A carbon steel ASTM 235JR covered with 4 mm layer of 316L stainless steel was welded using GTAW process. Two procedures were applied. The first one is to start welding of 316L layer using AWS A5.9 ER316Lfiller and then deposit of carbon steel using AWS A5.18 ER70S-6 filler wire on the 316L stainless steel weld metal. The other one is to weld the carbon steel substrate first and then deposit 316L stainless steel using AWS A5.9 ER316Lfiller on carbon steel weld metal. Starting from stainless steel side followed by deposition of carbon steel weld metal on 316L weld metal resulted in a joint with unaccepted bending test and v-notch impact toughness results. The microstructure at the interface of the joint welded with this procedure shows the existence of grain boundary type-II cracking and martensite layer. The average micro-hardness of the martensite layer is about 380 HV. The other procedure shows accepted bending and v-notch toughness results. This can be attributed to the absence of grain boundary type-II cracking at the interface of the welded joint using this procedure as observed at the microstructure of this zone. A martensite layer with micro-hardness value of 380 HV is also observed using this procedure. These results prove that the unacceptable bending and impact results is due to the formation of grain boundary type II cracking and not the formation of martensite structure.
 
Special Issue of AEIC 2024 (Mechanical & Chemical and Material Engineering  Session)