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用金相分析、硬度试验和X射线衍射方法研究了30CrMnSiA钢经亚温淬火后所得α相(铁素体)对渗氮后渗氮层深度、硬度、脆性以及相组成的影响。结果表明,与渗氮前的调质态原始组织相比,由于渗氮前采用了亚温淬火以获得极为细小的两相复合组织,可能提供了氮原子的扩散通道和氮化物的更多形核部位以及由于合金元素含量较低的α相的存在,从而使渗氮后渗氮层中的氮化物(ε、γ′)含量较多;使渗氮层的硬度增加,但并不增加脆性:对渗氮层深度的增加亦有所裨益。渗氮不改变亚温淬火后所得的两相复合组织,因而保留了亚温淬火的强韧化效果。
The effects of α phase (ferrite) after nitriding on the depth, hardness, brittleness and phase composition of nitrided nitrided layer of 30CrMnSiA steel were studied by metallographic analysis, hardness test and X-ray diffraction. The results show that compared with the pre-nitrided virgin green structure, sub-temperature quenching was used before nitriding to obtain the extremely fine two-phase composite structure, which may provide a more polymorphic form for the diffusion channels of nitrogen atoms and nitrides Nitrides (ε, γ ’) content in the nitrided layer after nitriding is relatively high due to the presence of the α-phase and the core parts as well as the α phase having a lower content of alloying elements; the hardness of the nitrided layer is increased but the brittleness is not increased : It is also beneficial to increase the depth of nitrided layer. Nitriding does not change the two-phase composite structure obtained after sub-temperature quenching, thus preserving the strengthening effect of sub-temperature quenching.