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研究了激光立体成形技术制备的300M超高强度钢试样热处理前后的组织演化。结果表明,300M钢的沉积态组织呈现细密的初生奥氏体柱状枝晶形态,并导致整体相形态呈现一定的取向性,相组成由底部的马氏体为主经中部的马氏体+下贝氏体转变为顶部的马氏体+上贝氏体。经过热处理后,初生的柱状枝晶生长形态消失,组织明显均匀细化,呈现显著细化的板条状马氏体形态。另外,本文还分析了激光立体成形300M钢可能出现的宏观缺陷,并指出了其成因。
The microstructure evolution of 300M ultra-high strength steel samples prepared by laser three-dimensional forming technology before and after heat treatment was studied. The results show that the microstructure of 300M steel shows a fine columnar dendritic morphology of primary austenite and leads to a certain orientation of the overall phase morphology. The phase composition is mainly composed of the bottom martensite and the middle martensite + Bainite into the top of the martensite + upper bainite. After heat treatment, the morphology of primary columnar dendrites disappeared and the microstructure was obviously and uniformly refined, showing a remarkably refined lath martensite morphology. In addition, this paper also analyzes the macroscopic defects that may appear in the laser stereolithography 300M steel and points out its cause.