工程机械用低碳贝氏体钢Q550的性能与组织分析

Analysis on Mechanical Property and Microstructure of Low Carbon Bainite Steel Q550 for Engineering Machinery Use

介绍了韶钢的Q550高强度工程机械用钢的生产情况,采用低碳,Nb、V、Ti、Mo等微合金化的成分设计,结合控轧控冷、离线回火工艺生产了厚度达到30 mm的Q550钢板,钢板的力学性能满足交货需要。利用光学显微镜、扫描电镜分析了钢板的组织情况,并使用透射电镜结合能谱仪分析了钢板的析出相情况,分析结果表明Q550钢板的回火组织为粒状贝氏体、针状铁素体以及少量多边形铁素体,晶粒细小、均匀,析出相主要是Nb、Ti的碳氮化物,V、Cr对Q550的析出强化没有贡献。

The production machinery use in Shaogang of the high strength steel plate Q550 with thickness of 30 mm for engineering is introduced. Using low carbon and microalloyed elements such as Nb, V, Ti, Mo etc. plus TMCP and off-line tempering process, the plate was produced with mechanical properties satisfying the delivery requirements. In addition, the microstmcture of the plate is examined by OM, SEM and the precipitated phase analysis by TEM and EDS. The results indicate that the tempered Q550 plate exhibited a microstructure of granular bainite, acicular ferrite and a small amount of polygonal ferrite with fine and uniform grain; The major precipitated phases were carbonitrides of Nb and Ti while V and Cr contribute little to the precipitation strengthening of Q550 plate.