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根据失效分析,认为Cr12钢制针模具早期破损的原因是组织中的块状共晶碳化物和带状碳化物偏析;采用强韧化工艺,可改善碳化物的形状、大小和分布,得到卵形共晶碳化物和细小弥散的二次碳化物,减少裂纹产生的可能。试验表明:经强韧化处理,Cr12钢的断裂韧性值比常规淬火的高,模具寿命可提高一倍以上。三点弯曲结合声发射检测可提供钢在断裂过程的动态信息。经强韧化处理的Cr12钢在断裂前,裂纹产生及扩展形成较强的声发射源,在振铃计数率-挠度曲线上呈现幅度较高的不连续峰值。
According to the failure analysis, the reason for the early damage of Cr12 steel needle mold is that the massive eutectic carbides and banded carbides segregate in the structure. The toughening process can improve the shape, size and distribution of carbides to obtain the eggs Shape eutectic carbides and fine secondary carbides to reduce the possibility of cracks. Tests show that: after toughening treatment, the fracture toughness value of Cr12 steel is higher than that of conventional quenching, and the die life can be more than doubled. Three-point bending combined with acoustic emission detection provides dynamic information on the steel during fracture. The strengthened and toughened Cr12 steel forms and develops strong acoustic emission sources before fracture, and shows a discontinuous peak with high amplitude on the ring counting rate-deflection curve.