X80管线钢焊接热影响区组织和性能分析

采用焊接热模拟技术和金相显微组织分析技术,对首钢研制开发的X80热轧板卷在不同焊接热循环下的组织和力学性能变化规律进行了深入分析.结果表明,粗晶热影响区是X80管线钢焊接热影响区中冲击韧性较差的区域,存在严重脆化.粗晶热影响区脆化是由于晶粒的粗化以及粒状贝氏体、上贝氏体、M-A组元等非平衡中低温转变产物数量增多造成的,且其冲击韧性随着t8/5的增加而降低.细晶热影响区是X80管线钢焊接热影响区的软化区域,软化程度随着焊接热输入的增加而增加.

Microstructure and mechanical properties of heat affected zone for X80 pipeline steel

The thermal simulation and microstructure a-nalysis technology were used to investigate the microstructure and mechanical properties of the heat affected zone for X80 pipeline.Results indicated that the toughness of coarse-grain zone and crit-ical heat affected zone in X80 pipeline HAZ were weak.Brittle zone happens in coarse-grain zone.The low toughness of coarse-zone was ascribed to the coarse grain size,the increasing quanti-ty of granular bainite and upper bainite as well as other unbal-ance low and middle temperature transformation products.The impact toughness of coarse-grain zone decreases with the increase of t_8/5 Fined-grain zone is the softening zone in HAZ,the sof-tening degree increases with the increase of heat input.