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分别对U20Mn2SiCrNiMo贝氏体钢轨和U75V珠光体钢轨的闪光焊接头进行了力学性能试验及对比。结果表明:贝氏体钢接头强度略高于母材,但塑性下降较为明显。贝氏体钢接头的平均抗拉强度为1404 MPa,断后伸长率为5.9%;珠光体钢接头的平均抗拉强度为925 MPa,断后伸长率为9%。贝氏体钢焊缝的平均冲击功为30.4 J,是珠光体钢焊缝(12.7J)的2倍以上。贝氏体钢母材的冲击功为110 J,是其焊缝的3.6倍。珠光体钢焊缝的冲击功与母材在相同水平。贝氏体钢轨闪光焊接头拉伸断口和冲击断口的缺陷是以沿晶裂纹为主,其次是焊缝夹杂物。珠光体钢轨闪光焊微观缺陷是以焊缝夹杂物为主,极少数情况下出现沿晶断裂。
The mechanical properties of the flash welded joints of U20Mn2SiCrNiMo bainite rail and U75V pearlite rail were tested and compared respectively. The results show that the strength of bainitic steel joint is slightly higher than that of base metal, but the plasticity is obviously decreased. The average tensile strength of the bainitic steel joint is 1404 MPa and the elongation after fracture is 5.9%. The average tensile strength of the pearlite steel joint is 925 MPa and the elongation after fracture is 9%. The average impact energy of bainitic steel welds is 30.4 J, which is more than twice that of pearlite welded joints (12.7 J). The impact energy of bainitic steel base metal is 110 J, which is 3.6 times of the weld. Impact energy of pearlite weld is at the same level as base metal. Bainitic rail flash welded joint tensile fracture and impact fracture is based on intergranular cracks, followed by weld inclusions. Pearlite rail flash welding microscopic defects are based on weld inclusions, in a very few cases along the crystalline fracture.