等离子弧焊Q345B和430不锈钢异种接头的微观组织与性能

摘要： 采用等离子弧焊对3 mm厚的Q345低合金钢与430不锈钢进行异种钢焊接，并对接头微观组织、力学性能及耐腐蚀性能进行了研究。结果表明,当转弧电流为100 A时，等离子弧焊Q345B/430异种钢接头的焊缝组织为均匀分布的马氏体及针状铁素体，焊接接头综合性能优良。随着电流的增大，焊缝组织转变为粗大板条马氏体及铁素体。两侧热影响区组织均发生一定程度的粗化，且Q345B侧热影响区出现魏氏组织。焊接接头于焊缝处显微硬度最大，不同转弧电流条件下异种钢显微硬度分布趋势大致相同。不同转弧电流下，焊接接头抗拉强度均与430不锈钢相近，且均断裂在靠近焊缝的430母材侧，转弧电流为100 A时接头抗拉强度最大值427 MPa。焊接接头的耐腐蚀性能与焊接电流呈负相关趋势。 创新点： 试验结果为铁素体低合金钢与铁素体不锈钢异种钢接头的应用提供了工艺数据与支撑。

Microstructure and properties of Q345B and 430 stainless steel dissimilar welded joints by plasma arc welding

Abstract: Plasma arc welding was used to butt welding of 3 mm thick Q345 low alloy steel and 430 stainless steel. Then microstructure, mechanical properties and corrosion resistance of welded joints were investigated. The results showed that when arc current was 100 A, microstructure in weld zone of plasma arc welding Q345B/430 dissimilar steel joints consisted of uniform martensite and acicular ferrite. The overall performance of welded joints was relatively superior. With the current increasing, microstructure of weld transformed into coarse lath martensite and ferrite. Microstructure of heat affected zone (HAZ) on both sides was coarsened in a certain degree, and Widmanstatten appeared in HAZ on the Q345B side. Weld had the maximum microhardness at the entire dissimilar steel joints, and the overall change trend of microhardness distribution of dissimilar steel joints were consistent under different arc currents. Tensile strength of welded joints under different arc currents and 430 stainless steel were equivalent, and all welded joints fractured at the 430 side near weld. When arc current was 100 A, tensile strength of welded joints reached the maximum value of 427 MPa. Corrosion resistance of welded joints was negatively correlated with welding current. Highlights: The experimental results provided process data and supports for the application of ferritic low alloy steel and ferritic stainless-steel dissimilar steel joints.