去应力退火对X100M管线管组织性能的影响

为了研究610 ℃去应力退火热处理对X100M管线管组织性能的影响，对退火前后X100M管线管分别取样，进行了母材显微组织观察、室温拉伸性能及低温韧性试验，并分析了退火前后低温冲击典型断口的形貌特征。结果表明，退火热处理后X100M管线管母材显微组织中尺寸细小的贝氏体铁素体含量减少，粗大的准多边形铁素体含量增多；X100M管线管的横向和纵向抗拉强度下降约60~70 MPa，延伸率提高2%~3%；退火后低温韧性有所降低，CVN冲击和DWTT断口均出现分离现象。

Effects of Stress Relief Annealing on the Microstructures and Properties of X100M Line pipe

In order to study the effects of stress relief annealing at 610 ℃on the microstructures and mechanical properties of X100M line pipe, sampling respectively on X100M line pipe before and after annealing, it carried out microstructure observation, tensile test at room temperature and low temperature toughness test, and also analyzed the typical low-temperature impact fracture morphology characteristics before and after annealing. The results showed that, in X100M line pipe base metal microstructure, the volume fraction of small size bainite decreased and the volume fraction of quasi-polygonal ferrite increased after annealing. Both the transverse and longitudinal tensile strength decreased about 60~70 MPa, while the elongation increased by 2%~3%. The low temperature toughness decreased, and the fracture separation phenomenon was observed in CNV impact and DWTT fracture.