The aim of this article is study of tool plunge depth (TPD) effects on mechanical properties of friction stir welding of AA1100 aluminium alloy to A441 AISI steel. For this purpose the 0.1, 0.2, 0.4, and 0.6 mm TPD selected and other welding parameters kept constant. The results shows that the frictional heat increases and stir zone grain size decreases with increasing TPD at both base metals. At higher TPD, the material press out from shoulder and base metals interface. The highest tensile strength allocated to the joint which welded whit 0.2 mm plunge depth. This joint had appropriate joint efficacy, material flow and microhardness compare other joints. تفاصيل المقالة

In this paper, welding feasibility between AA1100, AA5050 and AA6082 aluminum alloys and A441 AISI steel by friction stir welding has been studied. Mathematical analysis of the heat generation during process showed that the maximum temperature produced in AA6082 aluminum alloy and A441 AISI joint but heat distribution in AA1100 aluminum alloy was higher than the other alloys. The investigation on joints windows concluded that the connecting link between AA1100 and A441 AISI steel was without any defect. Because of improper heat production and distribution in other joints, small tunnel was formed in the joints lower zones. Due to the softness of aluminums rather than steels, in tensile tests all joints were broken from the aluminum base metals. Strongest weld belonged to AA5050 aluminum alloy and A441 AISI steel joint that was about 84% of the aluminum base metal strength. Maximum joint efficacy based on A441 AISI has its place to AA6082 to A441 weld. Microhardness tests shows that welding line between AA1100 aluminum alloy and A441 AISI steel is harder that other joints. تفاصيل المقالة

High demands of quality development in the industry especially automotive, necessitates multi-objective optimization of the manufacturing processes. Fuel cells are one of the most important sources of renewable energies that Bipolar Plates (BPPs) are their main components. Metallic BPPs are known as a suitable replacement of the graphite plates due to their lower weight and cost. Accordingly, this study employs Multi-Criteria Decision Making (MCDM) methods to determine the best forming condition in the stamping of titanium BPP. In the first step, the process is analyzed using the Finite Element (FE) simulation. Afterward, validation of the FE model is confirmed by performing the experiments using titanium ultra-thin sheet with a thickness of 0.1 mm. Subsequently, a set of tests with 15 experiments are assumed to be as alternatives. In addition, filling ratio, thinning ratio and forming load are considered as different criteria. In order to select the optimum condition considering three mentioned responses simultaneously, TOPSIS and VIKOR methods are applied. In addition, a weighting procedure combining AHP and Entropy approaches is used. Based on the weighting results, the highest and lowest weights were obtained for filling ratio (0.5398) and forming load (0.1632), respectively. Likewise, a Spearman’s rank equal to 0.9357 was obtained that demonstrates high compatibility between TOPSIS and VIKOR methods. Overall, the best (optimum) forming condition has obtained an experiment with a clearance of 0.2 mm, the speed of 3.5 mm/s, and friction coefficient as 0.2. تفاصيل المقالة

In this article effects of friction stir welding (FSW) tool rotational and traverse speeds were studied on heat generation and temperature distribution in welding zone of AA1100 aluminum alloy and A441 AISI joint. Computational fluid dynamics method was used to simulate the process with commercial CFD Fluent 6.4 package. To enhance the accuracy of simulation in this Study, the welding line that is located work-pieces interface, defined with pseudo melt behavior around the FSW pin tool. Simulation results showed that with increase of FSW tool rotational speed, the generated heat became more and dimensions of the stir zone will be bigger. The calculation result also shows that the maximum temperature was occurred on the advancing side. The computed results demonstrated that with increasing tool linear speeds the heat generation experienced growth down trend. With increasing traveling speeds the time to reach maximum temperature in stir zone growth but the tool rotational speed dose not effect on time to reach maximum temperature. The model outcomes show that more than 85% total heat was produced by tool shoulder and the maximum heat with selected parameters in this study was 935 kelvin degrees. The computed results shows that the maximum value of strain rate achieved was 29 S-1 for A441 AISI side and 42 S-1 at AA1100 side. تفاصيل المقالة

در این پژوهش، اثرات پارامترهای مختلف جوشکاری اصطکاکی اغتشاشی در شکل گیری ترکیبات بین فلزی، عیوب و مقاومت کششی اتصالات آلومینیوم AA1100 به فولاد A441 AISI مورد بررسی قرار گرفت. در سرعت های جوشکاری پایین و سرعت های دورانی بالا، لایه های بین فلزی شکل گرفته ضخیم تر از حالت های دیگر بود. ترکیب این لایه هاAl6Fe و Al5Fe2 بود که در فصل مشترک دو قطعه کار شکل گرفتند. عمده عیوب شکل گرفته در این اتصالات عیوب تونلی و در سرعت دورانی پایین به دلیل تولید و توزیع حرارت نامناسب عیوب تونلی شکل گرفته با افزایش سرعت خطی و سرعت دورانی ابزار کوچک شدند. به دلیل تولید گرمای بیشتر در اثر افزایش عمق نفوذ ابزار عیوب داخلی کوچکتر شدند. با کنترل پارامتر های مکانیکی فرآیند و در سرعت دورانی 800 دور بر دقیقه و سرعت خطی 63 میلیمتر بر دقیقه و عمق نفوذ 2/0 میلیمتر مستحکم ترین اتصال تولید شد که در حدود 90 درصد فلز پایه ی آلومینیومی استحکام داشت. تفاصيل المقالة