Recently, the development of technologies to reduce energy and protect the global environment of automobiles, aircraft, rail vehicles and ships has been actively underway. Lightweight technologies include efficient engine development, application of lightweight materials and structural rationalization. As part of reduce lightweight, it is used for ultra-high strength steel plates and steel materials is replaced by Al and Mg alloys.

Compared to steel materials, Al alloys have about four times the thermal conductivity, two times the specific heat and 1.5 times the melting latent heat. And the low melting temperature and difficult to concentrate energy in heat source. Also, The surface is easily oxidized and the formed aluminum oxide film has a high hardness and high melting point, so that it is difficult to remove.

In this study, AC pulse MIG welding process as a method for Al 6061-T6 to STS 304L lap joint. Study about Jointability of electrode wire position and welding current affect to Al 6061-T6/STS 304L lap joint.

Aluminum alloy Al 6061-T6 with 2mm and Stainless steel STS 304L with 3mm thickness are adopted as base metal in this study. The filler wire used 1.2mm diameter of ER5356. Welding current and electrode wire position were adopted as welding parameter. Welding current were 55, 65, 75, 85, 95, 105A and electrode wire position were A(STS side), B(STS/Al corner), C(Al top side). Al 6061-T6 and STS 304L lap jointed strength were came from joint interface and wetting angle. So measured joint interface length and wetting angel by cross sectioned macro specimen. Also, did the Shear-tensile test, and analysis joint interface length, wetting angle and shear-tensile strength. Additionally, did the SEM/EDS analysis for the formation of intermetallic compound amount and component change of electrode wire position and welding current.

As a result, electrode wire position A(STS side) is the best wire position and welding current is 75A. Which is highest shear-tensile strength(7.13kN). And intermetallic compound seems FeAl3, which is very brittle intermetallic compound.