Academic literature on the topic 'Cold-extruded mild steel rods'

Abstrak: Pertumbuhan atau kenaikan penduduk Indonesia yang sangat pesat mengakibatkan bertambahnya jumlah kebutuhan rumah tinggal yang juga semakin meningkat. Saat ini pembangunan seperti apartemen, dan perumahan sangat banyak didaerah perkotaan yang diakibatkan karena bertambahnya penduduk, atau migrasi dari desa ke perkotaan untuk mengimbangi dari pertumbuhan penduduknya. Rumah - rumah yang dibangun di perumahan pada umumnya banyak yang menggunakan rangka baja ringan sebagai atapnya. Material rangka atap biasanya dari kayu, beton, baja dan baja ringan, masing-masing memilik kelebihan dan kekurangannya. Dalam hal ini material kuda-kuda baja ringan mempunyai banyak kelebihan dibandingkan dengan material yang lainnya dalam penelitian-penelitian yang dilakukan sebelumya. Beberapa tipe rangka untuk baja canai dingin antara lain tipe Howe, Pratt, Fan, Fink, Scissors dll. Untuk itu perlu dilakukan optimasi dari bentuk-bentuk rangka kuda-kuda baja ringan, untuk mencari bentuk rangka yang optimum, aman, ekonomis dan efisien. Penelitian ini bertujuan untuk mendapatkan bentuk optimum maksimal dari rangka kuda-kuda baja ringan, megetahui beban maksimal, lendutan maksimal pada konfigurasi rangka, angka keamanan dan pola keruntuhan dari rangka kuda-kuda baja ringan akibat beban statis, sehingga bisa dijadikan sebagai rujukan untuk diterapkan pada jenis-jenis rangka kuda-kuda baja ringan yang lain. Dari penelitian ini didapatkan hasil berdasarkan pemodelan secara analitis dari beberapa tahap bentuk dari rangka kuda-kuda baja canai yang ditemukan, yakni bentuk rangka Fink yang dimodifikasi dengan batang horizontal dengan tipe F1 pada proses modifikasi. Pada tahap selanjutnya yakni proses kombinasi rangka tidak mencapai bentuk yang optimum. Lendutan maksimum pada pemodelan secara analitis yakni sebesar 11.17 mm pada beban 2250 kg. Sedangkan pada pemodelan prototipe lendutan maksimum yang terjadi sebesar 11.33 mm pada beban 1270.99 kg dan didapatkan hasil angka keamanan yang direkomendasikan sebesar 1,4. Untuk pola keruntuhan keruntuhan yang terjadi, pada ½, ¼ bentang terjadi tekuk torsi, dan pada bagian tumpuan terjadi tekuk lentur torsional.Kata-kata kunci: Baja Canai dingin, Rangka Atap, Kuda-Kuda, Bentuk Rangka Optimum.Abstract:The growth or increase in Indonesia’s population is very rapid resulting in the increasing number of residential needs which are also increasing. At present development such as apartments and housing is very much in the urban areas due to increasing population, or migration from rural to urban areas to compensate for population growth. Many houses built in housing use light steel frames as roofs. Roof truss material is usually made of wood, concrete, steel and mild steel, each of which has advantages and disadvantages. In this case the material mild steel easel has many advantages compared to other materials in previous studies. Several types of frames for cold rolled steel include Howe, Pratt, Fan, Fink, Scissors etc. For this reason, it is necessary to optimize the forms of lightweight steel truss, to find the optimum, safe, economical and efficient frame form. This study aims to obtain the maximum optimum form of light steel frame trestle, to know the maximum load, maximum deflection in frame configuration, safety figures and the collapse pattern of light steel frame truss due to static load, so that it can be used as a reference to be applied to other types of light steel frame truss. From this study the results obtained are based on analytical modeling of several stages of the shape of the form of rolled steel horses which are found, namely the shape of the Fink frame modified with horizontal rods with type F1 in the modification process. In the next step, the process of combining skeletons does not reach optimum shape. The maximum deflection in analytical modeling is 11.17 mm at a load of 2250 kg. Whereas the maximum deflection modeling that occurred was 11.33 mm at a load of 1270.99 kg and the recommended safety figure was 1.4. For the pattern of collapse that occurs, at ½, ¼ the span of the torsion bend occurs, and in the pedestal the bending torsional bending occurs.Keywords: Cold Rolled Steel, Roof Truss, Easel, Optimum Frame Shape

Residual stresses in cold extruded parts play an important role in both component lifetime and succeeding in manufacturing performance. When a cold extruded part is used directly, the lifetime of the part depends on the residual stresses induced during cold extrusion. On the other hand, if the part is exposed to post operations such as machining, residual stresses may cause distortions. Despite their importance, there are only a few residual stress measurement methods to assess axial residual stresses in full cylindrical thick components of massive forming. As high-energy X-ray and neutron diffraction methods are less available and considerably expensive, the contour method may be an alternative providing the accurate assessment of residual stresses without requiring specialized facilities. In the present work, residual stresses in cold extruded rods are determined via the contour method for various extrusion ratios. The finite element analyses for the same conditions are also carried out to provide the comparison to the contour method. The results indicate that the contour method can be a valuable candidate for the measurement of axial residual stresses in cold extruded thick components.

