焊接热输入对P91钢焊接修复微观组织及性能的影响  

Effect of welding heat input on microstructure and properties of P91 steel in welding repair

作　　者：晏嘉陵 齐彦昌[3] 刘明星 常子金 崔冰[3,4] YAN Jialing;QI Yanchang;LIU Mingxing;CHANG Zijin;CUI Bing(East China Electric Power Test&Research Institute,China Datang Corporation Science and Technology Research Institute Co.,Ltd.,Hefei 230088,China;Datang Boiler Pressure Vessel Inspection Center Co.,Ltd.,Hefei 230088,China;Welding Institute,Central Iron and Steel Research Institute,Beijing 100081,China;School of Materials Science and Engineering,Anhui University of Technology,Ma'anshan 243000,China)

机构地区：[1]中国大唐集团科学技术研究总院有限公司华东电力试验研究院,合肥230088 [2]大唐锅炉压力容器检验中心有限公司,合肥230088 [3]钢铁研究总院焊接研究所,北京100081 [4]安徽工业大学材料科学与工程学院,安徽马鞍山243000

出　　处：《材料科学与工艺》2024年第5期74-83,共10页Materials Science and Technology

摘　　要：为进一步揭示补焊热输入对补焊接头焊缝区微观组织与性能的影响规律,本文通过微观组织表征、显微硬度测试、拉伸实验和冲击实验等方法,对比研究了焊接热输入对P91钢焊接接头焊接缺陷、微观组织和力学性能的影响。结果表明,热输入为10kJ/cm时,补焊区焊缝金属中树枝晶呈平行状;热输入增加到15kJ/cm时,补焊区焊缝组织呈现出交叉互锁的燕尾搭接状形态;而热输入进一步增加到20kJ/cm时,补焊区的焊缝组织以平行状树枝晶为主和少量的交叉互锁的燕尾搭接状树枝晶组成。补焊区的析出相主要由NbC、Cr_(23)C6和Fe_(2)Nb(Laves相)组成,且随着热输入的增加,析出相熟化长大。力学性能分析表明,补焊区焊缝金属的强度和冲击韧性随热输入的增加均呈现出先增加后降低的变化趋势。热输入为15kJ/cm时,补焊区焊缝金属的枝晶形态和析出物形态所导致的“协同效应”使得显微裂纹形核、发育、扩展所需的能量阈值有所不同,进而补焊区的焊缝金属可以保持相对较高的韧性,因此热输入为15kJ/cm时,补焊区焊缝组织的强韧匹配最优。而3种热输入下的补焊区的焊接热影响区由于晶粒粗大以及补焊过程中的高拘束应力使得该区域的冲击韧性最差。To further reveal the influence law of heat input in repair welding on the microstructure and properties of the weld zone of the repair welding joint,a comparative study of the influence of heat input in welding on the welding defects,microstructure and mechanical properties of P91 steel welded joint are conducted by microstructure characterization,microhardness test,tensile test and impact test.Results show that when the heat input is 10 kJ/cm,the weld metal microstructure in the repair welding zone are parallel dendrites.When the heat input increase to 15 kJ/cm,the weld metal microstructure in the repair welding zone shows a dovetail lap shape of cross interlocking.When the heat input is further increased to 20 kJ/cm,the weld metal microstructure in the repair zone is mainly composed of parallel dendrites and a few dovetail lap dendrites interlocked.The precipitated phase in the repair welding zoneis mainly composed of NbC,Cr_(23)C_(6) and Fe_(2)Nb(Laves phase),and the precipitated phase grows with the increase of heat input.The mechanical property analysis reveals that the strength and impact toughness of the weld metal in the repair zone increase first and then decrease with the increase of heat input.When the heat input is 15 kJ/cm,the"synergistic effect"caused by the dendrite morphology and precipitate morphology of the weld metal in the repair welding zone make the energy threshold required for the nucleation,development and expansion of the micro-crack different,and then the weld metal in the repair welding zone can maintain relatively high toughness.When the heat input is 15 kJ/cm,the strength and toughness matching of weld structure in the repair welding zone proves to bethe best.However,the impact toughness of the welding heat affected zone under three kinds of heat input is the worst due to the coarse grain size and the high constraint stress in the welding process.

关 键 词：P91钢 补焊 热输入 微观组织 性能 

分 类 号：TG457.11[金属学及工艺—焊接]