摘要
通过电子拉伸、硬度测试以及金相组织分析,对X70大变形管线钢焊接接头的力学性能及显微组织进行了深入研究。结果表明,X70焊接接头均断裂于焊缝附近(近缝区);X70焊接接头热影响区粗晶区存在明显的软化,焊接接头上表面硬度损失大于下表面,最大硬度损失达28 HV0.2,但下表面软化区宽度大于上表面。X70焊接接头热影响区粗晶区大量粗大的粒状贝氏体和准多边形铁素体的存在是导致焊接接头热影响区软化并断裂于焊缝附近(近缝区)的主要内因。
The mechanical properties and microstructure of the welded joints of X70 grade pipeline steel wereinvestigated by electronic tensile, hardness testing and optical microscopy. The results show that X70 steel cracks in thewelded joints. Softening exists in coarse grain HAZ of the welded joints of X70 grade pipeline steel. The highest hardness lossof upper surface in welded joint is 28 HV0.2, which is greater than that of the lower surface. The softening region in HAZ oflower surface is wider than that of the upper surface. The softening of coarse grain HAZ （CGHAZ） and cracking in the weldedjoints are attributed to the large number of coarse granular bainite （GB） and quasi-polygonal ferrite （QF）.
出处
《热加工工艺》
CSCD
北大核心
2016年第21期176-179,共4页
Hot Working Technology
基金
中国石油科技创新基金资助项目(2013D-5006-0602)
关键词
X70
力学性能
软化区
显微组织
X70
mechanical properties
softening region
microstructure
