厚规格X80管线钢焊接接头微观组织及力学性能研究

Study of Microstructure and Mechanical Properties of the Welded Joint of Thick X80 Pipeline Steel

利用光学显微镜、扫描电镜和拉伸试验机研究了30.8 mm厚度规格多相组织X80管线钢管体和焊接接头的微观组织和力学性能。结果表明,厚规格X80管线钢管体、焊缝、热影响区具有优异的强韧性。內焊表面位置MA岛尺寸和体积分数均小于外焊。临界粗晶区MA岛在原奥氏体晶界呈链状分布,且临界粗晶区硬度明显高于粗晶区其他位置,但宽度较小,对焊接接头性能危害较小。

The microstructure and mechanical properties of the base metal and welded joint of the multi-phase X80 pipeline steel with 30.8 mm thickness were assessed by means of tensile machine,as well as optical microscopy(OM)and scan electron microscopy(SEM).The results show that the base,weld metal(WM)and heat affected zones(HAZ)have excellent strength and toughness.Under the influence of outside weld thermal cycle,the size and volume fraction of MA constituent at inside welding are smaller than that of outside welding.The presence of necklace-type MA constituent was found along prior austenite grain boundaries at intercritically reheated coarse grain heat affected zone(ICCGHAZ),and the hardness is obviously higher than the regions of reheated coarse grain heat affected zone.However,the width of ICCGHAZ is small,then the risk of embrittlement to the whole weld joint is less.