镀层对模具材料热疲劳性能的影响

Coating Layer on Thermal Shock for Die Material

研究了3Cr2W8V钢基体上的气相沉积TiN、Ti(C,N)和化学镀Ni-P等膜基体系的热疲劳性能,并与40CrNiMo钢上沉积Ti(C,N)对比,着重探讨热应力和高温氧化这两个因素在热作模具材料热疲劳中的作用。气相沉积层抗氧化性能好且有一定的结合牢度,可明显改善基体的热疲劳抗力。Ni-P镀层多在热应力下开裂失去保护作用,不能改善热疲劳性能。结果表明:热作模具的失效中氧化和热应力均可成为主导因素,并随着条件而发生转化。

Thermal shock behavior for vapor deposited TiN and Ti (C, N) and electroless plated Ni-P on 3O2W8V die steel were studied, the results were compared with Ti (C, N) deposited on 40CrNiMo steel. This study was emphasised on the effects of thermal stress and oxidation on thermal shock. Good anti-oxidation aspect with appreciable bonding strength of the vapor deposited layer results in a remarkable improvement of anti-thermal shock behavior. Electroless platied Ni-P layer will crack due to thermal stress, and shows little effect on thermal shock. This experiment leads to a conclusion that either thermal stress or oxidation can be a major factor bringing about premature failure of a hot die, yet the predominant factor could change from one to another depending on the working conditions.