Application possibility of arc welding processes for long butt joint of 75Mn steel plates without preheating

Abstract In order to ensure the stability of the track mechanical device, this paper solves the problem of attaching the lock flange to the side of the rail. This paper studies an arc welding process for long butt joint of high carbon 75Mn steel plates without preheating to assure the quality of weld and productivity. Using high manganese welding wire, and argon mixed with O 2 of 2.3% as shielding gas, resulted in preventing hot cracking and forming a good weld without defects. In addition, the effects of both preheating and post‐heat treatment by controlling the weld thermal cycle during a continuous double side welding process have been improved. The microstructures and mechanical properties of weld show that the metal inert gas (MIG) welding process is a dominant process in different ones. As a result, the formation of martensite microstructure was minimized, resulting in preventing cold cracking, and then getting a good quality of weld joint. During MIG welding 75Mn steel without preheating, the tensile strength, yield strength and elongation of welded joints are respectively 910 MPa, 576 MPa and 9.4%. Therefore, the mechanical strength of the joint was the same as that of the base metal.