Ni元素对Cr-Ni-Mo系高强焊缝组织演化的影响
Effect of Ni on the microstructure evolution of Cr-Ni-Mo series high strength weld metal
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摘要: 主要利用金相显微镜(OM)、高分辨热场扫描电镜(FEGSEM)附带能谱仪(EDX)、透射电镜(TEM)等手段对不同Ni元素含量的高强钢焊缝组织及成分进行了观察分析,阐明了焊缝成分对组织的影响.利用Thermol-Calc热力学软件对两种焊缝的凝固模式进行了探讨.结果表明,随着Ni元素含量的提高,高强钢焊缝由板条贝氏体和马氏体为主的组织变为板条更细小的马氏体与粗大联合贝氏体的混合组织,而且焊缝硬度大大提高.Ni元素含量的增加提高了焊缝强度,并保持了良好的低温韧性.Ni元素含量的提高改变了焊缝的凝固模式,直接由液态转变为奥氏体,造成合金元素Mn和Ni在枝晶间偏析.Abstract: The microstructure of the weld metal with different Ni contents was characterized and analyzed by using OM, FEGSEM equipped with EDX and TEM. The solidification mode was also discussed by Thermol-Calc software. The results show that with the increase of the Ni content, the microstructure mainly composed of lath bainite and lath martensite became the mixture of martensite and coalesced bainite. With the increase of the Ni content, the strength of weld metal increased and the low temperature toughness of weld metal was good. The weld metal with higher Ni content solidified completely as austenite, causing dendritic segregation of Mn and Ni.