Study On Regularity Of Austenitic Stainless Steel Weld Toughness And Microstructure

The paper studied regularities of austenitic stainless steel weld joints low-temperature toughness and micro structure before and after strain-strengthening processing.1.4301, AISI 304, 06Cr19Ni10 austenite stainless steels were selected as base metal; Manual metal arc welding (SM), tungstic electrode argon arc welding (GT), submerged-arc welding (S), plasma/tungstic electrode argon arc welding (P/T), tungstic electrode argon arc welding/manual arc welding (GT/SM), tungstic electrode argon arc welding/submerged-arc welding (GT/S) were used as welding methods; according to the equal components principle,the welding materials were selected. After weld, strain-strengthening processing was carried to austenite stainless steel weld joint. Then tensile test, impact test, bend test was conducted on austenite stainless steel weld joints before and after strain-strengthening processing. At last, according to austenite stainless steel weld joints mechanical properties and metallographic picture, the paper studies and summaries regularities, Results showed:strain-strengthening processing can improve significantly strength of austenitic stainless steel weld joints, yield strength Rpo.2 had increased by 39-58%.P/T weld joints had excellent mechanical properties; impact values of GT and slab S weld joints were compliance,but tensile datas floated up and down in standard value; tensile and impact value of SM,sheet S weld joints can't meet standard requirements.Different welding methods corresponded to different ferrite growth direction, morphologies and distribution which formed on the weld joints austenitic matrix. Ferrite growed perpendicular to base metal thickness in P weld joints, its morphology was small skeleton which uniformly distributed second equiaxed grains, and ferrite paralleled to base metal thickness in other welding methods'weld joints, GT weld will appear a certain amount of acicular ferrite, and most of ferrite morphologies were similar to SM and S weld, they were usually skeleton, lath, worm and globular.If ferrite dendrites were interconnected like network, it would split seriously austenite matrix, then weld joints plasticity and toughness decreased;Even if ferrite dendrites appeared solid solution affected by multi-layer and multi-pass welding thermal cycle, original morphology had no chang;.