4Cr5MoSiV1钢和3Cr2W8V钢热疲劳寿命的研究

STUDY ON THERMAL FATIGUE LIFE OF 4Cr5MoSiV1 AND 3Cr2W8V STEELS

从工程角度定义了热作模具钢的热疲劳裂纹起始(TFCI)寿命,并根据修正的Manson-Coffin公式以及热应力引起的应变范围,导出了一个描述TFCI寿命的表达式:N_i=K(△T—△T_0)^(-2)。当热作模具热循环温度差(△T)低于热疲劳损伤的临界温度差(△T_0)时,即△T<△T_0时,热作模具的TFCI寿命趋于无穷。在最佳热处理条件下,4Cr5MoSiVl钢的△T_0为476℃,3Cr2W8V钢的△T_0为416℃。试验结果表明,4Cr5MoSiVl钢比3Cr2W8V钢具有较好的热疲劳抗力。

In this paper the thermal fatigue crack initial (TFCI) life has been defined from view point of engineering. According to the modified Manson-Coffin formula and the strain caused by thermal stress, a new expression to describe the TECI life has been derived: N_i=K(ΔT—ΔT_0)^(-2). When the temperature difference ΔT of cycles is less than the critical temperature difference ΔT_0 causing thermal fatigue damage of hot-working die, i.e. ΔT<ΔT_0, the TFCI life of hot-working die tends to infinity. After optimum heat treatment, the critical temperature difference ΔT_0 of 4CrSMoSiV1 steel is 476℃, and ΔT_0 of 3Cr2W8V steel is 416℃. The test results show that 4CrSMoSiV1 steel has better thermal fatigue resistance than 3Cr2W8V steel.