铸态30CrMnSiNi2A钢的热变形行为与热加工图

Hot Deformation Behavior and Hot Processing Map for As-cast 30CrMnSiNi2A Steel

目的研究铸态30CrMnSiNi2A钢的热变形行为,并建立热加工图评估出合适的热变形参数。方法在变形温度900~1200℃和应变速率0.01~10 s^(−1)条件下开展热压缩实验,分别构建应变0.2、0.4、0.6、0.8下的热加工图,结合扫描电镜对变形后的微观组织进行分析。结果30CrMnSiNi2A钢在压缩过程中真应力的变化是加工硬化和动态软化协同作用的结果;在低应变速率时(0.01、0.1 s^(−1)),流动曲线在应力值达到峰值应力(σp)后都表现出流动软化现象,而在高应变速率下流动曲线则表现出连续的加工硬化现象。结论根据变形试样的微观组织和塑性流动是否稳定,可将热加工图分为3个区:流动失稳区、不完全动态再结晶区、完全动态再结晶区,在完全动态再结晶区内的晶粒细小均匀,所以将变形温度1100~1180℃、应变速率0.01~0.5 s^(−1)确定为适合于30CrMnSiNi2A钢的加工窗口。

The work aims to investigate the deformation behavior of as-cast 30CrMnSiNi2A steel and establish the hot processing map to evaluate the appropriate thermal deformation parameters.Thermal compression experiment was carried out on as-cast 30CrMnSiNi2A steel at deformation temperature range of 900-1200℃and the strain rate range of 0.01-10 s^(−1).The hot processing map under the strain of 0.2,0.4,0.6 and 0.8 was constructed,respectively,and the microstructure after deformation was analyzed by scanning electron microscope.It was found that the change of flow stress of 30CrMnSiNi2A steel was affected by processing hardening and dynamic softening.At low strain rates(0.01,0.1 s^(−1)),the flow curves showed flow softening after the stress values reached the peak stress(σp),while the flow curves showed continuous work hardening at high strain rates.In terms of microstructure of the deformed samples and whether plastic flow is stable or not,the processing map can be divided into three areas:instability zone,incomplete dynamic recrystallization zone,and complete dynamic recrystallization zone.The grains are fine and uniform in the complete dynamic recrystallization zone,so the temperature of 1100-1180℃and the strain rate of 0.01-0.5 s^(−1) are determined to be suitable processing window for the as-cast 30CrMnSiNi2A steel.