摘要
焊接热影响区粗晶区是焊接接头中薄弱的区域。本文采用焊接热模拟技术、显微组织观察和力学性能测试研究了X100管线钢焊接粗晶区的组织和性能的变化规律,讨论了冷却时间、组织和性能之间的关系。研究表明,焊接粗晶区组织主要由粒状贝氏体组成,随着冷却时间t8/5的延长,晶粒变粗大,贝氏体化铁素体粗化,M-A组元体积分数增大,并由条状变成块状,晶界上M-A组元也变得粗大,导致冲击韧性下降,抗裂性变差,冲击断口形貌脆性断裂的比例越来越大,且硬度、屈服强度、抗拉强度逐渐减小。
The CGHAZ(Coarse Grain Heat Affected Zone) is the weak part of welded joint. In the paper, the change of microstructure and properties of CGHAZ of X100 pipeline steel was studied by welding thermal simulation method, microstructure observation, mechanics performance testing. The relationship between cooling time, microstructure and properties was discussed as well. The results indicated that the CGHAZ was mainly composed of granular bainite, with the increase of cooling time, grain size and bainite ferrite coarse, the volume fraction of M-A component increased, the shape changed from strip to chunk at the same time, M-A component on the grain boundary also coarsened, all of the phenomenon aforementioned lead to the decrease of impact toughness and crack resistance. The proportion of brittle fracture in impact fracture morphologywas becoming increasingly larger and the hardness, yield strength and tensile strength descended.
出处
《焊接技术》
北大核心
2014年第2期13-18,7,共6页
Welding Technology
