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Pillar, Rachel Joanne, and rachel pillar@flinders edu au. "The Influence of Rolling Oil Decomposition Deposits on the Quality of 55Al-43.4Zn-1.6Si Alloy Coatings." Flinders University. School of Chemistry, Physics and Earth Sciences, 2007. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20080108.132120.
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Uncoated defects in hot dip metal-coated steel products result from non-wetting of the steel surface by the molten alloy. The occurrence of uncoated defects is highly detrimental to product quality and production efficiency; uncoated defects compromise the appearance and anti-corrosion performance of hot dip metal-coated steel products and causes time delays in the application of subsequent surface treatments. Although many studies have been directed towards evaluating the effect of steel pre-heat temperature and oxidation on the formation of uncoated defects, fewer investigations have analysed how oil-derived residues remaining on steel surface following the cold rolling and furnace cleaning processes impact upon hot dip metallic coating quality. Furthermore, although a considerable amount of research has focussed on the process of deposit formation in lubricants used in other applications, the composition of oily residues remaining after the continuous annealing process, and the origins of these residues in the original rolling oil formulation, are poorly understood.
The primary focus of the present work has been to gain an improved understanding of relationships between cold rolling oil composition, oil residue-formation characteristics and the occurrence of uncoated defects in 55Al-43.4Zn-1.6Si hot dip metallic coatings. Several key classes of rolling oil ingredients which decompose to leave high levels of thermally-stable residue have been identified. The thermal decomposition processes undergone by a variety ingredients within these classes have been studied under both oxidising and reducing conditions using Thermogravimetric Analysis (TGA) and Pressure Differential Scanning Calorimetry (PDSC) techniques, with chemical characterisation of the decomposition process and the resultant thermally-stable residue by infrared spectroscopy. Model blends of each ingredient in a typical cold rolling oil base ester have also been evaluated by TGA and PDSC to identify the impact of ingredient concentration and chemical structure on the amount of oily residue formed. The results of these investigations have been related to the impact of the ingredients on 55Al-43.4Zn-1.6Si hot dip metallic coating quality through the performance of industrial-scale hot dipping trials and hot dip simulation studies.
In order to translate these results into a context more closely aligned with industrial conditions, the effect of processing variables, including furnace atmosphere and the availability/concentration of iron in contact with the rolling oil at the steel surface, on the decomposition process of a fully-formulated commercial cold rolling oil has also been investigated. The information gained can potentially be used to tailor operating conditions within the cold rolling/continuous hot dip metallic coating processes to enhance steel surface cleanliness.
Finally, the deposit-forming tendencies of an array of different commercial cold rolling oils have been evaluated, leading to the development of a thermal analysis-based test for screening cold rolling oils with respect to their likely impact upon 55Al-43.4Zn-1.6Si hot dip metallic coating quality. This test, together with the understanding obtained on the effect of different rolling oil ingredients on hot dip metallic coating quality, can be used within the industry to formulate improved cold rolling oils.
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Lodwig, Geraint Wyn. "Hot dip coating of high strength low carbon steels." Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa42742.
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In response to increasing demand for high strength automotive steels, the development of galvanised dual phase steels has become more significant in recent years. At present, a requirement for galvanised high strength steels with tensile strengths in excess of 600 MPa exists within the automotive industry. The present programme focuses on seven C-Mn based steels, each steel varying in key additions such as silicon, chromium, vanadium, molybdenum and niobium. A composition range wt% of C (0.07-0.2), Mn (1.3-1.5), Si (0.05-1.3), Cr (0.05-0.45), V (up to 0.01), Mo (up to 0.01) and Nb (0.001-0.01) was studied. In order to attain these wide-ranging steel chemistries, both commercially produced and laboratory cast steels were used for this project. All steels had the required chemistry for dual phase steel production, but only if a suitable annealing cycle was used. As a result, all steels were subjected to a range of annealing cycles on a laboratory-annealing simulator, based on current continuous annealing/galvanising line schedules utilised by the Corus Group. Steels identified as dual phase steels from annealing experiments by microstructural and mechanical property analysis were subjected to laboratory galvanising. The zinc coating applied to these steels has been studied to evaluate the quality of the galvanised steel. This investigation, which has utilised a galvanising simulator, has demonstrated that during standard galvanising practices, problems known as dewetting affected the coating quality. Unfortunately, this issue was most prevalent with the steels displaying the most suitable metallurgical properties. Nevertheless, the wetting performance could be vastly improved by varying processing conditions such as annealing furnace dew point and strip entry temperature.
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Burris, Matthew L. "Material evaluation of liquid metal corrosion in Zn-Al hot-dip coating baths." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1400.
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Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 71-73).
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SURYANARAYANAN, KARTHIK. "INTEGRAL EPOXY RESIN-SILANE PRIMER SYSTEM FOR HOT-DIP GALVANIZED STEEL." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1130950464.
