Metallurgical, mechanical and corrosion behaviour of pulsed and constant current TIG dissimilar welds of AISI 430 and Inconel 718

Abstract

This research work explore the weldability, structural integrity, mechanical properties and corrosion behaviour of dissimilar welds of Inconel 718 and AISI 430 developed by using constant and pulse arccurrent modes in TIG welding process. The welded structures defects for inspected by employing X-ray radiography images as well as macrostructures. Metallurgical changes were observed using optical & scanning electron microscope techniques. Mechanical properties of the joined structures were evaluated by performing tensile test on UTM and hardness measurements on weld surfaces using Vickers hardness tester. The resistance against the corrosion especially at the weld area of both welded structures was measured. The joined structures were free from flaws and also seen the uniformity of the filler distribution towards the base metals. The grain coursing with well-defined grain structures were identified in CC-TIG weldmentswhereas fine grains with clear distribution of filler alloying elements were seen in PC-TIG weldments. PC-TIG weldments exhibited with better mechanical and corrosion resistance properties than the CC-TIG weldments vowing to pulse arc mode during welding process. The aerospace and nuclear industries will benefit from the study's findings especially turbine disc and shaft assembly.

Keywords

• Ni-based super alloy
• Ferritic stainless steel
• Constant and pulse arc welding
• Metallurgical changes
• Mechanical properties
• Corrosion studies