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通过热模拟技术与显微分析方法研究了二次热循环对X100管线钢粗晶热影响区组织的影响规律,再热粗晶区的性能通过夏比V型缺口冲击试验表征。试验结果表明,当二次热循环的峰值温度处于(α+γ)两相温区,试验钢的临界粗晶热影响区出现局部脆化。局部脆化的原因主要有两个:一是临界粗晶热影响区组织粗化;另一是该区MA组元数量多,尺寸大,硬度高。
The effects of secondary thermal cycling on the microstructure of the heat affected zone (HAZ) of X100 pipeline steel were studied by means of thermal simulation and microscopic analysis. The properties of the reheated coarse-grained zone were characterized by Charpy V-notch impact test. The experimental results show that when the peak temperature of the second thermal cycle is in the (α + γ) two-phase temperature zone, the local brittleness occurs in the critical coarse heat affected zone of the test steel. There are two main reasons for local embrittlement: one is the coarsening of the coarse-grained heat-affected zone; the other is the large number of MA elements in the area with large size and high hardness.