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Staudte, Jonas [Verfasser]. "Surface Conditioning of High-Strength Steels for Improved Hot-Dip Coating Behaviour / Jonas Staudte." Aachen : Shaker, 2003. http://d-nb.info/1179022173/34.
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Price, M. "Strip position measurement and control for consistency of zinc coating in hot-dip galvanising lines." Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638578.
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The stability of the strip between the gas knives during the wiping stage of hot-dip galvanising is critical for consistent zinc coating mass. Variation in this coating mass can result in a product that does not meet customer requirements. A significant saving can be made on the amount of zinc used and the quality of the product will be enhanced if the tolerances on the coating mass are tightened. A dynamic distributed parameter model is developed for understanding strip vibration and design of a controller for stabilisation, and is implemented in the simulation package SIMULINK. The model can be stimulated at any point by a force input and the displacement and velocity of any point can be measured. A physical model has been developed, for the purposes of validation and for test purposes, and is a scale representation of the critical part of the hot-dipping process. The computer model and physical models can be matched by use of appropriate stimulation signals and the use of genetic algorithms. The matched models show a good correlation and the confidence in the model is high. Currently air cushions and touch rolls are used to stabilise strip and the effect of these systems on the strip can be shown using both the computer and physical models. The computer model is used to develop a control scheme using the techniques of root-locus and Nichols charts. The response of the controlled system is analysed using Bode plots and step responses and shown to be an improvement on the uncontrolled system. The actuator, sensor and electronics for physical realisation of the designed control scheme are also given. The work presented here shows the method of producing a control scheme for improving the stability of strip steel within hot-dip galvanising lines.
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Marsland, Wayne Edmund. "Positive release of hot-dip galvanised automotive material to prevent coating adhesion failure at customer." Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678444.
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Williams, Joseph James. "Surface reactions of zinc vapour with steel relevant to the Zn-55%Al-1.5%Si hot dip metal coating process." Faculty of Engineering, 2005. http://ro.uow.edu.au/theses/395.
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Zn-55%Al-1.5%Si coated steel strip is manufactured by the continuous hot dipping process. An important difference in the processing of Zn-55%Al-1.5%Si coated steel when compared with galvanised steel is the higher temperature of the molten alloy bath –600ºC for Zn-55%Al-1.5%Si coatings versus 450ºC for galvanised. This increase in temperature leads to an accelerated rate of evaporation of zinc into the pretreatment furnace, leading in turn to various processing difficulties. Zinc vapour in the pre-treatment furnace has long been implicated with defects known within the industry as pinholes and bare patches - uncoated areas where wetting does not occur between the strip and the molten alloy. Despite the association with zinc vapour, the exact mechanisms of pinhole and bare patch formation have not been clearly established. One possible mechanism of pinhole and bare patch formation is the direct reaction of zinc vapour with the strip surface. It has been suggested by industry experts that zinc vapour could condense on the strip, leaving a deposit that prevents wetting by molten Zn-55%Al-1.5%Si alloy. It remains that little is understood of the fundamental nature of the interaction between zinc vapour and a steel substrate. The purpose of this research was to examine the rates and mechanisms of zinc vapour condensation on clean and oxidised steel substrates. Such information is essential for understanding the reactions that occur in the metal coating line furnace. It is intended that this research will strengthen the fundamental knowledge base upon which a solution to the problem can be developed. The experimental work conducted in this study was centred on condensing zinc vapour onto substrates under specific gaseous atmospheres at atmospheric pressure. A major part of the work involved the development of a technique for depositing zinc vapour onto a steel substrate and the design and construction of an experimental apparatus. Preliminary studies were undertaken to define the design criteria for an apparatus in which the rate of condensation of zinc vapour could be measured accurately and the interaction between zinc vapour and clean and oxidised steel substrates could be examined. In this probing exercise, modifications were made to a proven design of an apparatus designed to measure evaporation rates of metals in inert gas atmospheres was used. The preliminary experiments provided a wealth of essential knowledge required to design an experimental facility in which it was possible to accurately measure the rate of condensation of zinc vapour and to study the interaction between zinc vapour and the steel substrate, as well as their potential chemical reactions. This new apparatus was specifically developed for a quantitative assessment of zinc vapour deposition, and allowed the substrate and zinc vapour to be heated in independent, but interconnecting chambers. The exposure of the substrate to the zinc vapour could be controlled with precision, and it was possible to not only measure the zinc vapour condensation rates, but also to assess the effect of using oxidising and reducing gasses during preheating of the substrate. Under conditions of high undercooling, zinc vapour deposited by the island plus continuous thin film mode, while at higher substrate temperatures, close to that expected in the industrial process, the zinc deposited more slowly, and zinc islands did not form on the substrate within the first 60 seconds of exposure. Deposition of zinc vapour on an oxidised substrate occurred at a much higher rate than on a clean steel substrate. This increase in deposition rate has been attributed to a direct reaction occurring between the zinc vapour and the iron oxide without the formation of any liquid condensate. The reaction is: Fe3O4(s) + 4Zn(v) ↔ 4ZnO(s) + 3Fe(s) This reaction will proceed to the right under sufficiently high partial pressures of zinc vapour, and at substrate temperatures both above and below the saturation temperature of the zinc vapour. It was observed that under sufficiently low partial pressures of zinc vapour, the above reaction is driven to the left. Zinc oxide has a determining influence on the wetting of the strip by the molten alloy. Immersion tests, wherein substrates deposited with zinc vapour were dipped into molten Zn-55%Al-1.5%Si alloy, were carried out to examine the effect of various zinc vapour reactions on the quality of the coatings. Deposition of zinc vapour on both clean and oxidised steel surfaces had a detrimental effect on the coating quality. In cases where zinc was deposited onto a clean steel substrate prior to immersion in the coating alloy, pinholes resulted, while zinc vapour deposition on an oxidised surface prior to immersion led to large scale uncoated areas.
