热输入对双相不锈钢管接头力学和腐蚀性能的影响

采用两种焊接工艺对双相不锈钢管道进行全位置焊接，对比研究了不同热输入条件下焊接接头的组织、力学性能和抗腐蚀性能，并用扫描电镜分析了缝隙腐蚀后蚀坑的组织特征。结果表明，焊接热输入是影响焊接接头相比例的一个重要参数，焊接采用高热输入时，尽管会使凝固组织铁素体晶粒易长大，但却会促使较多的奥氏体转变。同时相比例又影响着焊接接头的拉伸、冲击韧度等力学性能。蚀坑扫描电镜结果显示铁素体相优先被腐蚀，露出管状的奥氏体组织，这是由于合金元素在两相中的分配比例不同造成的电化学势差，进而形成局部选择性腐蚀。

Effects of heat input on mechanical and corrosion properties of du-plex stainless steel tubular welded joint

Duplex stainless steel pipes were all - position weldedby different welding procedure. Microstruetures, mechanical and corro-sion properties of the welded joints were investigated on condition of dif-ferent heat inputs. The test results show heat input is an important factorwhich has effect on phase ratio. It will lead to more transformation of aus-tenite with higher heat input. Meanwhile, phase ratio also has influenceon the mechanical properties such as tension, impact toughness of thewelded joints. The corrosion surface morphology and crystallographiccharacteristics of crevice corrosion pit were investigated by scanning elec-tron microscope(SEM). SEM observation reveals that ferrite is corrodedpreferentially and tubular austenite is uncovered. The occurrence of corro-sion is due to the disparity in the electrochemical potentials of ferrite andanstenite.