为了改善大直径中空45#钢棒材的连续驱动摩擦焊接性,采用二级加压方法进行了外径42 mm,内径26 mm的45#钢连续驱动摩擦焊接.试验结果表明,焊接热输入随着摩擦时间、旋转速度的增大而增大,当摩擦时间较短、旋转速度较低时,采用较大的顶锻力、二级摩擦力不能显著增加焊接热输入,导致无法顶锻,产生严重的焊接缺陷.对于无缺陷接头,接头最大强度系数达到80.9%,接头中未发现熔化现象,焊缝发生动态再结晶,热机影响区和部分正火区出现魏氏体组织.接头冲击试验发现,力学性能优异的接头薄弱区位于部分正火区,而焊接热输入较高的接头薄弱区位于热机影响区.焊接热输入较低难于获得缺陷的焊接接头,焊接热输入过大显著降低接头力学性能.%Secondary pressured system was adopted to promote the directive friction welding feasibility of 45#steel hollow rods with the outer and inner diameters of 42 and 26 mm respectively. The results showed that the welding heat input was increased with the increasing friction time and rotation speed. Welding heat input could not be increased effectively by increasing the upsetting force and the secondary pressured friction force at short friction time and low rotation speed. Thus, massive deformations cannot be obtained resulting in severe welding defects. For defect free joints, the maximum coefficient of the joint strength reached 80. 9%. The melting phenomenon was not observed but dynamic recrystallization occurred in the joint. Widmanstatten microstructure was observed in the thermal mechanically zone and the partially normalized zone. The results of the impact test indicate that the poorest zone of the joints with better mechanical properties lies in the partially normalized zone and the poorest zone of the joints produced by using the higher heat input is located in the thermal mechanically zone. Defect-free joints cannot be obtained at the low heat input, and mechanical properties of the joints will be obviously decreased at much higher heat inputs.
展开▼
