3.5Ni低温钢中Mn元素的强韧性作用研究

Toughening effect of Mn in 3.5Ni low temperature steel

利用光学显微镜和电子探针对不同Mn含量3.5Ni低温钢的显微组织进行观察和分析,并研究了Mn元素对钢板热轧态、正火态及正火+回火态显微组织和力学性能的影响。结果表明,Mn含量的变化不影响组织的类型及晶粒的大小,提高低温钢中Mn元素含量可增加置换原子Mn的比例,增强低温钢的强度,但其带状组织更为明显;降低3.5Ni低温钢中Mn含量可使带状组织减少,有利于其低温韧性的提高;正火工艺能够有效地均化、细化钢板的显微组织,改善钢板的冲击韧性,且可明显降低材料韧脆转变温度。

The microstructure of 3.5Ni low temperature steel with different contents of Mn was studied by using OM and TEM. The effect of Mn on the microstrueture and mechanical properties of steel plate in rolling state, normalizing state and tempering state was investigated. The results show that the change in Mn content does not influence structural type and grain size. The increase in Mn content can increase the proportion of substitutional atoms and improve the mechanical strength of the steel, but the banded structure is more serious. The decrease in Mn content can reduce the banded structure and be beneficial to the toughness of the steel. The normalizing process can effectively uniform and re- fine grain sizes of the plate, and simultaneously raise the impact toughness and reduce the ductile brit- tle transition temperature significantly.