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Brunnock, M. S. "Development of materials with improved resistance to molten metal attack in hot-dip zinc coating lines for strip steel products." Thesis, Swansea University, 1998. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636166.
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A study has been carried out of the resistance to molten zinc of a series of candidate materials. The object was to identify those that might be capable of increasing the service life of hot-dip galvanising bath hardware rolls. The testing involved immersing samples in a molten zinc alloy, representative of that used in commercial operations, at 455° and 480°C for periods up to 360 hours. For some programmes of tests the samples were rotated during immersion. The candidate materials ranged from uncoated low carbon steel, commercial and experimental stainless steels and cobalt-base superalloys to some of the same products covered with a variety of non-metallic and ceramic coatings. Although an Fe-18%Cr experimental alloy had poorer resistance to liquid zinc than low carbon steel, the further addition of 9%Ni to produce an experimental Type 304 stainless steel generated better liquid zinc resistance than low carbon steel. It is suggested that structure rather than compositional effects play an important part in this. Microstructures containing significant amounts of martensite appear to be particularly susceptible to zinc attack. There is, however, a compositional effect from silicon which, when varied in experimental cases of a Type 316 stainless steel, showed the same ability to influence coating microstructure as in carbon steels. The effectiveness of coatings was related to two factors: their inertness and their integrity. Some coatings, for example nitrided and titanium nitrided steel, appeared to be attacked by liquid zinc. Tungsten carbide/cobalt were also attacked unless an inert sealant had been applied. Ceramic oxide coatings consisting of a mixture of fine particles of alumina, chromia and silica proved highly effective in countering zinc attack. However discontinuities in inert coatings arising from the manufacturing process or from microsfissuring during periods of sharp temperature change promoted opportunities for zinc attack and undercutting of the coating. An unexpected phenomenon was observed on some semi-immersed samples. Liquid zinc attack occurred progressively above the liquid zinc meniscus to the formation of thick intermetallic layers. In some cases these layers engulfed the sample and sample holder. The phenomenon has been termed 'supermeniscus intermetallic climb' (SMIC).
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Aldén, Rickard. "Metallurgical investigation in weldability of Aluminium Silicon coated boron steel with different coating thickness." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171209.
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Hot-pressed aluminium and silicon coated boron steel is used in the car industry where high tensile strength is of great importance, such as in the safety cage of a car where deformation has to be kept to a minimum in case of a collision. After hot-pressing the AlSi-boron steel shows excellent properties with high tensile strength, minimal spring back and also shows good protection against corrosion. A thickness of the AlSi coating of 150 [g/m2] for AlSi coated boron steel is typically used by the car industry today. However the coating thickness would be desirable to be minimized to 80 [g/m2]. Welding of this boron steel with 80 [g/m2]have shown difficulties; and it’s not clear why this occurs. In this report the metallurgical properties of the different coating layers will be investigated, simulations with Thermocalc module Dictra will be used, SEM/EDS will be used to characterize phases in coating layers and correlate to weldability. Resistance spot welding tests will also be performed where the welding parameters of pre-pulse, pulse time, time in between pulses and current will be varied to achieve desirable weld plug diameter without expulsion. Hardness testing in form of micro Vickers will executed. The Materials used will be USIBOR® 1500, AS80 with four different annealing times and one sample of AS150.
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Lima, Graziela de. "influência da adição de diferentes concentrações de bismuto, níquel, estanho e alumínio sobre a espessura de camada, resistência à corrosão e brilho nos revestimentos galvanizados." Universidade do Estado de Santa Catarina, 2007. http://tede.udesc.br/handle/handle/1716.
