显微组织对贝氏体高强度钢冲击性能的影响  

Effect of microstructure on toughness of high strength bainitic steel

作　　者：杜民献[1,2] 王孟君[2] 

机构地区：[1]湖南工业大学冶金工程学院,湖南株洲412007 [2]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《金属热处理》2015年第4期40-44,共5页Heat Treatment of Metals

基　　金：湖南省自然科学基金(14JJ3124)

摘　　要：对比两组冲击吸收能量差别较大的贝氏体高强钢试样,采用光学显微镜、扫描电子显微镜SEM结合电子背散射衍射（ EBSD）分析了显微结构对钢的冲击性能的影响。结果表明,钢基体中存在尺寸在3-6μm的（ Ti,Nb）（ N,C）析出物导致脆断断裂。冲击吸收能量偏低试样在厚度的1/4和1/2处平均有效晶粒尺寸都明显大于冲击吸收能量较高试样,会导致材料的冲击性能降低。同时冲击吸收能量偏低试样的小角度晶界所占比例明显偏高,而在断裂过程中不能有效阻止裂纹扩展,因此也会导致钢的冲击性能降低。Compared with two groups of high strength bainitic steel, which have large difference of impact absorbed energy, the effect of microstructure on impact toughness of the steel was analyzed by use of OM, SEM combined with electron back scattering diffraction （ EBSD） . The results show that Ti, Nb（ N, C） precipitate sized 3-6 μm results in brittle rupture of the steel. The average effective grain size in 1/4 and 1/2 thickness of the steel sample with low impact absorbed energy is obvious larger than the grain size of the sample with high impact absorbed energy, such lead to reduce of impact toughness. Meanwhile, the small angle grain boundaries of the steel sample with lower impact absorbed energy are seazed of obvious higher portion and it could not effectively prevent crack propagating, so the impact toughness reducing could be occur too.

关 键 词：高强贝氏体钢 冲击性能 有效晶粒尺寸 小角度晶界 

分 类 号：TG115[金属学及工艺—物理冶金]