不同冲击性能低温容器用9Ni钢的微观研究

发布时间：2019-03-14 14:32

【摘要】：对冲击性能不同的9Ni钢试样从微观方面进行了比对分析,用扫描电子显微镜、金相显微镜、电子探针和扫描电镜电子背散射衍射(EBSD)进行组织、非金属夹杂物、奥氏体晶粒、低倍枝晶和残余奥氏体量的观察研究。研究结果表明:冲击功值低的试样断口呈脆性解理断裂,低倍枝晶形貌图显示柱状晶发达,奥氏体晶粒粗大且不均匀;而冲击功值高的试样断口呈韧性断裂,各晶区可明显区分,奥氏体晶粒细且均匀。两组试样的夹杂物评级没有明显差异,说明两组试样的冲击性能差异是由于不恰当的连铸工艺使得柱状晶过于发达,铸态枝晶间形成富镍的偏析带,镍的偏析带在随后的热加工中不能被完全消除而遗传下来,造成了钢板镍元素的微观偏析,引起了组织不均匀,并降低了9Ni钢的冲击性能。
[Abstract]:The microstructure, non-metallic inclusions and austenite grains of 9Ni steel samples with different impact properties were analyzed by scanning electron microscope (SEM), metallographic microscope (SEM), electron probe (EPMA) and electron backscattering diffraction (EBSD). Observation and study of low-power dendrite and residual austenite. The results show that the fracture surface of the specimen with low impact work value is brittle cleavage fracture, and the low dendrite morphology shows that the columnar grains are developed and the austenite grains are coarse and non-uniform. However, the fracture surface of the specimen with high impact work value is ductile fracture, and the crystal regions can be distinguished obviously. The austenite grains are fine and uniform. There is no significant difference in inclusion rating between the two groups, indicating that the difference in impact properties between the two groups is due to the excessive development of columnar crystals and the formation of Ni-rich segregation bands between as-cast dendrites due to improper continuous casting technology. The segregation band of nickel can not be completely eliminated and inherited in subsequent hot-working, which results in micro-segregation of nickel elements in steel plate, resulting in uneven microstructure, and reduces the impact property of 9Ni steel.
【作者单位】：中国海洋石油总公司采办中心;
【分类号】：TG142.1

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