علی مهدوی شاکر - Faculty of Materials & Manufacturing Technologies, Malek Ashtar Univ. of Technology, Tehran, Iran.
حسین مومنی - Faculty of Materials & Manufacturing Technologies, Malek Ashtar Univ. of Technology, Tehran, Iran.
علی خرم - Faculty of Materials & Manufacturing Technologies, Malek Ashtar Univ. of Technology, Tehran, Iran.
علیرضا یزدی پور - Faculty of Materials & Manufacturing Technologies, Malek Ashtar Univ. of Technology, Tehran, Iran.

This study aimed to investigate the effect of electron beam welding parameters on the microstructural characteristics and mechanical properties of the dissimilar joint between ۱۷-۴PH precipitation hardening stainless steel and Ti۶Al۴V alloy. For this purpose, the welding of these two alloys was done without an interlayer and with an interlayer of copper with a thickness of ۰.۸ mm. Two different welding speeds of ۰.۷ and ۰.۹ m/min with four levels of beam offset  (۰, ۰.۲, ۰.۴ and ۰.۶ mm) from the center of the interlayer towards the steel were used to perform experiments. The results show that in the direct welding of titanium and steel, the joint structure consists of TiFe and TiFe۲+TiCr۲ intermetallic compounds with high hardness (about ۹۰۰ Vickers). In the welding of titanium and steel by using the copper interlayer, the structure in the weld pool and the interface between the weld pool and steel includes a solid solution of copper and TiFe۲ intermetallic compounds, and at the interface between the weld pool and titanium includes Ti+Ti۲Cu and TiFe. The hardness of the welding zone in the samples welded with copper interlayer is about ۴۰۰ Vickers. The highest value of hardness is observed at the interface between the weld pool and titanium alloy, as well as at the interface between the weld pool and steel, which is due to the presence of intermetallic compounds with high hardness. By increasing the welding speed and beam offset, the hardness decreases, which is due to the reduction of brittle intermetallic compounds in the joint structure. The welded sample with a welding speed of ۰.۹ m/min and beam offset of ۰.۶ mm has the highest shear strength equal to ۱۶۰ MPa.

Electon Beam Welding, ۱۷-۴PH Steel, Ti۶Al۴V alloy, Cu interlayer, Microstructure, Mechanical properties, جوشکاری پرتو الکترونی, فولاد زنگ نزن ۱۷-۴PH, آلیاژTi-۶Al-۴V, لایه میانی مس, ریزساختار, خواص مکانیکی