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Blackeart malleable iron samples were galvanized using twenty different zinc bath compositions. Each bath was made with different concentration and combinations of bismuth, nickel, tin and aluminium. These additions aim not only to substitute lead, a hazardous element to the environment, but also to reduce coating thickness, usually higher than established by standards due to the great reactivity between cast iron and zinc bath. Additional studies were made to check the corrosion resistance and to check the maintenance or intensity of the coating s brightness. When using just bismuth and nickel additions to the zinc bath, it wasn t observed a considerable coating thickness reduction, but bismuth influenced bath fluidity, favoring better zinc draining and formation of more compacted and defined zinc-iron compounds. It was observed that bismuth decreased the coating s corrosion resistance, while nickel can increase the corrosion resistance when the bath has small bismuth concentrations. Tin addictions reduced the coating thickness when used together with bismuth and nickel addictions. However, tin did not only reduce the corrosion resistance, but also decreased the coating s brightness. Highest aluminium concentrations reduced the coating s thickness considerably when compared to the coating s thickness of the samples galvanized in the other baths. Aluminium also increased corrosion resistance when compared to the coatings of the samples galvanized in baths containing bismuth, nickel and tin. However excessive coating thickness reduction, caused by highest aluminium addictions to the bath, reduced corrosion resistance. Highest aluminium addictions were totally favorable to the coating s brightness. The combination of bismuth, nickel, tin and aluminium were effective on coating thickness reduction and some of these combinations also provided greater rust resistance and shinier coatings. Hence, the chemical elements added weren t detrimental to the environment and they are good alternatives to substitute lead in the hot-dip galvanizing process.
Amostras de ferro fundido maleável preto foram galvanizadas em vinte diferentes banhos de zinco, cada qual composto por concentrações e combinações variadas de bismuto, níquel, estanho e alumínio. Além de substituir o chumbo, um elemento tóxico e nocivo ao meio ambiente, objetiva-se com estas adições a redução da espessura do revestimento galvanizado, normalmente em excesso ao estabelecido em norma devido à grande reatividade dos ferros fundidos com o banho de zinco. Estudos adicionais foram realizados para a verificação da resistência à corrosão e para a verificação da manutenção ou intensificação do brilho dos revestimentos. Utilizando adições somente de bismuto e níquel ao banho de zinco não foi observada uma redução considerável da espessura do revestimento, mas o bismuto influenciou na fluidez do banho favorecendo o melhor escorrimento do zinco e a formação de fases zinco-ferro mais compactas e definidas. Observou-se que o bismuto diminuiu a resistência à corrosão dos revestimentos, mas o níquel pode aumentar a resistência à corrosão quando se têm adições menores de bismuto ao banho. Adições de estanho reduziram a espessura de camada quando utilizadas em conjunto com adições de bismuto e níquel, mas o estanho foi prejudicial à resistência à corrosão além de diminuir o brilho dos revestimentos. O alumínio em concentrações mais elevadas tornou as espessuras dos revestimentos consideravelmente menores quando comparadas às espessuras dos revestimentos galvanizados nos outros banhos estudados. O alumínio ainda aumentou a resistência à corrosão dos revestimentos em relação aos revestimentos galvanizados nos banhos contendo bismuto, níquel e estanho. Contudo a redução excessiva da espessura da camada, proporcionada por adições maiores de alumínio, fez com que a resistência à corrosão diminuísse novamente. Adições de maiores teores de alumínio foram totalmente favoráveis ao aumento do brilho dos revestimentos. A combinação de elementos químicos como o bismuto, níquel, estanho e alumínio mostrou-se efetiva na redução da espessura de camada, sendo que algumas destas combinações também proporcionaram maiores valores de resistência à corrosão e revestimentos com brilhos mais intensos. Além disso, os elementos químicos adicionados não são nocivos ao meio ambiente, sendo boas alternativas para substituir o chumbo na galvanização por imersão a quente. Palavras-chave: galvanização por imersão a quente, espessura de camada, resistência à corrosão, compostos intermetálicos zinco-ferro.
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Wang, Gaung-Hao, and 王光浩. "Ceramic Coating Obtained by Micro-Arc Oxidation of Hot-Dip Aluminized Coating on Steel." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/01690463393572945272.
