基于应变设计的X70钢管软化及脆化研究

Study on the Softening and Embrittlement of Strain-based Design X70 Steel Pipe

为了研究基于应变设计的X70钢管在焊接热循环作用下热影响区软化和脆化现象,采用焊接热模拟试验、系列温度冲击试验及硬度检测等方法,分析了焊接接头热影响区组织形成、低温冲击韧性和软化程度大小的影响因素。研究结果表明,X70大变形钢焊接热影响区的脆化现象不明显,但存在不同程度的软化现象,填充层硬度最大降低10%,盖面层硬度最大降低11.6%。通过对焊缝的补强覆盖焊接增大了焊缝余高的宽度和高度,解决了焊缝热影响区的软化的问题。

In order to find the reason of softening and embrittlement of strain-based design X70 steel pipe, using the methods of welding thermal simulation test, series temperature impact test, hardness measurement and so on, it analyzed the heat affected zone microstructure formation of welded joint, low temperature impact toughness and the influence factors of softening degree. The research results indicated that the embrittlement of the thermal influence zone of X70 large deformation steel welding heat affected zone was not obvious, but existed different degrees softening phenomenon, the hardness of the filling layer was reduced by 10%, and the hardness of the cover layer decreased by 11.6%. The width and height of welds were increased by the welding of weld reinforcement, which solved the softening problem of weld heat affected area.