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Abstract
In this paper, the high-temperature creep strengths and microstructures of laser beam and tungsten inert gas (TIG)-welded HR3C austenitic stainless steel joints were investigated. The results show that the high-temperature creep strengths of laser joints are increased compared with TIG joints with post-weld treatment. In laser welding joints, the microstructure is fine cellular austenite grains with a few fine globular austenite grains growing almost symmetrically along the bead centre, and no residual δ-ferrite is observed. However, about 8% of residual δ-ferrites occurred in the TIG joints. With a solution-annealing treatment, the δ-ferrites of TIG joints are dissolved, and the austenite grains are coarse in the weld bead. The improvement in creep strength of laser welding joint mainly comes from the low heat input and high welding speed, which can induce a fast solidification of the weld pool; therefore, no δ-ferrite is formed in this process.