H13钢低温化学热处理渗层热疲劳特性研究

Study on the Thermal Fatigue Properties of Diffusion Layer on Steel H13 Treated with low Temperature Thermochemical Treatment

通过对H13钢低温化学热处理表面强化后热疲劳性能的研究,探讨了表面强化渗层在不同热循环温度和外加拉应力下热疲劳裂纹萌生、扩展及分布状态的规律.研究结果表明,在低循环温度下,表面强化可通过阻止疲劳裂纹萌生和降低裂纹扩展速率来提高热疲劳性能;在高循环温度下,表面强化只能通过阻止疲劳裂纹向纵深扩展速度和降低裂纹密度来提高热疲劳性能.当外加拉应力较低时,表面强化可以有效地提高热疲劳性能.

Based on the study on the thermal fatigue properties of diffusion layer on steel H_(13) treated with low temperature thermochemical treatment,the laws of thermal fatigue cracks of initiation,propagation and distribution in different test cycling temper- ature and stress has been discussed.The results show that in the condition at lower cycling temperature,the thermal fatigue properties of hardened surface layer can be increased by preventing from the initiation of crack,reducing propagation rate of cracks.At the higher cycling temperature,thermal fatigue properties can only be improved by preventing from the development of cracks in deep direction and decreasing the density of cracks.When the applied tensile stress is lower,the thermal fatigue property can be enhanced effectively by surface strengthening.