X80钢焊缝再热后的组织与性能

Microtructure and Performance on Weld of Reheated X80 Steel

针对西气东输二线X80高强度高韧性厚壁管线钢管双面埋弧焊接工艺特点,采用Gleeble1500热模拟试验和实物焊接试验,研究分析了内焊缝(一次焊缝)受到外焊(二次焊接)热循环后组织与性能变化情况。通过SEM、光学显微镜等进行了微观组织分析并做力学性能测试。结果表明,一次焊缝受到二次焊接热循环峰值温度在(α+γ)两相区范围时发生脆化,韧性降低22%;而一次焊缝在外焊二次热输入为20 kJ/cm时,冲击韧性最好;二次焊接在一次焊缝中形成了焊接临界粗晶区(WICHAZ),呈现粗大的条状铁素体,板条间为排列成行M-A组元或渗碳体,硬度由212HV5迅速增加到261HV5,韧性也随之变差。

According to process features of the double-sided Submerged arc welding of the heavy walled Grade X80 line pipe with high strength and high-ductility of Second West to East Gas Pipeline project,using the thermal simulation experiment on Gleeble-1500 thermal simulator and physical welding experiments,change of structure and performance of inside weld（primary weld） reheat by outside weld（secondary weld） was analyzed.Through microstructure analysis by means of SEM,optical microscope and mechanical property test,the results show that inside weld begins embrittlement at two phase region（α＋γ） peak temperature influenced by secondary weld thermal cycle,22% ductility reduced;and impact toughness of primary weld is best when heat input of the secondary weld is 20kJ/cm.M-A constituent or cementite arrange in a row in the intercrystalline of the coarse bar ferrite in WICHAZ of primary weld produce by secondary weld,the hardness increases rapidly from 212HV5 to 261HV5 in this area,and toughness turns bad.