Cr12钢模具开裂原因分析

Cr12钢模具在制作过程中出现裂纹。采用光学显微镜、电子显微镜、化学成分分析和硬度测试等方法，对模具材料进行了检测和分析。原材料冶金质量差(碳化物呈网状分布且晶粒粗大)，在随后的锻造过程中又未能改变碳化物分布和形态，导致材料性能差。模具在第一次线切割后未产生裂纹，表明模具经第一次线切割后，材料所受到的各种应力未能达到临界应力值，但此时模具内原有的应力平衡已被破坏，使局部应力的释放并重新分布，尤其向块状粗长的碳化物集中。模具在进行第二次线切割时表面产生的附加拉应力与材料已存在的内应力相叠加，其总应力超过了材料的抗拉强度，导致裂纹沿碳化物脆性开裂。

CRACKING ANALYSIS OF Cr12 STEEL DIE

Crack of Cr12 steel die was discovered on the making process. By means of the SEM, metallographical examination, chemical analysis and hardness measurement, die cracking was analyzed. The result showed that the quality of original material is not good (the reticulation carbides and big grain carbides ), and defects are occured during forging of die, these factors cause the performance of the material is not good. The reticulation carbides and big grain carbides in the die caused the stress concentrition. The internal stress in the die and the surface stress produced on line incision are combined. The resultant stress will exceed the tensile strength of the material, and caused the brittle cracking.