Cr12MoV钢陶瓷模具异常开裂分析

Failure Analysis of Abnormal Cracking on Ceramic Die of Cr12MoV Steel

Ｃｒ１２ＭｏＶ钢制陶瓷模具正常失效方式为磨损。一批上模早期开裂失效的主要原因是回火不足，导致残存的淬火组织应力与热应力在后续磨削和线切割加工中产生机械应力叠加后超过材料强度所致。改锻和球化退火不充分，使Ｃｒ１２ＭｏＶ钢共晶碳化物呈带状、网状分布且颗粒粗大而带尖角并促进了裂纹的发展。模具结构中尖角及其间的棱边因应力集中而成为众多宏观裂纹的起点和纵深发展地带。经补充回火的模块在后续磨削和线切割成形中未发现微裂纹，从而在生产应用中以磨损方式正常失效。

The wear is taken as normal failure in the ceramic die of Cr12MoV steel.Early cracking of the top die is due to lacking in tempering,which causes the residual structure stress and thermal stress and additional mechanical stress during grinding and linear cutting beyond the materials strength.When the forging and spheroidizing annealing are insufficient,the eutectic carbides of the steel bring about network and banded distribution and accelerate development of the cracks.The wedge angle and edge stress concentration in the die become starting point and zone developed in depth for the macrocracks After additional tempering ,any microcracks on the dies are not found during grinding and linear cutting.