DH36钢水下摩擦塞焊工艺及力学性能

Underwater friction taper plug welding process and mechanical properties of joints for DH36 steel

文中通过工艺试验研究了DH36钢水下摩擦塞焊工艺窗口及焊接接头的显微组织和力学性能．结果表明，在焊接转速较低时，焊接接头根部容易形成“未结合”焊接缺陷，提高焊接转速可有效避免缺陷的形成；焊接转速为7500 r／min、轴向压力在30～45 kN范围是较适宜的焊接工艺参数；焊接接头焊缝组织主要为板条马氏体和贝氏体，焊接热影响区的组织主要为贝氏体；焊接接头的拉伸性能和冲击性能均随焊接转速的提高有不同程度升高，但随轴向压力的变化不具有明显规律性；在较优的焊接工艺参数下（焊接转速7500 r／min、轴向压力40 kN）焊接接头屈服强度为370 MPa，抗拉强度为530 MPa，断后伸长率为22．5％，结合线处0℃冲击吸收功为42．5 J．

The present study focus on exploring the underwater friction taper plug welding process and the joints mechanical properties for DH36 steel. The results indicate that at lower rotating speed,lack of bonding defect would form in the weld. Increasing the rotating speed is helpful for improving the weld quality and avoiding the formation of weld defects. In such situation,proper welding parameters are recommended as the rotating speed of 7 500 rpm and axial force ranging from 30 to 45 kN. The microstructure in the weld zone is consist of bainite and martensite,and in HAZ is mainly of bainite. Both tensile and impact properties could be improved by increasing the rotating speed,however,no significant variation can be found by changing the axial force. Under proper welding parameters( 7 500 rpm rotating speed and 40 kN axial force) the weld would have excellent mechanical properties of 370 MPa yield strength,530 MPa ultimate tensile strength,22. 5% elongation and 42. 5 impact toughness at 0 ℃.