg series aluminium alloys. Solution treatment temperature and time, quench process and media, as well as artificial ageing temperature and time are the key factors to determine mechanical properties. Besides these factors, natural ageing, i.e. the holding time between quenching and the starting of artificial treatment at ambient temperature was observed to be significant affect mechanical properties of the aluminium alloys. This effect on semi solid processed aluminium alloys was lack of investigations as the semi solid process produces T6 treatable and weldable components. The present paper focuses on the change regularity of hardness and precipitate behaviour of semi-solid 319S aluminium alloy under different natural ageing (NA) treatment additional to standard T6. Density and morphology of hardening precipitates are analysed using TEM, and the influence mechanism of NA during T6 heat treatment will be discussed. The results show that NA has a positive influence on mechanical properties of the rheo-cast 319S alloy.

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Schäfer, Carmen, Ole Runar Myhr, Henk Jan Brinkman, Olaf Engler et Jürgen Hirsch. « Modelling the Combined Effect of Room Temperature Storage and Cold Deformation on the Age-Hardening Behaviour of Al-Mg-Si Alloys-Part 2 ». Materials Science Forum 794-796 (juin 2014) : 722–27. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.722.

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The present investigation deals with modelling of the age-hardening behaviour of 6xxx series automotive sheet alloys. The basis for this work is the established precipitation model NaMo developed for coupled nucleation, growth, dissolution and coarsening in Al-Mg-Si extrusion alloys. It has recently been extended for applicability for Al-Mg-Si automotive sheet alloys by incorporating the important effects of room temperature (RT) storage and deformation prior to the final artificial ageing of Al-Mg-Si sheet alloys. The 6xxx automotive sheet alloys change due to natural ageing during the time elapsing between their processing and their paint baking in the customers process. This RT storage time has an impact on the artificial ageing response during the OEMs paint baking cycle. A second effect originates from the deformation introduced in the material during the part forming process prior to the artificial ageing in the paint bake cycle. This deformation leads to the introduction of dislocations which further modify the artificial ageing response by providing heterogeneous nucleation sites for nucleation of additional strengthening phases. Part 1 of this work deals with the theoretical background and experimental validation of the extended version of NaMo, while Part 2 focuses on the new applications of the extended model by simulation of ageing during paint baking according to typical customer requirements. The model validation is based on a comprehensive set of tensile tests. A comparison between model predictions and measurements shows reasonable agreement, and it is concluded that, after some further development, the model can be used to model the yield strength response of 6xxx automotive sheet alloys incorporating the (combined) effects of natural ageing, deformation and the accurate heat treatments in the paint bake cycle.

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Achitei, Dragoş Cristian, Andrei Victor Sandhu, Mohd Mustafa Al Bakri Abdullah, Petrică Vizureanu et Hussin Kamarudin. « Study on Quenching and Artificial Ageing on Al-Si Alloy ». Materials Science Forum 803 (août 2014) : 209–15. http://dx.doi.org/10.4028/www.scientific.net/msf.803.209.

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Aluminum alloys have special advantages on the structural changes induced by thermal treatments. Thus, for proper machining a solution quenching is applied, when the hardness and the tensile strength of the alloy decreases. In order to restore the properties natural or artificial ageing is necessary.

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Shen, C. H., et B. L. Ou. « Effect of Prestraining on the Natural Ageing and Artificial Ageing of an Al-Mg-Si Alloy AA6022 ». Canadian Metallurgical Quarterly 46, n^o 1 (mars 2007) : 65–74. http://dx.doi.org/10.1179/cmq.2007.46.1.65.

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Yakovleva, E. A., A. V. Larionov, G. D. Motovilina et E. I. Khlusova. « Effect of natural and artificial ageing on steel mechanical properties and fracture toughness ». Voprosy Materialovedeniya, n^o 3(107) (3 décembre 2021) : 28–39. http://dx.doi.org/10.22349/1994-6716-2021-107-3-28-39.

