摘要
利用焊接热模拟技术,通过光镜、环境扫描电镜和力学试验分析,研究了焊接热循环中t8/5对X70级管线钢粗晶区性能的影响。结果表明,随着t8/5的增加,粗晶区硬度逐渐减小,贝氏体化铁素体粗化,且其间的M-A组元由条状转变为块状,平均弦长增加,体积分数增大,奥氏体晶界M-A组元增多变粗,管线钢的韧性恶化,抗裂性变差,冲击断口扩展区呈脆性断裂。当t8/5=20s时,试样的起裂区可观察到大量的韧窝,具有较好的冲击韧性值。
The effect of t8/5 on CGHAZ performance for X70 pipeline steel in the thermal simulation was studied by welding thermal simulation technology and through optical microscope,ESEM and mechanical test.The results showed that the hardness of CGHAZ is decreasing,bainite ferrite strip coarsens,the shape of M-A constituents transforms strip into block,its size becomes large,and its bulk extends,with increasing of t8/5.In addition austenitic,M-A constituents in γ grain boundary coarsens and manifolds with increasing of t8/5.They all deteriorate the toughness of pipeline.And the extended zone of impact fracture shows brittle.When t8/5=20 s,a lot of dimple can be shown at the beginning of specimens' fracture,and it is with good toughness.
出处
《焊管》
2008年第6期22-26,共5页
Welded Pipe and Tube
关键词
X70级管线钢
热模拟
粗晶区
M—A
X70
thermal simulation
coarse grain zone
M-A constituents
