X120管线钢焊接热影响区的模拟研究
Simulation Study on Heat Affected Zone of X120 Pipeline Steel
赵 辉1， 胡水平1， 武会宾1， 李太全2
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作者单位：1. 北京科技大学 高效轧制国家工程研究中心，北京 100083； 2.北京科技大学 冶金与生态工程学院，北京 100083
中文关键字：焊接热循环；局部脆化；X120管线钢；韧性
英文关键字：welding thermal cycle； local frangibility； X120 pipeline steel； toughness
中文摘要：采用焊接热模拟技术研究了焊接热循环对X120管线钢焊接热影响区的组织和性能的影响。结果表明，经过一次热循环峰值温度1300 ℃后，随着t8/5的增加，韧性显著下降，发生严重脆化；当t8/5不变，二次热循环峰值温度为600 ℃和1200 ℃时，韧性得到明显改善；当二次热循环峰值温度为800℃时，在原奥氏体晶界处形成明显的“链状”结构的网状组织，韧性有所下降；而当二次热循环峰值温度为1000 ℃时，局部脆化现象严重，这与冷却时获得含有粗大M-A岛状组织的粒状贝氏体有关。
英文摘要：The effects of welding thermal cycle on the microstructure and mechanical properties of heat-affected zone(HAZ) of X120 pipeline steel was studied by using welding thermal simulation. The experimental results indicate that when the peak temperature of thermal cycle is 1300 ℃, toughness value drops severely with the increase of t8/5 . While t8/5 is invariable, it can obtain good toughness after second thermal cycle at peak temperature 600 ℃ and 1200 ℃. When the peak temperature of the second thermal cycle is 800℃, it forms net microstructure with chain structure in grain boundary and toughness decreases. When the peak temperature of the second thermal cycle is 1000℃, local brittleness with the large M-A islands in granular bainite appears during cooling process.