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The operating conditions of welded structures of shipbuilding steels, including operation at northern latitudes, determine high requirements for their quality. Materials used for such structures should guarantee stable mechanical properties, good processability during hull fabrication and serviceability at subzero temperatures. Strain aging is due to the thermodynamic non-equilibrium of steel structure in its initial state and gradual transition to the equilibrium state provided the diffusion mobility of interstitial atoms is sufficient. In unfavorable conditions, this can lead to the degradation of properties during processing (cold straightening, bending, welding), operation or long-term storage. The paper studies the probability of natural and artificial ageing processes in steels of different chemical compositions due to bulk diffusion and carbon dislocation core diffusion (dislocation pipe diffusion). The effect of strain ageing on mechanical properties and the CTOD parameter value has been examined.

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Yang, Zi, et John Banhart. « Natural and artificial ageing in aluminium alloys – the role of excess vacancies ». Acta Materialia 215 (août 2021) : 117014. http://dx.doi.org/10.1016/j.actamat.2021.117014.

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Kennedy, K., R. Cal, R. Casey, C. Lopez, A. Adelfio, B. Molloy, A. M. Wall, T. A. Holton et N. Khaldi. « The anti‐ageing effects of a natural peptide discovered by artificial intelligence ». International Journal of Cosmetic Science 42, n^o 4 (20 juillet 2020) : 388–98. http://dx.doi.org/10.1111/ics.12635.

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Fredj, N., S. Cohendoz, X. Feaugas et S. Touzain. « Ageing of marine coating in natural and artificial seawater under mechanical stresses ». Progress in Organic Coatings 74, n^o 2 (juin 2012) : 391–99. http://dx.doi.org/10.1016/j.porgcoat.2011.10.002.

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Chauke, Levy, Pfarelo Daswa, Heinrich Möller et Gonasagren Govender. « The Effect of Natural Pre-Ageing on the Mechanical Properties of Rheo-High Pressure Die Cast Aluminium Alloy 2139 ». Materials Science Forum 828-829 (août 2015) : 244–49. http://dx.doi.org/10.4028/www.scientific.net/msf.828-829.244.

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Near-net shape casting of wrought aluminium alloys has proven to be difficult due to hot tearing. The Council for Scientific and Industrial Research (CSIR) has successfully processed wrought aluminium alloy 2139 into plate castings using the Rheo-high pressure die casting process (R-HPDC). Alloy 2139 is a Ag-containing aluminium alloy from the Al-Cu-Mg 2xxx series family. The addition of Ag enhances the age hardening response through the formation of co-clusters that act as precursors to the formation of plate-like Ω precipitates. These co-clusters typically form during natural ageing and 12-24 h of natural pre-ageing is normally specified before artificial ageing in Ag-containing Al-Cu-Mg alloys. The T6 hardness and tensile properties of R-HPDC 2139 alloy were investigated with and without natural pre-ageing. It is shown that there is no significant difference in both peak hardness and tensile properties in R-HPDC alloy 2139 with and without natural pre-ageing. The possible precipitation phenomena in both cases are discussed.

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Baruah, Monoj, et Anil Borah. « Effect of Solution Treatment on Ageing Behaviour of Al-Mg-Si-Sn Alloy ». Advanced Engineering Forum 39 (février 2021) : 1–8. http://dx.doi.org/10.4028/www.scientific.net/aef.39.1.

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In this study both natural ageing (NA) and artificial ageing (AA) behaviour of Al-Mg-Si aluminium alloy having trace addition of 0.04 wt.% Sn (Tin) was studied at different solution heat treatment (SHT) temperature and time, ageing time and temperatures. Microstructural analysis was performed to identify the intermetallic phases. It was observed that peak NA hardness strongly depends on the SHT temperature and time. SHT at 530 for 0.5 hour, slows down the peak NA hardness attaining time of the alloy to a maximum of 5 days. But as the SHT time increases to 3.5 hours, the peak NA hardness attaining time reduced to 1 day. Alloy SHT at 530 for 1 hour attain a maximum peak hardness of HRB 24 during 3 days of NA. Artificial ageing improved the hardness of the NA alloy to a maximum of HRB 41 during 12 hours of ageing at 190 . The overall hardness of Al-Mg-Si-Sn as-cast alloy increases by 32 % during ageing process.

