Microstructure evolution in heat affected zone of T4003 ferritic stainless steel

摘要

In this work, microstructural characteristics and development within the heat affected zone (HAZ) of T4003 ferritic stainless steel (FSS) welded joint were investigated combining experimental measurement with finite element simulation of welding temperature field. The results indicate that the HAZ was characterized with heterogeneous microstructure due to the extensive peak temperature range which could be divided into three sub-zones named as HAZ1, HAZ2 and HAZ3. The HAZ1 (the region next to weld zone boundary) experienced peak temperatures of 1300-1500 ℃ during welding process. This region presented almost fully S ferrite microstructure with irregular grain, which was attributed to the high element diffusion rate and the absence of elevated-temperature austenite. The HAZ2 (center region of HAZ) suffered the peak temperatures of 1150-1300 ℃. It presented martensite + 8 ferrite dual microstructure with limited grain growth due to the formation of y phase at grain boundaries. The HAZ3 (the region closed to the base metal) was undergone the peak temperatures of 830-1150 ℃ and was characterized with both martensite and ferrite structure.