Abstract
Dissimilar welded joints of Fe-Cr-Al alloy (23Cr-7Al) and AISI 310 austenitic stainless steel (25Cr-20Ni) were studied and characterized, before and after the isothermal heat treatment (IHT) of oxidation at 1150°C for 936h in air. The Fe-Cr-Al alloy was used as the welding consumable and the welding process used was gas-shielded tungsten arc welding (GTAW) with currents of 60, 80 and 130amps, and welding speed 1, 1.1 and 1.3mm/s. In the heat treated specimens, pore formation was observed as well as significant variations of Al contents in all-welded metals and formation of protective layer of alumina-Al2O3 on the oxidized surfaces particularly in the sample 1, welded at 60amps and welding speed of 1mm/s, that showed higher pore index and a greater deflection in the decrease of the Al content. The formation of Kirkendall pores occur due to the rapid diffusion of the aluminum from the all weld metals to the AISI 310 austenitic stainless steel, as was detected by the sample 1 mainly and especially by identifying the chromium content of the dissimilar alloy and the stainless steel.
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