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本文应用电镜薄膜技术,观察30CrMnSiNi A超强度钢在回火过程中,马氏体转变的精细结构,说明低温回火的断裂韧性大小,决定于马氏体分解的析出相的性质、形态以及它与基体相的共格关系。高温回火断裂韧性的升高,主要是由于Fe_3C的球化与细小的合金碳化物在晶介上的富集,形成一个薄膜而韧化晶介的结果。高温回火脆性区在550℃左右,此时晶介富集了片状M_(23)C_6化合物形成脆性界面。回火温度进一步提高,M_(23)C)6化合物球化,基体回复,形成索氏体组织,断裂韧性再次上升。
In this paper, the fine structure of martensite transformation of 30CrMnSiNi A super-strength steel during tempering was observed by means of electron microscopy. The fracture toughness of the low temperature tempering depends on the nature and morphology of precipitated phase of martensite decomposition Coherent relationship with the matrix phase. The increase of tempering fracture toughness at high temperature is mainly attributed to the Fe3C spheroidization and the small alloy carbides enriching on the crystal, forming a thin film and toughening the crystal structure. The high temperature temper brittle zone is about 550 ℃. At this point, the mesogen enriches the flaky M_ (23) C_6 compound to form brittle interface. The tempering temperature was further increased. The M_ (23) C) 6 compounds were spheroidized, the matrix was recovered and sorbite was formed, and the fracture toughness increased again.