长时高温时效对T23钢水冷壁焊缝微观组织影响  

Long-term High Temperature Aging on the Microstructure of T23 Water-cooled Wall Welds Influences

作　　者：尹少华 张振华[3] 孙志强[1] 罗震[2] YIN Shaohua;ZHANG Zhenhu;SUN Zhiqiang;LUO Zhen(Suzhou Nuclear Power Research Institute Co.,Ltd.,Suzhou 215004;School of Materials Science and Engineering,Tianjin University,Tianjin 300350;CHN Energy Xuzhou Power Co.,Ltd.,Xuzhou 221166)

机构地区：[1]苏州热工研究院有限公司,苏州215004 [2]天津大学材料科学与工程学院,天津300350 [3]国能徐州发电有限公司,徐州221166

出　　处：《机械工程学报》2024年第12期277-286,共10页Journal of Mechanical Engineering

摘　　要：对T23水冷壁管接头焊缝进行530℃×100 h、530℃×500 h、530℃×1000 h、600℃×100 h、600℃×500 h、600℃×1000 h共6组参数的高温时效试验。对接头焊缝区进行系统研究发现:首先,焊缝区产生再热裂纹主要是由于M23C6型析出物在晶界析出、长大导致晶界形成软化区,同时与M23C6伴生的孔洞进一步减弱了晶间结合力,在应力松弛过程中应变主要集中在晶界;其次,未热处理的焊接接头运行后,焊缝区短期内出现二次硬化,晶内强度与晶界强度差增大,再热裂纹敏感性曾高,导致T23水冷壁接头短期内发生泄漏;第三,焊后热处理使不稳定的焊缝区组织发生预先转变,碳化物大量析出,基体发生回复与再结晶,降低了晶内强度,同时晶界附近合金元素贫化消除,晶内和晶界强度的差异减小,塑性变形能力明显提升,再热裂纹敏感性降低。The high-temperature aging tests of T23 water-cooled pipe joint were carried out with 6 parameters,namely 530 Cx100 h,530℃x500 h,530 Cx1000 h,600 C×100 h,600 C×500 h,600 C×1000 h.A systematic study on the weld zone of the joint shows that:firstly,the reheat crack in the weld zone is mainly caused by the precipitation and growth of M23C6 precipitates at the grain boundary,which leads to the formation of a softening zone at the grain boundary,and the pores associated with M23C further weaken the intergranular bonding force,and the strain is mainly concentrated at the grain boundary during the stress relaxation process;Secondly,after the welded joint without heat treatment was put into service,secondary hardening occurred in the weld zone in a short period of time,the difference between intragranular strength and grain boundary strength increased,and the sensitivity of reheat crack increased,which led to the leakage of T23 water wall joint in a short period of time.Thirdly,the post-weld heat treatment makes the unstable weld zone structure pre-transform,a large number of carbides precipitate,the matrix recovers and recrystallizes,which reduces the intragranular strength.At the same time,the dilution of alloy elements near the grain boundary is eliminated,the difference between intragranular and grain boundary strength is reduced,the plastic deformation ability is obviously improved,and the sensitivity of reheat cracking is reduced.

关 键 词：高温时效 T23钢 水冷壁 焊缝区 再热裂纹 

分 类 号：TG44[金属学及工艺—焊接]