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Liu, Hong Wei, Feng Wang, Bai Qing Xiong, Yon Gan Zhang, Zhi Hui Li et Xi Wu Li. « Ageing Precipitation and Strengthening Behavior of the Spray Formed Al-Zn-Mg-Cu Alloy ». Advanced Materials Research 535-537 (juin 2012) : 903–8. http://dx.doi.org/10.4028/www.scientific.net/amr.535-537.903.

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In this study, the Al-Zn-Mg-Cu alloy was prepared by spray forming process. The ageing precipitation and strengthening behavior of the spray formed Al-Zn-Mg-Cu alloy were studied by microhardness tests, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) .The results show that the main strengthening precipitates of the spray formed Al-Zn-Mg-Cu alloy are GPI (solute-rich clusters), GPII (vacancy-rich clusters) under peak aging condition. The effect of the microstructure on ageing hardness is controlled by the size and amount of the existing precipitates, and therefore depends critically on the ageing temperature and ageing time. Strength of this alloy is influenced significantly during natural ageing at room temperature, which is related to the dominant formation of GPI. During the initial stage of artificial ageing at 120°C, strong age-strengthening response is due to the formation of GP zones (both GPI and GPII ) .During later stages of artificial ageing , GPII precipitation is accelerated significantly but GPI is not affected clearly.

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Renaud, Alexis, Victor Pommier, Jérémy Garnier, Simon Frappart, Laure Florimond, Marion Koch, Anne-Marie Grolleau, Céline Puente-Lelièvre et Touzain Sebastien. « Aggressiveness of Different Ageing Conditions for Three Thick Marine Epoxy Systems ». Corrosion and Materials Degradation 2, n^o 4 (3 décembre 2021) : 721–42. http://dx.doi.org/10.3390/cmd2040039.

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Three different coated steel systems were aged in natural or artificial seawater, in neutral salt spray (NSS), and using alternate immersion tests in order to evaluate the aggressiveness of the different ageing conditions. Commercial epoxy coatings were applied onto steel (S355NL), hot-galvanized steel (HDG), and Zn-Al15 thermal spraying coated steel. The defect-free systems were immersed in artificial seawater at 35 °C for 1085 days and in natural seawater for 1200 days and were characterized by electrochemical impedance spectroscopy (EIS). Panels with artificial defects were immersed for 180 days in artificial seawater and, regarding adhesion, were evaluated according to ISO 16276-2. In parallel, the three coated systems were submitted to cyclic neutral salt spray (NSS) for 1440 h: defect-free panels were regularly evaluated by EIS, while the degree or corrosion was measured onto panels with artificial defect. After NSS, defect-free panels were immersed in artificial seawater at 35 °C for further EIS investigations. Finally, alternate immersion tests were performed for 860 days for the three defect-free coated systems and for 84 days for panels with a defect. The results showed that, for defect-free panels, immersions in natural or artificial seawater and NSS did not allowed us to distinguish the three different systems that show excellent anticorrosion properties. However, during the alternate immersion test, the organic coating system applied onto HDG presented blisters, showing a greater sensitivity to this test than the two other systems. For panels with a defect, NSS allowed to age the coatings more rapidly than monotone conditions, and the coating system applied onto steel presented the highest degree of corrosion. Meanwhile, the coating systems applied onto HDG and the thermal spray metallic coating showed similar behavior. During the alternate immersion test, the three coated systems with a defect showed clearly different behaviors, therefore it was possible to rank the three systems. Finally, it appeared that the alternate immersion test was the most aggressive condition. It was then proposed that a realistic thermal cycling and an artificial defect are needed when performing ageing tests of thick marine organic coating systems in order to properly rank/evaluate the different systems.

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Ma, Peipei, Lihua Zhan, Chunhui Liu, Qing Wang, He Li, Debo Liu et Zhenggen Hu. « Pre-strain-dependent natural ageing and its effect on subsequent artificial ageing of an Al-Cu-Li alloy ». Journal of Alloys and Compounds 790 (juin 2019) : 8–19. http://dx.doi.org/10.1016/j.jallcom.2019.03.072.

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Viñegra de la Torre, Natanael, Farnusch Kaschani, Markus Kaiser, Renier A. L. van der Hoorn, Wim J. J. Soppe et Johana C. Misas Villamil. « Dynamic hydrolase labelling as a marker for seed quality in Arabidopsis seeds ». Biochemical Journal 476, n^o 5 (12 mars 2019) : 843–57. http://dx.doi.org/10.1042/bcj20180911.

