Nb、V微合金钢筋高温热塑性及奥氏体长大规律

High temperature thermoplasticity and austenite grain growth behavior of Nb and V microalloyed steel rebar

在实验室采用Gleeble 3500与箱式电阻炉分别对试验钢的高温热塑性及奥氏体晶粒长大规律进行了测试,研究了Nb对V微合金化高强钢筋高温热塑性与奥氏体长大规律的影响。结果表明：Nb的加入使V微合金化高强度钢筋的高温低塑性区扩大至1035℃,并使800~1000℃范围内的塑性减小,但对650℃以下的塑性有所改善。奥氏体平均晶粒尺寸变化曲线表明,与保温时间相比,加热温度对晶粒尺寸的影响更大;不含Nb试验钢奥氏体晶粒异常长大的温度为1050℃,含Nb试验钢奥氏体晶粒异常长大的温度为1100℃;当加热温度≥1050℃时,含Nb试验钢的晶粒尺寸比不含Nb试验钢细小,减小20μm左右。

High temperature thermoplasticity and austenite grain growth behavior of the tested steels were investigated using the Gleeble 3500 thermo-mechanical simulator and the box type resistance furnace respectively in laboratory, the influence of Nb on the high temperature thermoplasticity and austenite grain growth behavior of V microalloyed high strength steel rebar were studied. The results show that the addition of Nb make the low thermoplasticity area of the high strength steel rebar expand to 1035 ℃ , and the plasticity decrease in the range of 800-1000 ℃, but the plasticity of the steel below 650 ℃ is improved. The average grain size change curve shows that the effect of heating temperature on grain size is greater than that of the holding time. The abnormal grain growth of the tested steel without Nb can be observed at 1050 ℃, but the temperature of austenite abnormal grain growth of tested steel with Nb is 1100 ℃. At even higher temperature than 1050℃, the grain size of the tested steel with Nb is smaller than that of the tested steel without Nb, and reduces by about 20 μm.