Investigation of Aluminum-Stainless Steel Dissimilar Weld Quality using Different Filler Metals

摘要

Aluminum-stainless steel dissimilar welding processes yield unwanted disadvantages inudthe weld joint due to the large difference between the aluminum-stainless steel sheets’udmelting points and the nearly zero solid solubility between these two metals. AluminumudAA6061 and stainless steel SUS304 were lap-welded by using Metal Inert Gas (MIG)udwelding with aluminum filler ER5356 (Group 1) and stainless steel filler ER308LSiud(Group 2). The effects of the welding voltage and type of filler metals used on the weldudjoints were studied. The welding voltage had a significant effect on the welding process,udas higher voltage resulted in poorer appearance of the weld joint and led to defects forudboth groups, such as porosity and incomplete fusion. The microstructure for Group 1udjoints shows enrichment of Si particles, which benefited the joint properties as itudincreased the strength of the metal. The stainless steel substrates that spread into theudaluminum side are much greater in volume for Group 1 than for Group 2 joints.udMeanwhile, the microstructure of Group 2 joints (using ER308LSi filler) consists ofudchromium carbide precipitation which yields a high hardness value, but a brittleudstructure. The hardness values of the welded seams in Group 1 and Group 2 range fromud60 to 100 HV and 160 to 230 HV, respectively. The fracture in the tensile test yieldedudthe highest tensile strength of 104.4 MPa with aluminum fillers. The tensile strength ofudGroup 1 joints ranging from 47.8 to 104.4 MPa was collectively higher than Group 2udjoints, between 20.24 to 61.76 MPa. Based on the investigation throughout this study, itudcan be concluded that the welding voltage of 18 V and aluminum filler ER5356 is theudoptimum filler in joining the dissimilar metals aluminum AA6061 and stainless steeludSUS 304.ud