52CrNiMoVSi热作模具开裂原因分析

Cracking Analysis of 52CrNiMoVSi Hot Work Die

52CrNiMoVSi热作模具进行热模锻运作时发生开裂,开裂处位于工作面底部。对开裂件进行切割取样,通过宏微观断口观察、金相观察、硬度测试、能谱分析等方法,分析讨论开裂原因。结果表明:52CrNiMoVSi热作模具为疲劳断裂;材料组织含有较多的非金属夹杂物,纯净度较低,成分及组织不均匀导致硬度不均匀,降低材料疲劳强度;在模具持续工作中,型腔圆角半径过小引起较大应力集中,进而导致裂纹萌生和扩展,最终导致开裂,使其寿命远远低于正常件寿命。

52 CrNiMoVSi hot-working die cracked abnormally during hot-forging operation, and the cracking is located at the bottom of the working surface. The cracking parts are cut and sampled, and the causes of cracking are analyzed and discussed through macroscopic and microscopic observation of the fracture, metallographic observation, hardness test, and energy spectrum analysis. The results show that the 52 CrNiMoVSi hot-working die cracked in the form of fatigue fracture. Because the matrix contains many non-metallic inclusions, the purity is low, the composition and structure are not uniform, resulting in uneven hardness and reducing the fatigue strength of the material. In the continuous working of the mold, the radius of the cavity fillet of the hot work die is too small to cause large stress concentration, which leads to crack initiation and propagation, and eventually leads to abnormal cracking, which makes its life much lower than the life of normal parts.