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碩士龍華科技大學
工程技術研究所
101
This study aims at coating ceramic membrane on the surfaces of carbon steel and stainless steel in order to achieve the objective of surface modification. Two specimens, after being hot-dip aluminized, further went through the process of micro-arc oxidation and generated ceramic membranein order to explore whether the properties of these two materials have been enhanced after surface modification. The study was divided into twophases. The first stage was to fabricate aluminum coating with sufficient thickness in order to facilitate the second stage of micro-arc oxidation treatment, while the second stage was to conduct micro-arc oxidation on the hot-dip aluminum specimens in order to form ceramic membrane on their surfaces so as to explore whether or not the properties of ceramic membranes are superior to those of carbon steel and of stainless steel substrates. Research findings of the first phase showed that 9.03μm aluminum coating can be prepared for carbon steel substrate under the condition of 700℃ aluminum soup at 6cm/min moving out speed and 3 minutes of dipping time, whereas the coating thickness of stainless steel can reach 36.69μm at the same condition. The results of the second phase indicated that the thickness, corrosion resistance, roughness and hardness of ceramic membrane were increased with the rise of micro-arc oxidation operating voltage, whereas the corrosion resistance of carbon steel with ceramic membranes had elevated to 5-17 times higher than that of its original substrate, while the corrosion resistance of stainless steel increased about 1-4 times higher than its original substrate.
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Rong, Woei, and 陳偉榕. "Cracking Behavior of Zinc Coating on Hot-Dip Galvanized Steel sheets." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/53060524406866157420.
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碩士義守大學
材料科學與工程學系碩士班
94
The effects of zinc coating thicknesses, steel sheet substrates, baking treatment and prepainting process on the crack resistance capability of hot-dip galvanized steel sheets in deformation were studied. The relationship between zinc cracking modes and the deformation mechanisms of the zinc coatins were also discussed. These zinc coatings obtained from a continuous hot-dip galvanizing line consisted of δ, ζ and η-Zn phase. The hot-dip galvanized coatings showed a strong preferred orientation on the basal plane. 180∘0T bending deformation tests and tensile deformation tests were performed on the galvanized steel sheet samples to understand the deformation mechanisms and cracking behaviors. Microstructural observations indicated that the thicker zinc coatings exhibited worse cracking resistance in the 180∘0T bending deformation tests. Zinc coatings on annealed steel substrates showed better crack resistance than those on full hard steel substrates. Grain boundary separation and transgranular cleavage were responsible for the dominated cracking modes in the uniaxial tensile deformation and 180∘0T bending deformation, respectively. Mechanical twinning plays an important role in the deformation of zinc coatings. Peelings at the interface between the steel substrate and zinc coating were also observed at the rupture point after tensile tests. 300℃ baking treatment and commercial prepainting process showed helpful to improve the crack resistance capability of hot-dip zinc coatings. Recrystallization of zinc layer was found to be the root cause of the crack resistance improvement after prepainting or baking treatment.
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Sun, C. N., and 孫震南. "Research on Color Anodizing of the Hot-Dip 5%Al-Zn Coating." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/88058027072625478673.
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Chiu, Po-Han, and 邱柏翰. "Study on preparation of MAO ceramic coating on CP-Ti hot-dip aluminum." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/s45abb.
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碩士大同大學
材料工程學系(所)
102
The Al2O3 layer on the CP-Ti hot dip aluminum (HDA) can be successfully produced by microarc oxidation (MAO) treatment. The thickness of Al2O3 layer increases with increasing MAO time. However, the growth rate of Al2O3 layer will reach a maximum value around 20 minutes of MAO. The MAO sample prepared for 20 minutes exhibits the best corrosion resistance in 3.5 wt.% NaCl solution. The larger pore size on the surface of the sample prepared for more than 20 minutes can account for the poorer corrosion resistance. The thickness and hardness of Al2O3 layer is critical to the abrasion resistance. The wear resistance of the coatings can be improved significantly with the increase of MAO time, i.e. the thickness of MAO coatings. In this work, the sample prepared for 40 minutes of MAO perform best wear resistance.
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Huang, Bing-Yi, and 黃秉毅. "High-temperature Fatigue of Hot-dip Aluminide Coating on Mild Steel and Weldments." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/3jf2bv.
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碩士國立臺灣科技大學
機械工程系
104
This study performed a creep and fatigue test on mild steel, hot-dip aluminide coating on mild steel, and weldments at high temperatures of 540 °C and 288 °C. The specimens were given two-axial stresses: a longitudinal tensile stress and a lateral repeated fatigue stress. The fatigue behavior of mild steel and hot-dip aluminide mild steel at high temperatures was discussed. The results show that the mild steel fractured under 147 MPa at 540 °C after reaching 104 fatigue cycles, whereas the hot-dip aluminide mild steel fractured after completing 106 fatigue cycles. The tongue-like Fe-Al intermetallic layer of the alumnide steel can effectively resist the axial tensile stress, preventing the substrate from necking and thereby significantly lengthening the creeping process and prolonging the limit life. The mild steel weldments fractured under the tensile stress and repeated fatigue stress of 220 MPa at 288 °C upon reaching 105 fatigue cycles. The mechanical properties of mild steel, such as tensile strength and high-temperature fatigue resistance, are better at 288 °C than at 540 °C.
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Hou, Wen Xuan, and 侯文炫. "Fracture strength and microstructure of zn-based coating on hot dip galvanizing steel sheet." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/34993051019951206371.
