X80管线钢焊接二次热循环粗晶区的韧性和显微组织研究

Microstructure and Toughness of Coarse Grained Region in X80 Pipeline Steel During Double Welding Thermal Cycle

利用热模拟技术,采用光学、透射电镜和冲击韧度、裂纹尖端张开位移(CTOD)试验研究了X80管线钢在(多道焊接)二次热循环过程中粗晶区的韧性与显微组织的关系。结果表明:当二次峰值温度处于(α+γ)两相区温度范围时,再热粗晶区的韧性最低,具有明显的临界粗晶区局部脆化倾向,引起临界粗晶区局部脆化的主要原因是形成了粗大的岛状组织。

The relationship between microstructure and toughness of coarse grained region in X80 pipeline steel during double welding thermal cycle was investigated using welding thermal simulation technique, OM and TEM as well as impact toughness and crack tip opening displacement （CTOD） tests. The toughness of reheated coarse grained region, which was characteristic of critical coarse grained region, was the lowest as the second peak temperature was in two phase（α＋γ）temperature range. The local brittlement in critical coarse grained region was caused mostly by island structure.