Most of the commercial metallic materials undergo at least one hot deformation stage during fabrication. Hot deformation processing leads to the production of plates, strips, rods, pipes and other shapes at lower overall cost when compared to the cold deformation/annealing route. Comprehensive study of the metallurgical phenomena during hot deformation has enormous potential application in the control of industrial rolling processes. Understanding of the microstructural and mean flow stress evolution lead to sound steel developments and innovative rolling schedules. The models predict parameters such as grain size, fractional softening (static and dynamic) and strain induced precipitation which are useful to improve rolling schedules. Effects such as incomplete softening and strain accumulation can be easily detected as well as their consequences on the final grain size and mechanical properties. In this regard, special attention must be given to steels, the most important metallic material in terms of history, present and future. In this paper, three hot rolling routes will be analyzed in order to produce high strength linepipe steels. Examples were selected on how the use of modelling during development stage can help to meet mechanical properties, mainly toughness and drop weight tear test. Firstly, it is presented a brief overview on mathematical models applied to hot rolling. Thin slab casting/direct rolling, hot strip mill and plate mill are exemplified in the present work. The development of new steel grades can greatly accelerated with the aid of modelling, which is an useful, low-cost technique.

The aim of the work is to study modern methods of production in the world of corrosion-resistant and fire-resistant high-strength reinforced rolled steel, designed for pre-stressed reinforced concrete structures. The specific cost of reinforcement is determined by the ratio of its value to the design resistance and decreases with increasing strength class. In Ukraine, economically alloyed steel grades are used for the production of prestressed high-strength reinforcing steel with a diameter of 6-40 mm of periodic profile according to DSTU 3760: 2019. It is also possible to use thermal strengthening of rolled products from rolling heating in the rolling mill stream, or from special (separate) heating. Hardening, tempering and also cold deformation of smooth profiles with the subsequent drawing of a periodic profile are also applied. According to the Interstate GOST 34028-2016 for the countries of the Customs Union, high-strength reinforcing steel of periodic profile of class A600p is made in bars and skeins with a diameter of 10-40 mm, and classes A800 and A1000 only in bars with a diameter of 10-40 mm from low-alloy steel grades. Depending on the diameter of the reinforcing steel, different production methods are used. GOST 34028-2016 contains clear requirements for corrosion resistance and methods of its testing. Many foreign requirements for the production of high-strength prestressed reinforcement, depending on the diameter of the profile (6-50 mm) and the method of production use carbon steels with different maximum carbon content from 0.37 to 0.8%, maximum silicon content from 0.55 up to 2.0% and a maximum manganese content of 1.8 to 2.0%. Thermomechanical reinforcement of reinforcing steel from rolling heating in the flow of rolling mills, hardening from separate (special) heating followed by tempering and strengthening by mechanical extraction followed by low-temperature tempering are used. Corrosion is the main cause of damage and destruction of reinforced concrete structures and buildings of prestressed reinforced steel from carbon steels. This problem in the world today is solved with the use of stainless steels, which have high corrosion resistance and fire resistance. Prestressed stainless steel reinforcement has higher strength and, especially, ductility than carbon steel. Stainless steel grades are used for the production of prestressed reinforcing steel with a diameter of 5 to 75 mm. In the production of periodic profiles of stainless steel reinforcement, there are two main technological routes: hot rolling and cold rolling. A promising way is the use of controlled hot rolling and thermomechanical treatment. As the rolling temperature decreases, the hardness of the austenite phase increases. For two-phase stainless steels, this allows to achieve high strength and ductility. Examples of the use of prestressed high-strength rebar in the world are: the construction of sealed shells that prevent the release of radioactive substances into the environment in severe accidents at nuclear power plants; construction of tanks for nuclear waste; construction of offshore platforms for oil production; construction of sea and river bridges, long-span ceilings, high-rise buildings, roads and other similar facilities.

Quasi-static/dynamic three-point bending tests were conducted to assess the crash performance of magnesium alloy AZ31B extruded and sheet tubes at the German Aerospace Centre (DLR) – Institute of Vehicle Concepts in Stuttgart. Different foam-filled AZ31B beams with a variation of foam density and thickness were fabricated through several manufacturing processes: cold bending, tungsten inert gas welding, cathodic dip painting and polyurethane foam injection. The experimental results were compared with those from mild steel DC04 tubes. It shows that empty magnesium alloy AZ31B outperforms steel DC04 in terms of specific energy absorption for the empty tubes with equivalent volume when subjected to bending loads. It was found that the foam-filled tubes achieved much higher load carrying capacity and specific energy absorption than the empty tubes. Moreover, there is a tendency showing that a foam-filled beam with a higher foam density reaches higher load carrying capacity, but fractures earlier. The foam-filled AZ31B tube with 0.20 g/cm3foam obtained the highest specific energy absorption, but this outperformance was weakened due to the earlier fracture. In addition, the numerical simulation utilising material model MAT_124 in LS-DYNA explicit FEA package was performed. The simulation results indicate that using calibrated stress-strain curves and failure parameters, material model MAT_124 yields a general good agreement with the experimental results.