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Abstract Seed quality is affected by different constituents of the seed. In general, seed lots are considered to be of high quality when they exhibit fast and homogeneous germination. When seeds are stored, they undergo different degrees of damage that have detrimental effects on their quality. Therefore, accurate prediction of the seed quality and viability levels of a seed lot is of high importance in the seed-producing industry. Here, we describe the use of activity-based protein profiling of proteases to evaluate the quality of artificially and naturally aged seeds of Arabidopsis thaliana. Using this approach, we have identified two protease activities with opposite behaviours in aged seeds of Arabidopsis that correlate with the quality status of the seeds. We show that vacuolar processing enzymes (VPEs) become more active during the ageing process, in both artificial and natural ageing treatments. Secondly, we demonstrate that serine hydrolases are active at the beginning of our artificial ageing treatment, but their labelling decreases along with seed viability. We present a list of candidate hydrolases active during seed germination and propose that these protease activities can be used in combination with VPEs to develop novel markers of seed quality.

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Sinicropi, Daniela, Elena Perria, Stefano Galassi, Michele Paradiso et Antonio Borri. « Artificial Ageing of Mortar Prisms Reinforced through Steel, Glass and Organic Fibres ». Key Engineering Materials 624 (septembre 2014) : 542–50. http://dx.doi.org/10.4028/www.scientific.net/kem.624.542.

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The process of ageing in construction materials is natural and expected, and the technologies to contrast and reverse any damage due to the passing of time are well known in the field of civil engineering. This is true for structures themselves as well as the reinforcement technologies such as, for example, fiber reinforcements (FRP or FRCM). In fact, studies [1,5] have brought attention early on to severe mechanical characteristic reduction caused by the ageing process of specific resin matrices used in composite reinforcement materials, or, even more perilous, their exposure to extreme conditions of temperature. In this project, the authors have set up an experimental campaign on mortar prisms reinforced with different types of fibers and subjected to cycles of ageing through heat exposure. This paper presents the results obtained by three point flexural testing performed at the Testing Laboratory of the University of Florence, comparing the results of the reinforced and aged prisms with those of the non-aged and non reinforced prisms, providing a precedent on how ageing influences the structural behavior of fibers and mortar.

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Jakubowicz, Ignacy. « Effects of artificial and natural ageing on impact-modified poly(vinyl chloride) (PVC) ». Polymer Testing 20, n^o 5 (2001) : 545–51. http://dx.doi.org/10.1016/s0142-9418(00)00074-x.

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Porojan, Liliana, Flavia Roxana Toma, Roxana Diana Vasiliu, Florin-Ionel Topală, Sorin Daniel Porojan et Anamaria Matichescu. « Optical Properties and Color Stability of Dental PEEK Related to Artificial Ageing and Staining ». Polymers 13, n^o 23 (25 novembre 2021) : 4102. http://dx.doi.org/10.3390/polym13234102.

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Considering that the processes of PEEK discoloration caused by either intrinsic or extrinsic factors require elucidation, the aim of this study was to investigate the long-term effect of the combined action of ageing and immersing solutions on the optical properties and color stability of PEEK material, related to surface processing (polishing or glazing). (2) Methods: This study aims to determine the influence of different ageing and staining protocols on optical properties, color changes, and surface roughness of a reinforced PEEK material (bioHPP, Bredent, Senden, Germany). For ageing, specimens were submitted to 5000 cycles in a 55 °C bath and a 5 °C bath filled with distilled water. For staining, thermal cycling was performed in a hot coffee bath (55 °C) and a bath filled with distilled water (37 °C) and in a cold juice bath (5 °C) and a bath filled with distilled water (37 °C). Translucency (TP) and opalescence (OP) parameters were determined, the total color change value (ΔΕ*) was calculated, specimens’ surface roughness was analyzed, and statistical analyses were performed. (3) Results: The mean TP values of the studied samples were in the interval of 1.25–3.60, which is lower than those reported for natural teeth or other aesthetic restoration materials. The OP values of PEEK were registered in the range of 0.27–0.75, being also lower than those of natural teeth or other aesthetic restoration materials. OP has a very strong positive relationship with TP. The mean registered Ra values for all subgroups were below 0.13 µm. Artificial ageing and staining in hot coffee proved to increase the roughness values. (4) Conclusions: The glazing of PEEK has a favorable effect on surface roughness and opalescence, irrespective of the artificial ageing or staining protocols. Artificial ageing damages the color stability and roughness of PEEK, regardless of surface processing, and decreases the translucency and opalescence of glazed surfaces. Immersion in hot coffee leads to perceivable discolorations.

