توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Simulation of rolling pressure in hot rolling by Finite difference method
نویسنده(ها): ،
اطلاعات انتشار: اولین کنفرانس بین المللی و هفتمین کنفرانس ملی مهندسی ساخت و تولید، سال
تعداد صفحات: ۹
Accurate prediction of rolling forces as well as the dimentional variation of hot rolled sheets can be achieved by mathematical modelling of thermal and mechanical behaviour of material during hot rolling. The paterns of temperature, strain and the flow stress distribution are determined by heat transfer and plasticity models. In this work, a two dimentional heat transfer model is coupled with a simple upper bound model to calculate the roll presure ditribution across the sheet width. This is done by a 2D FDM which is utillized to solve the equation. The thermal model includes the conduction, convection and radiation before, during and after steady state rolling. The extracted model is unsteady state one and it is solved in implicit form. An upper bound velocity field is applied to explain material movement between the rolls and to calculate the strain rate and strain distribution at the roll gap. Finally, the pressure distribution along roll barrel is determined for rolls without crown by employing the proper boundary conditions. The results are compared with some measured data on a low carbon hot band rolling mill.<\div>

۲The effects of TiB2 particle volume fraction on the hot workability of TiB2\AA 2024 composites
نویسنده(ها): ، ،
اطلاعات انتشار: دومین کنفرانس بین المللی کامپوزیت، سال
تعداد صفحات: ۶
In this study, the hot workability of AA2024 composites reinforced with different volume fractions (4 and 8 vol%) of TiB2 particles was investigated by means of hot compression tests over a range of strain rates (0.006 – 0.6 s–1) and temperatures (350 – 500 °C). Dynamic recrystallization (DRX) or dynamic recovery (DRV) of the composites was studied from the flow curves and deformed microstructures. The deformation processing maps were constructed by superimposition of the contour plots of the power dissipation efficiency and the instability parameter. Optimum strain rates and temperatures for effective hot working of Al2024\TiB2 composites are selected as 450–500 °C with strain rates less than 0.02 s–1 based on the deformation processing maps.<\div>

۳Microstructure and Mechanical Properties of Al\Ni Composite Sheets Produced by Accumulative Roll Bonding (ARB)
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی کامپوزیت، سال
تعداد صفحات: ۶
In this work, fabrication of metal matrix composite sheets by accumulative roll bonding (ARB) process and their properties have been investigated. Due to excellent combination of properties and high strength, composite sheet materials have found great industrial applications. In this investigation, AA1100 matrix composites with nickel particle reinforcements were fabricated. It is shown that increase of strength and micro–hardness is accompanied by a sharp decrease of total elongation. Sharp edges of reinforcements caused proportional limit stress, that decreased by ARB process. As the ARB process proceeded, more uniform dispersion of reinforcements in the matrix is achieved, resulting in improvement of the ductility. Furthermore, accumulation of strain introduced ultra fine grains in the matrix and reinforcements.<\div>

۴Production of High Strength Al–Al2O3 Composite by Accumulative Roll Bonding
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی کامپوزیت، سال
تعداد صفحات: ۶
Recently accumulative roll bonding (ARB) has been used as a novel method to produce particle reinforced metal matrix composites. Due to combination of ARB processing and particle effect on microstructure, these composites have excellent mechanical properties. In this study, Al–Al2O3 composite was successfully produced and the effects of number of ARB cycles and the amount of alumina content on the microstructure and mechanical properties of the composites were investigated. According to results of the tensile tests, it is shown that the yield and tensile strength of the composite is increased with the number ofARB cycles. Scanning electron microscopy (SEM) reveals that distribution of the alumina particles is improved by increasing the ARB cycles. It is also found that the tensile strength of the composite as a function of alumina content has a maximum value by 2.5 wt.%, which is 5.1 times higher than the annealed aluminum.<\div>

۵effect of laser welding conditions on properties of steel tailor welded blanks TWB
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۷
there is a major interest to manufacturers of automobile and aerospace parts towards the tailor welded blanks TWBs to reduce the weight and cost of the parts and improve their perfomance in this work effet of laser welding parameters such as power speed angle of the laser beam and the focused length on properties of four groups of TWBs two groups with similar thickness and different steels and two groups with similar steel and different thicnesses are investigated the results indicate that the inclined laser beam cause the sample failure from the weld zone in the tensile test setting the focal poit on the top surface of the sheets results in better properties in compariston to the other positions due to high cooling rate at weld zone microstructure of the weld aminly consists of acicular ferrite widmanstatten ferrite allotropic ferrite and to some extent low carbon bainite which in turn lead to higher strength in welded sheets comparing to the as received ones<\div>

۶influence of friction stir welding parameters on mechanical properties of aluminum tailor welded blanks with different thickness ratios
نویسنده(ها): ، ،
اطلاعات انتشار: کنگره بین المللی جوش و روشهای اتصال، سال
تعداد صفحات: ۶
welded sheets with different thicknesses are one of the major kinds of tailor welded blanks TWB which are widely used in metal forming industries . In the present work effects of friction stir welding FSW parameters and thickness ratios on mechanical properties of thin aluminum tailored sheets are studied thickness ratios for these set of welded blanks are 1,1.33 and 1.67 .quality size and shape of stirred zone were studied by metallographic examination of weld nuggets results indicate that increasing the welding rotational speed rpm with a constant weldeing traverse speed v cm\min leads to increase of the nugget size and decrease of the defects.<\div>
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