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SHUN, LI HSHAH, and 黎玄順. "Galling effect of tool coating materials to the hot-dip galvanized steel sheets upon pressing." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/58142934887408309413.
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碩士中華大學
機械與航太工程研究所
89
SKD11-steel and SS41-steel are used as the substrates of die materials which were coated with TiN , CrN and DLC materials. The hot dip galvanized steel sheet was applied to evaluate the galling effect during press processes. According to the results of the surface roughness measurements and the hardness of the coating , surface roughness and hardness of die with coating materials are superior to which without coating materials. On the other hand, in terms of formability and coefficient of friction, die with coating materials also performs better than that without coating materials. Moreover, it was found that DLC coated materials have the best performance of formability, coefficient of friction and galling comparing with CrN and TiN materials. In addition, if considering SS41-steel and SKD11-steel plated with DLC material, SS41-steel is more competitive than SKD11-steel when expense is taken into account.
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Huang, Che-Fong, and 黃澤峰. "Effects of Crystalline Structure of Zine Coating on Hot-Dip Steel to the Corrosion Resistance." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/49b333.
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碩士國立臺北科技大學
製造科技研究所
96
This research is discussion that the hot dip galvanizing steel plate corrosion the state under different zinc crystallization, in the hope of finding out about the crystallization type influence on the anticorrosive ability of the hot dip galvanizing steel plate. Make use of heat produced by different manufacturers to soak its inside of experimental analysis of hot dip galvanizing steel plate and make up composition and structure, contrast and compare the difference that the two corrosion the state further, find out the crystallization type attitude and dependence of corrosion the speed . Set up carbon steel , stainless steel , zinc-plated steel of CIN , KGB zinc-plated four groups of different kinds of hot dip galvanizing steel plate first in experiment , observe its change after the salt fog is tested according to different time. The result of study can find that the carbon steel corrosion the speed biggest while comparing the change that four groups corrosion the speed , later it was zinc-plated steel of KGB , zinc-plated steel of CIN , stainless steel in order. Is it find CIN zinc-plated zinc crystallization type attitude of steel after comparing to analysis to hot dip galvanizing、steel plate with(2 1)The crystallization of the direction is a main fact, the zinc crystallization type attitude of the zinc-plated steel of KGB is as the main fact with the crystallization of the direction, find through the software simulation of solid works that KGB crystallization direction is closer than CIN crystallization direction is arranged , but the experimental result of salt fog is the anticorrosive ability of CIN crystallization direction relatively KGB crystallization direction is good, observe the galvanized layer surface and find one layer of surface of CIN zinc is made up brilliantly by more careful the cube further, one layer of surface of KGB zinc forms brilliantly for the slice, because the cube is exposed to the air surface brilliantly brilliant and smaller than the slice and the air is relatively slow in response, so the zinc-plated steel of CIN resists the ability of losing and is superior to the zinc-plated steel of KGB. After research we can know that different zinc crystallization directions cause different plating one layer of superficial attitudes and opposing and having its apparent influence to corrosion ability by the result of this study.
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Su, Ken Yu Jen. "Effect of Laser Welding and Stretch Forming on the Corrosion Performance of Hot-Dip Galvanized Steel." Thesis, 2008. http://hdl.handle.net/10012/4088.
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The use of laser welding in the automotive industry in the past few decades has facilitated joining of hot-dip galvanized (HDG) steel sheets at high production rates and low cost. The recent development of tailor welded blanks (TWB) using laser welding allowed combinations of sheet grades and thicknesses to “tailor” the vehicle part for optimized design, structural integrity and crash performance but more importantly, reductions in weight. Welded blanks are further subjected to stamping or stretch forming prior to final assembly. Unfortunately, both welding and stretch forming cause the galvanized coating to deteriorate, and thereby, undermine the long term corrosion protection. Despite existing publications on zinc coated steel and advances in processing techniques, there is a lack of understanding on the influence of laser welding and stretch forming on the corrosion performance of HDG steel. Hence, the purpose of this study was to determine how welding speed and biaxial strain affect interstitial-free (IF) and high strength low allow (HSLA) steel coupons when they are subjected to continuous immersion and accelerated corrosion tests. The corrosion rates of the coupons were evaluated using electrochemical techniques and gravimetry.
Changes in the galvanized coating were characterized using scanning electron metallography. It was observed that, the original zinc layer transformed into the delta and gamma Fe-Zn intermetallic phases locally in the heat affected zone (HAZ) after laser welding. The resulting microstructure was similar to that of a commercially galvannealed coating and exhibited superior corrosion resistance than that of pure zinc.