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Zvekic, Misha, Larissa C. Richards, Christine C. Tong et Erik T. Krogh. « Characterizing photochemical ageing processes of microplastic materials using multivariate analysis of infrared spectra ». Environmental Science : Processes & ; Impacts 24, n^o 1 (2022) : 52–61. http://dx.doi.org/10.1039/d1em00392e.

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Engler, Olaf, C. Schäfer, Henk Jan Brinkman, Calin D. Marioara, Masaya Kozuka, Hisao Shishido et Yasuhiro Aruga. « A Combined TEM and Atom Probe Approach to Analyse the Early Stages of Age Hardening in AA 6016 ». Materials Science Forum 877 (novembre 2016) : 231–36. http://dx.doi.org/10.4028/www.scientific.net/msf.877.231.

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In this study we aim at combining the results from transmission electron microscopy (TEM) and atom probe tomography (APT) to study the early stages of phase decomposition in the age hardening alloy AA 6016. Samples are subjected to different periods of natural ageing or artificial pre-ageing at elevated temperature in order to produce different types of clusters and early stages of precipitation before age hardening commences. APT is utilized to detect clusters and identify their compositions, whereas TEM is applied to analyse and quantify number density and sizes of the particles during artificial ageing at 185°C. It is shown that the two techniques, TEM and APT, are complementary and a combined approach yields more detailed insight into the early stages of phase decomposition in age hardening 6xxx series alloys than possible by the sole use of either technique individually.

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Taebenu, Freddy S. R., Heryoga Winarbawa, Rines Rines, Budi Setyahandana et I. M. W. Ekaputra. « The influence of artificial aging on tensile properties of Al 6061-T4 ». International Journal of Applied Sciences and Smart Technologies 4, n^o 1 (27 juin 2022) : 109–20. http://dx.doi.org/10.24071/ijasst.v4i1.4816.

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This paper presents an explanation related to experimental testing in the form of the tensile properties of Al 6061. Al 6061 was heat treated by the precipitation hardening method. The precipitation hardening consisted of T4 and T6 treatment. Al 6061 samples were heat-treated at a temperature of 430°C for 2 hours, then cooled slowly at room temperature. The T4 was conducted at a temperature of 530°C for 2 hours, followed by rapid cooling in a water medium and natural ageing at a temperature of 70°C for six days. Temperature T6 is the final process of applying precipitation hardening treatment to Al 6061. Temperature T6 is carried out at 530°C for 2 hours, then cooled rapidly in a water medium and continued with artificial ageing at 190°C with a variation of ageing time for 3 hours, 5 hours, and 7 hours. The effect of the applied treatment was observed to increase the maximum strength value of the tensile test of Al 6061.

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Quan, Li Wei, Rui Wu, Da Ran Fang, Yuan Yuan Liu et Chuan Cai Wang. « Effect of Pre-Treatment on the Precipitation Hardening of a Novel Al-Mg-Si Alloy ». Advanced Materials Research 881-883 (janvier 2014) : 1374–77. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1374.

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Al-Mg-Si alloy is used to investigate the bake-hardening response as automotive body panels. Natural aging followed by artificial aging at 170°C was carried on to study the effect of delaying at room temperature. Two methods are carried on to investigate the effect of pre-treatment on hardening response of Al-Mg-Si alloy. One is pre-aging in the range 80-140°Cfollowed by artificial aging at 170°C after natural aging for the same periods, and the other is retrogression treatment followed by artificial aging at 170°C after natural aging for the same periods. The properties of the alloy are tested by Vickers hardness measurements. And it is found that the optimal pre-ageing is 170°C for 30min and the opimal retrogression treatment is 230°C for 15s.

