X80??????????????????????

粗晶区是焊接接头的薄弱环节.通过对X80管线钢进行热模拟、金相显微镜和透射电镜分析后表明,粗晶区的组织主要为板条束贝氏体和粒状贝氏体；X80管线钢焊接热影响区粗晶区冲击韧性较差,存在严重脆化,粗晶区脆化是由于晶粒的粗化以及M-A组元数量增多造成的；随着t8/5的增加,粗晶区的冲击韧性和硬度随之降低；峰值温度越高,X80级管线钢的组织越粗大、韧性越低；中间临界区是焊接热影响区中另外一个韧性较薄弱的区域.

Thermal Simulation Research on Welding Heat Affected Area of X80 Pipeline Steel

CGHAZ is weakness area of weld joint.After the investigation of thermal simulation,microscope and TEM,the results revealed that the main structures of CGHAZ were lath-shape bainite and granular bainite,the toughness of coarse-grain zone was weak,and brittle zone happened in coarse-grain zone.The low toughness of coarse-zone was ascribed to the coarse grain size and the increasing quantity of M-A components.With the increase of t8/5,the impact toughness and hardness of coarse-grain zone decreased.The higher the peak temperature is,the coarser the structure of the X80 grade steel and the lower the impact toughness.ICHAZ is another weak zone in HAZ.