Linear polarization resistance (LPR) measurements revealed that the zinc coating was able to protect a chemically exposed region of steel in 0.1 M NaCl solution. While the Nd:YAG laser welded coupons with narrow HAZs performed equally well as the non-welded ones, diode laser welded coupons, with a wide locally annealed coating in the HAZ, exhibited a decrease in the peak corrosion rate of zinc. Moreover, minimal amounts of rust were observed on the surface of the HAZ after testing. With biaxial strain, welded and deformed coupons generally demonstrated higher peak corrosion rates than that of undeformed welded ones.
When subjected to cyclic corrosion testing according to SAE J2334, rust formed in the exposed region after one 24 hour test cycle due to wet-dry conditions. However, zinc corrosion products on the surface provided substantial corrosion resistance to the remaining zinc coating and to the steel substrate. Gravimetric measurements of welded coupons showed a linear increase in weight gain with increased exposed widths of the steel after 30 cycles but biaxial strain further increased the weight gain on deformed coupons. After 60 cycles, the trend became exponential for both welded and deformed coupons. There was a negligible difference between the corrosion performance of IF and HSLA steel.
Using X-Ray diffraction and Raman spectroscopy, species of both iron and zinc corrosion products were identified. Without the application of paint coatings, zinc oxide (ZnO), zinc hydroxy chloride (ZnCl2[Zn(OH)2]4), and hydrozincite ([ZnCO3]2[Zn(OH)2]3) were responsible for passivating the surface and reducing the overall corrosion rate of the galvanized coating.
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Su, Jia-Ying, and 蘇家瑩. "The Discussion and Comparison of Zinc Cracking between Hot-Dip Galvanized Steel Sheets and Zn-5wt%Al Coating Steel Sheets." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/36206839505534470239.
Full textAbstract:
碩士義守大學
材料科學與工程學系碩士班
96
In this research we made a comparison between the zinc cracking behavior of hot-dip 5% aluminium zinc steel sheets (Galfan Steel Sheets, GF) and that of hot-dip galvanized steel sheets (Galvanized Steel Sheets, GI), and discussed the baking treatment effect on the crack resistance. The specimens were acquired from a continuous hot-dip galvanized line. We analyzed the cracking resistance of coatings by using bending deformation tests and tensile deformation tests. We also performed the baking treatment to simulate the prepainting process. The thermal effect of prepainting process on the cracking resistance of coatings was discussed. The microstructure changes, and the cracking models after 180° 0T bending deformation and tensile test were studied using OM, SEM, EDS, GDS and XRD. The results showed that GI was superior in cracking resistance to GF. XRD analysis results showed that preferred orientation of GI changed from plane (002) to plane (100) or plane (101) during tensile deformation. During deformation process, a large amount of mechanical twins was generated in the hexagonal-closed-packed zinc solid phase in GI coating. Even though mechanical twinning occurs in GI was helpful to relax partial deformation strain and contribute more slip systems in the tensile deformation. However, mechanical twinning in GI changed the preferred orientation significantly and made the transgranular cleavage developing easier alone the basal plane of zinc. In contrast with GI, the eutectic structure of GF coating suppressed the occurrence of mechanical twinning suppressed. The cracking of GF prefered the mode of grain boundary separation after tensile test. The cracking of thicker coating prefers the mode of transgranular cleavage after bending test, Both grain boundary separation and transgranular cleavage could be observed in thinner coating after bending test. The experimental results also indicate that the coatings on the annealed steel substrate were superior in cracking resistance to the coatings on the full hard steel substrate. Zinc cracking resistance was found to decay after cyclic baking treatment. The porosity generation inside the Zn layers during cyclic baking treatment, which could be explained on the basis of the Kirkendall effect, was believed detrimental to the cracking resistance of Zn coatings.
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沈哲儀. "The effect of tool coating materials and solid lubricants on the formability of the hot-dip galvanized steel sheets upon pressing." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/24510540900725630846.
Full textAbstract:
碩士中華大學
機械與航太工程研究所
90
In this study，SKD11 and SS41 are used as the substrates of die materials which were coated with TiN , CrN and DLC materials. The hot-dip galvanized steel sheet that were sprayed with 6917、6917 with graphite 、AC200、AC200 with graphite、AC240、AC240 with graphite、PU、PU with graphite、SS150、SS150 with graphite and Teflon（PTFE） was applied to evaluate the formability during press processes. According to the results，the formability of hot-dip galvanized steel using the die with coating materials is better than that using die without coating materials . Specimens Added of solid lubricants were found also improving the formability of the specimens. It was found that PU and PU with graphite are the two solid lubricants that can improve the formability of materials with or without using die coating materials. However， the use of these two lubricants will increase the coefficient of friction. The SKD11 die material with the use of solid lubricant AC200 had been measured with the least of coefficient of friction，but its improvement of formability is insignificant. According to the results ，the use of solid lubricant SS150 with all die materials is the best choice not only for improving formability but also achieving good coefficient of friction.