Abstract Magnesium nanocomposites with improved mechanical and tribological properties have attracted widespread interest in the automotive sector. Given the great potential of magnesium nanocomposites in the automotive sector and the need to recycle materials to minimize their negative impact on the environment, it is imperative to consider the possibility of a practical approach to recycle these materials. In this study turning induced deformation technique is used to recycle the magnesium composites containing Iron Oxide (Fe3O4) nanoparticles. The chips collected from the turning process of composites were cold compacted and hot extruded into cylindrical rods. The extruded materials were investigated for their tribological response under dry sliding conditions. The wear tests were performed using a pin on disc tribometer against an EN31 alloy steel counter disc under applied loads of 10, 20, 30, and 50 N and sliding speeds of 1, 2, 3, and 5 m/s. The worn pin surfaces were examined under scanning electron microscopy integrated with an energy dispersive x-ray spectrometer to understand wear characteristics. The results revealed a better wear resistance and friction coefficient for recycled nanocomposites than pure magnesium. The enhanced wear resistance of recycled nanocomposites is attributed to the increased hardness and strength due to the Fe3O4 nanoparticles and the turning induced deformation process. The wear surfaces revealed abrasion and delamination as the predominant wear mechanism, with thermal softening occurring only at the highest applied load and sliding speed.

Abstract The objective of this work was to develop a procedure for evaluation and quantification of the tempering efficiency of corrosion resistant weld overlays used in the power generation and oil and gas industries. Three two-layer weld overlays of Alloy 625 on Grade 22 steel plates were produced using GTAW cold wire procedures. Typical welding parameters corresponding to low, medium, and high heat input were utilized. The overlays consisted of nine beads on the first layer and five to seven beads on the second layer. The weld thermal histories experienced in the coarse-grained heat affected zone (CGHAZ) were measured with Type K thermocouples and recorded with a 55 Hz sampling rate. Two rows of seven thermocouples were used in each overlay: one row located in a mid-bead position beneath the center bead of the overlay and the other row located in the nearest bead overlap position. Additionally, one Type C thermocouple was plunged into the weld pool of a second layer weld bead. The acquired thermal histories and the CGHAZ hardness at the thermocouple locations were evaluated to quantify the tempering efficiency in each welding procedure. The weld thermal histories with peak temperatures between 500°C, assumed as the minimum tempering temperature, and the base metal AC1 temperature were considered as tempering thermal cycles. The number of tempering thermal cycles and the sum of tempering cycle’s peak temperatures in each thermocouple location, as well as the corresponding hardness were used to quantify the tempering response efficiency for each of the three welding procedures. The results of this study will be used for validation of a computational model-based approach for prediction of tempering response and optimization of temper bead welding procedures.

Most of the BWR reactor pressure vessels have control rod drive hydraulic return (CRDHR) line nozzles. Each vessel has one such nozzle, typically 3–4 inches in diameter, and generally located 68–100 inches above the top of the active fuel. The CRDHR line was designed to provide a reactor pressure reference to the CRD system and to return to the reactor vessel exhaust water from CRD movement and water in excess of system requirements. The horizontal section of the piping near the CRDHR line nozzle is susceptible to thermal striping. Many of the BWR plants have capped this line. Recently at an overseas plant that had not capped this line, an axial through-wall fatigue crack of approximately 1-inch length was observed at the safe end connected to this nozzle. Based on this overseas operating experience (OE), a domestic plant that also did not cap the line developed a comprehensive analysis, inspection and repair plan to address the OE. Thermal-hydraulic and leak-before-break (LBB) evaluations were conducted to justify continued plant operation at this plant until the upcoming planned mid-cycle maintenance outage when the inspection of the line could be conducted and if necessary any repairs/modifications could be implemented. A thermal-hydraulic model was developed considering the geometry, the density difference between the hot and cold streams, the frictional and local losses, and the external flow effects, to predict thermal stratification. The model was validated against the test data from a foreign and a domestic BWR plant. This model was conservatively applied without taking any credit for the external flow and predicted that at the typical flow rates at the plant, thermal stratification in an approximately 45-inch long horizontal segment of the piping cannot be ruled out. However, later plant testing showed that thermal stratification does not appear at 20 to 26 gpm of cold injection flow, and the model predicts the plant testing when a moderate external flow effect is considered. The model determined a flow rate that would eliminate the phenomenon. However, the hardware limitations precluded the increase in the flow rate. The question that needed to be addressed was whether any fatigue cracking initiated from the previous operation could lead to failure of the affected piping segment during operation until the next refueling outage. The piping material is Type 304 stainless steel with a nominal diameter of 3-inches. Several LBB evaluations were conducted assuming different levels of part through-wall and through-wall cracking. Limit load equations of Appendix C of ASME Section XI were used to calculate the limiting critical crack lengths and depths. The leak rates were calculated using a modified two-phase flow model. The LBB evaluations concluded that short-term plant operation to next refueling outage is justified. The inspection findings, the temperature monitoring hardware installation, and the monitoring results obtained during the mid-cycle outage are also discussed.