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Kubota, Masahiro. « Characterisation of Precipitate Microstructures of Natural and Artificial Ageing in Al-Mg(-Ag) Alloys ». MATERIALS TRANSACTIONS 46, n^o 2 (2005) : 241–50. http://dx.doi.org/10.2320/matertrans.46.241.

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Hachet, Guillaume, et Xavier Sauvage. « Influence of hydrogen vacancy interactions on natural and artificial ageing of an AlMgSi alloy ». Journal of Alloys and Compounds 905 (juin 2022) : 164251. http://dx.doi.org/10.1016/j.jallcom.2022.164251.

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Chen, Y., B. Q. Lu et H. A. Zhang. « Hardening and precipitation of a commercial 6061 Al alloy during natural and artificial ageing ». IOP Conference Series : Materials Science and Engineering 770 (24 mars 2020) : 012065. http://dx.doi.org/10.1088/1757-899x/770/1/012065.

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Poole, W. J., D. J. Lloyd et J. D. Embury. « The effect of natural ageing on the evolution of yield strength during artificial ageing for Al-Mg-Si-Cu alloys ». Materials Science and Engineering : A 234-236 (août 1997) : 306–9. http://dx.doi.org/10.1016/s0921-5093(97)00192-5.

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Fujda, Martin, Miloš Matvija et Miroslav Glogovský. « Effect of Natural Aging on Mechanical Response of the Artificially Aged EN AW 6063 Aluminium Alloy ». Materials Science Forum 952 (avril 2019) : 74–81. http://dx.doi.org/10.4028/www.scientific.net/msf.952.74.

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The effect of natural pre-aging time (from 0.1 to 10000 h) on mechanical response during subsequent artificial aging of EN AW 6063 aluminium alloy at 170°C was investigated using Vickers microhardness measurements, tensile test analysis and transmission electron microscopy characterization. The microhardness and tensile strength of EN AW 6063 alloy increased slightly with natural aging time. Afterward, the artificial ageing from 18 to 20 hours induced the maximum increasing of hardness and strength for variously naturally pre-aged states of alloy. But, it was found that when pre-aging time was prolonged from 0.1 h to 10000 h, the mechanical response of artificial aging applied for the pre-aged alloy states was slightly improved. It was suggested, that as pre-aging time was increased, the size of β'-phase particles formed in solid solution of pre-aged alloy state during artificial aging was decreased and their amount was increased.

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Raj, Raymon Antony, Ravi Samikannu, Abid Yahya et Modisa Mosalaosi. « Performance evaluation of natural esters and dielectric correlation assessment using artificial neural network (ANN) ». Journal of Advanced Dielectrics 10, n^o 05 (octobre 2020) : 2050025. http://dx.doi.org/10.1142/s2010135x20500253.

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The performance of correlation between the dielectric parameters of Baobab Oil (BAO) and Mongongo Oil (MGO) is evaluated using Artificial Neural Network (ANN). The BAO and MGO naturally own high Unsaturated Fatty Acids (UFAs) and are highly biodegradable. The temperature studies and dielectric studies are carried out and found that the Natural Esters (NEs) show a reliable performance over mineral oil-based Transformer Oil (TO). Further the endurance test, Partial Discharge Inception Voltage (PDIV) repetition rate and drop after 30 days, dielectric measurements are done as per the standards of IEC (International Electrotechnical Commission) and ASTM (American Society for Testing and Materials). The NEs show stable performance under PDIV and show minimum repetition rate when compared to the TO. The C[Formula: see text]H[Formula: see text] or Kerosene (KER) and NEs mixture prove that the NE-based transformer fluids show lesser tendency to hydro peroxidation. The C[Formula: see text]H[Formula: see text] acts as a thinning agent and reduces the ageing rate of the NEs, and this leads to slower rate of water saturation. This in turn increases the thermal conductivity of the oil and nearly a 30-days thermal ageing of the oil samples at 90[Formula: see text]C shows better strength of liquid insulation. The performance of association between the dielectric properties like breakdown voltage and water content, dissipation factor and thermal conductivity prove that the NEs show consistent performance and is a better substitute for the mineral oil-based TO.

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