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Lin, Chiung-Sung, and 林敻崧. "The Effects of Annealing Heat Treatments on The Coating Layer Formed on The Hot Dip Aluminum Coated Fe-Al-Mn-C Alloys." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/72771041388356691075.
Full textAbstract:
碩士國立交通大學
材料科學與工程系
91
The effects of annealing treatments at 700℃ and 800℃ on the internetallic phases formed in the coating layer of the hot dip aluminized Fe-Al-Mn-C alloys have been investigated. Scanning transmission electron microscopy observations revealed that after hot dip aluminum coated Fe-Al-Mn-C alloys, the average grain size of the intermetallic phase was 200~220 nm, and then grew to about 600~800 nm and 1200~1600 nm after annealing treatments at 700℃ and 800℃ for 30 minutes. Experimental results showed that the growth of the intermetallic layers was dominated by diffusion-controlled kinetics during annealing treatment. After annealing treatment at 700℃ for 30 minutes, the intermetallic phase formed in the coating layer of the hot dip aluminized Fe-Al-Mn-C alloys was the single intermetallic phase (Fe,Mn)2Al5 with orthorhombic structure. In contrast to this observation, the A12 α-Mn would precipitate at the grain boundary of the intermetallic phase (Fe,Mn)2Al5 after annealing treatments at 800℃ for 30 minutes. EDS analyses indicated that the A12 α-Mn only contain about 24.4at.% manganese. Compared to Al-Mn, Fe-Mn, Fe-Al-Mn and Fe-Al-Mn-Cr alloys, it was found that the A12 α-Mn observed in the present alloy consisted of lower manganese and had a higher existing temperature. In addition, the lattice constant of the intermetallic phase (Fe,Mn)2Al5 from outer layer to inner layer would decrease with composition change caused by the diffusion process. Also, microhardness test revealed that the hardness of the intermetallic layer obviously decreased after annealing treatments at 700℃ and 800℃.
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YU, CHIA-CHUN, and 余家俊. "The Planning and Experimental Validation of the Process Parameters for Optimizing the Coating Amount of Continuous Hot-dip Zinc-plated Steel Using the Taguchi Methods." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/20121334872011655463.
Full textAbstract:
碩士國立高雄應用科技大學
機械與精密工程研究所
104
This research aims to study the process parameters for optimizing the coating amount of continuous hot-dip zinc-plated steel utilizing the “smaller-the-better” characteristic of the Taguchi methods. The four process parameters, including the linear velocity, temperature of the annealing plate, wind pressure of the air knife blower, and temperature of the zinc tank, were used as the control factors of the zinc coating amount; and the values of three levels were set. The L9(34) orthogonal table was used to plan the process parameters. The average values, standard deviations, and the S/N ratios were calculated; and the analysis of variance (ANOVA) was conducted to obtain the combination of the optimized process parameters, the S/N ratio, and the prediction of the optimized zinc coating amount. The widths of the steel plates discussed in this study are between 3 to 4 feet, and the air knife controlling the zinc coating amount is a bilateral air-intake air knife with a blade length of 1580 mm. This research focuses on the processes of the 55% aluminum-zinc coating and the 95% zinc coating. Five sets of steel plates with different length-thickness ratios were used for each process. The average values of the coating amount (g/m2) were measured using the two-side-three-point method, and the analysis of the optimized parameters was then conducted utilizing the “smaller-the-better” characteristic of the Taguchi methods. Through the ANOVA analysis, we realized that the linear velocity made a larger percentage of contribution among the parameters. Lastly, experiments were conducted using the optimized parameters of one set of steel plates from each process, and measurements were taken. Through comparisons, it was confirmed that the optimized process parameters can indeed effectively reduce the average zinc coating amount of hot-dip zinc-plated steel, making it approach the required minimum coating amount, which can save the material costs of the aluminum and zinc ingots.
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Chuang, Che-Hao, and 莊哲豪. "The Study on Corrosion Behaviors of Hot-Dip Aluminized Coating Formed on Low Carbon Steel by Anodic Treatment in the Sodium Chloride Aqueous Solution and High-Temperature Oxidation." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53667859144585051307.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
97
AISI 1005 steel was coated by hot-dipping into a molten pure aluminum, and then underwent an anodizing treatment to form an anodic oxide layer on the coating surface. The corrosion behavior of the modified aluminide steel was analyzed by immersion and electrochemical tests in NaCl aqueous solution and high-temperature oxidation and hot corrosion tests. The results showed that the anodized aluminide steel can not used in high-temperature oxidation and hot corrosion environment due to the spallation of the anodic alumina oxide layer caused by the thermal stress. On the other hand, the immersion and electrochemical tests in NaCl aqueous solution revealed that corrosion resistance of the aluminide steel after anodizing treatment of 60 minutes is better than the mild steel and aluminide steel, indicating that the aluminide mild steel after anodizing treatment can enhance its corrosion resistance in NaCl aqueous solution.