BTi-62421s合金板钨极氩弧焊接头组织性能研究

研究了焊前热处理、焊接工艺及焊后热处理对BTi-62421s板材钨极氩弧焊接头组织性能的影响。结果表明: BTi-62421s合金板材钨极氩弧焊较佳焊接工艺为: 焊接电流110 A, 焊接速度5 mm/s, 主喷嘴氩气流量20 L/min, 拖罩氩气流量12 L/min, 单面焊接, 此工艺下双重退火态BTi-62421s合金焊接接头抗拉强度σ_b为1 033 MPa, 为母材的96.5%, 延伸率δ为5.5%, 为母材的38.5%; 焊缝组织为针状马氏体, 热影响区组织为初生α组织、β转变组织和针状马氏体组织; 合金焊前双重退火和去应力退火对焊缝组织组成影响有限, 但双重退火有助于焊接接头塑性的提高; 焊后热处理促进合金接头α'→α+β相转变, 有利于焊接接头塑性的提高, 较佳焊后热处理工艺为700 ℃/2 h, 空冷, 此工艺下双重退火态BTi-62421s合金焊接接头延伸率δ为7.1%, 为母材延伸率的49.5%。

Microstructure and Mechanical Properties of TIG Welded Joint of BTi-62421S

The effect of pre-weld heat treatment, welding procedure and post-weld heat treatment on the microstructure and mechanical properties of TIG welded joint on BTi-62421S plates was studied. Results show that preferable parameters for TIG welding of BTi-62421S plates are as follows: welding current of 110 A, welding speed of 5 mm/s, main nozzle argon gas flow of 20 L/min, drag cover argon gas flow of 12 L/min and with a single-side welding technique. With this approach, the tensile strength σ_b and elongation percentage δ for the welded joint of double annealed BTi-62421S reached 1 033 MPa and 5.5%, respectively, which was correspondingly 96.5% and 38.5% of the base metal. The weld seam metal was indentified as acicular martensite and the heat-affected zone was consisted of primary α phase, transformed β phase and acicular martensite. Although pre-weld heat treatment of BTi-62421S had little effect on microstructure of welded joint, the ductility of the joint could be improved by double annealing of BTi-62421S. The post-weld heat treatment promoted α'→α+β transformation, which was beneficial to enhance plasticity of the joint. And the preferable conditions for post-weld heat treatment of BTi-62421S were 700 ℃/2 h and AC, with which δ for the welded joint of double annealed BTi-62421S reached 7.1%, namely, 49.5% of the base metal.