Effect of TIG Process on Microstructures and Properties of 321 Stainless Steel Welding Joint

摘要

Different welding parameters were employed to investigate TIG-welding technology of 321 stainless steel. The microstructure and tensile fracture surface of its welding joint were observed by optical microscope (OM) and scanning electron microscope (SEM). Tensile test was conducted to assess the joint's mechanical property. The results show that, the microstructure of weld zone is composed of austenite matrix and ferrite. The size of grains grows up with the increase of heat input. With the increase of welding speed, the morphology of ferrite transforms from skeleton to lath-shaped and the quantity of ferrite increases significantly. Further more, side-plate ferrite becomes more slender and the joint strength increases with the increase of welding speed. With a suitable welding parameter (welding current of 170A, welding speed of 207mm/min), the weld shows better mechanical property with the max σp of 623 Mpa and δ of 49%.