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一、引言用Cr12钢(Cr12,Cr12MoV)制造的模具,一般淬火时是冷至室温。然而其马氏体转变终了点M_f大约在-70～-80℃左右(图1),因而室温下的残留奥氏体(A_R)量多,易导致模具的变形和磨裂,降低模具的硬度、强度、耐磨性、铁磁性及回火稳定性。根据冷处理原理,如果将淬火后的模具在回火前继续冷至M_f点,那么大部分A_R将转变为马氏体,可改善性能,提高质量,延长使用寿命。
First, the introduction Cr12 steel (Cr12, Cr12MoV) to create the mold, the general quenching is cold to room temperature. However, its martensitic transformation end point M_f is about -70 ~ -80 ℃ (Figure 1), so the amount of residual austenite (A_R) at room temperature and more easily lead to mold deformation and grinding, reducing the hardness of the mold , Strength, wear resistance, ferromagnetism and tempering stability. According to the principle of cold treatment, if the mold after quenching continue to be cooled to M_f before tempering, most A_R will be transformed into martensite to improve performance, improve quality and prolong service life.