P91钢焊缝金属碳化物聚集程度的差异对焊缝金属冲击韧性的影响  

Effect of Different Degree of Carbide Aggregation in P91 Steel Weld Metal on the Impact Toughness of Weld Metal

作　　者：李文清 马景平 曹睿[1,2] 徐晓龙[3] 杨飞[3] 毛兴贵[3] 蒋勇[3] 闫英杰[1,2] LI Wenqing;MA Jingping;CAO Rui;XU Xiaolong;YANG Fei;MAO Xinggui;JIANG Yong;YAN Yingjie(The State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Atlantic China Welding Consumables,INC,Zigong 643000,Sichuan,China)

机构地区：[1]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,兰州730050 [2]兰州理工大学材料科学与工程学院,兰州730050 [3]四川大西洋焊接材料股份有限公司,四川自贡643000

出　　处：《材料导报》2024年第20期198-204,共7页Materials Reports

基　　金：国家自然科学基金(52175325,51961024,52071170);甘肃省科技重大专项(22ZD6GA008)。

摘　　要：利用夏比冲击试验、SEM扫描电镜和EBSD分析等方法研究了在P91钢焊缝金属微观组织中晶界处碳化物的聚集程度差异对焊缝金属冲击韧性的影响。结果表明:焊态与热处理态下P91钢焊缝金属微观组织不同,焊态下组织为未回火板条马氏体组织,热处理态为铁素体组织。碳化物沿着晶界呈颗粒链的形式聚集,在碳化物周围观察到了微孔及微孔聚集的现象。碳化物颗粒在力的作用下发生应力集中,在碳化物周围形成微孔,晶界处碳化物颗粒链聚集程度越高,则微孔体积分数越高,微孔快速聚集到一起形成裂纹,导致冲击韧性降低。基体中析出相呈弥散分布,析出相数量越多,基体弥散强化效果越显著,冲击韧性降低。EBSD实验结果表明,晶界处分布着大量M_(23)C_(6)型碳化物,基体中也有少量的M_(23)C_(6)型碳化物。The impact toughness of P91 weld metal was studied by using impact testing,SEM and EBSD testing to investigate the effect of different degrees of carbide aggregation at grain boundaries in the microstructure of the weld metal.The results indicate that the microstructure of as welded state is different from that of heat treated state.The microstructure of as welded state is untempered flat noodles martensite,while that of heat treated state is ferrite.Carbides aggregate in the form of particle chains along grain boundaries,and the phenomenon of micropores and their aggregation around the carbides has been observed.Under the action of force,carbide particles undergo stress concentration,forming micropores around the carbide.The higher the degree of aggregation of carbide particle chains at grain boundaries,the higher the volume fraction of micropores,and the rapid aggregation of micropores to form cracks,resulting in a decrease in impact toughness.The precipitates in the matrix exhibit a dispersed distribution,and the more precipitates there are,the more significant the dispersion strengthening effect of the matrix is,and the impact toughness decreases.The EBSD results indicate that a large amount of M_(23)C_(6)type carbides are distributed at the grain boundaries,and there is also a small amount of M_(23)C_(6)type carbides in the matrix.

关 键 词：P91耐热钢 冲击韧性 碳化物 

分 类 号：TG441[金属学及工艺—焊接]