WCX355超细晶粒钢晶粒长大规律的热模拟实验研究

Grain growth in coarse-grained zone of WCX355 ultrafine grained steel under thermal simulation

利用Gleeble-3500热模拟实验机,对汽车用WCX355超细晶粒钢板进行热模拟实验,通过观察实验材料的显微结构,找出了其晶粒的长大规律。发现:当保持实验控冷时间t8/5=5s时,粗晶区晶粒在加热温度大于1200℃后发生明显长大;而当固定加热峰值温度Tp=1350℃时,随着控冷时间的增大,超细晶粒钢晶粒尺寸线性增大。实验前后材料未发生明显的硬化或软化。

Objective Thermal simulation testing was carried out on WCX355 ultrafine grained steel by using Gleeble-3500 machine. The microstructure of samples was examined to study the tendency of grain growth. The results show that dramatic grain-growth happened if the heating peak temperatures （Tp） was over 1 200℃ while the cooling condition was fixed by t8/5=5 s. On the other hand, when Tp was kept at 1 350℃, the average grain size of ultrafine grained steel proportionally increased with the increasing of cooling time. The hardness of coarse-grained zone of WCX355 ultrafine grained steel tested by thermal simulation was slightly changed alone with the changing test parameters. However, no distinct hardening or softening effect was found for coarse grains.