高强度低焊接裂纹敏感性钢焊接热影响区的冲击韧度

采用埋弧自动焊接方法焊接高强度低焊接裂纹敏感性钢,分析了高强钢焊接热影响区中不同微区的显微组织特征与冲击韧度之间的关系.焊接接头粗晶区和细晶区的显微组织分别为粗大的粒状贝氏体和细小的准多边形铁素体组织,其-20℃的平均冲击吸收功分别为45 J和170 J.粗晶区中粒状贝氏体的有效晶界为原始奥氏体晶界,晶内存在大量的小角度晶界和亚晶界,有效晶粒尺寸较大,冲击韧度显著降低;细晶区中准多边形铁素体的平均有效晶粒尺寸约为5.3μm,大角度晶界可以有效阻碍了裂纹的扩展,具有较好的冲击韧度.

Toughness of welding heat affected zone in high strength steel with low welding crack susceptibility

In this study,the submerged arc auto-welding technique was employed to weld the high strength steel with low welding crack suceptibility.The relationship between microstructural feature and toughness in different sub-zones of heat affected zone was analyzed in details.The results showed that the main microstructures in the coarse grained zone and fine grained zone are coarse bainite and fine quasi-polygonal ferrite,respectively.And corresponding average impact absorbed energy is 45 and 170 J,respectively.Electron back scattering diffraction(EBSD) analysis showed that the effective grain boundary of coarse bainite is prior austenite grain boundary and a number of sub-boundaries and dislocation exist inside the grain.The coarse effective grain size reduces the toughness of coarse grained zone.On the contrary,the average effective grain size of quasi-polygonal ferrite in the fine grained zone is about 5.3 μm.High angle grain boundary inhibits the propagation of crack and improves the toughness.