Effect of welding parameters and post-welding heat treatment on the microstructure and properties of weld seam of 20# steel and 304 stainless steel

According to the influence of welding process between 304 austenitic stainless steel and 20 steel dissimilar steel on the weld seam, the effects of welding current of 150A, 180A and 200A, normalizing and solution treatment on the microstructure and properties of the weld seam were studied by using MAG. The results show that the 150A current welding seam has incomplete fusion, which leads to its low strength and fracture toughness. With the increase of current, the necking fracture occurred on one side of 20 steel, and the brittleness and hardness of weld increased, all of which indicated that carbon element diffused from 20 steel to weld and 304 stainless steel. Although the corresponding post-welding heat treatment can reduce the hardness to a certain extent, improve the machining performance of welded joints and homogenize the microstructure of welded joints, it can’t significantly improve the performance of welded joints of dissimilar steels.