B+M/A复相组织X80大变形管线钢的预应变脆化

Embrittlement of a B+M/A Dual Phase X80 Pipeline Steel with Large Deformation during Pre-strain

采用热模拟试验机对X80管线钢进行了在线加热配分(HOP)处理,随后对HOP处理后的管线钢(HOP钢)进行了不同应变量下的预拉伸变形,研究了预拉伸应变量对该钢显微组织和力学性能的影响,分析了其预应变脆化现象。结果表明:HOP钢的显微组织由贝氏体+马氏体/奥氏体(B+M/A)组成,当预应变量为4%时,贝氏体形成了明显的胞状亚结构且较大预应变量下的胞状亚结构数量较多、尺寸较小;随着预应变量的增加,HOP钢的拉伸强度和硬度基本呈增大的变化趋势,而塑性呈减小的变化趋势,该钢发生了明显的脆化。

The heating on-line partitioning （HOP）treatment was conducted on the X80 pipeline steel by a thermal simulator,and then the HOP treated pipeline steel （HOP steel）was pre-stretching deformed at the different stains.The effects of the pre-stretching strain on the microstructure and mechanical properties of the steel were investigated and the pre-strain embrittlement phenomenon was analyzed.The results show that the microstructure of the HOP steel was composed of bainite and martensite/austenite （B＋M/A）.The obvious cellular substructure of the bainite was formed at the pre-strain of 4%,and the amount of the cellular substructures was relatively large and the size was relatively small at a relatively high pre-stain.With the increase of pre-strain,the tensile strength and hardness of the HOP steel showed an increasing trend while the plasticity and impact energy a decreasing trend,indicating an obvious embrittlement of the steel.