新型Cr-Mo-V热冲压模具钢的热导率和回火稳定性

Thermal conductivity and tempering stability of a novel Cr-Mo-V hot stamping die steel

以H13钢为参照,采用激光热导仪,扫描电镜和透射电镜等研究了新型热冲压模具Cr-Mo-V钢(GYCM)的热导率和回火稳定性。结果表明,经1030℃奥氏体化30 min油淬后,GYCM钢在600℃保温2 h回火2次和H13钢在580℃保温2 h回火2次后的硬度均约为50 HRC。相同试验条件下,同硬度GYCM钢和H13钢的热导率随温度的变化趋势不同,GYCM钢的热导率随温度升高而降低,而H13钢的热导率随温度升高而升高,且在100~500℃温度范围内,GYCM钢的热导率均高于H13钢,高出20.42%~36.63%。在600、650℃试验温度下,GYCM钢回火后析出大量的尺寸稳定的纳米级Mo和V碳化物,在较高的温度和较长的时间内粗化程度较低,有效降低回火马氏体的软化程度,因此,GYCM钢比H13钢具有更高的回火稳定性。

Thermal conductivity and tempering stability of a new Cr-Mo-V alloyed hot stamping die steel(GYCM) were studied and compared with H13 steel by means of laser thermal conductivity instrument,scanning electron microscope and transmission electron microscope.The results show that after austenitizing at 1030 ℃ for 30 min and oil quenching,the hardness of both the GYCM steel double tempered at 600 ℃ for 2 h and the H13 steel double tempered at 580 ℃ for 2 h are about 50 HRC.Under the same test conditions and with the same hardness,the thermal conductivity of GYCM steel and the H13 steel varies with temperature in different trends.With increase of temperature,the thermal conductivity of GYCM steel decreases,while that of the H13 steel increases.The thermal conductivity of GYCM steel is 20.42%-36.63% higher than that of the H13 steel in the temperature range of 100-500 ℃.When tempered at 600 ℃ and 650 ℃,a large number of size-stable nanoscale Mo and V carbides are precipitated from the GYCM steel,the coarsening degree is lower at higher temperature and for longer time,which effectively reduces the softening degree of tempered martensite.Therefore,the GYCM steel has higher tempering stability than the H13 steel.