核电SA508-3钢在不同冷速下的显微组织

Microstructure of SA508-3 steel for nuclear power under different cooling rates

针对由某公司生产首次应用到核电上的SA508-3钢,采用膨胀法在Gleeble1500D热模拟机上测定了其焊接连续冷却转变的膨胀曲线,结合显微组织和硬度,获得了每个冷速下对应的相变点温度.结果表明,在0.015~0.05℃/s冷速范围内,为高温转变的铁素体和珠光体区,0.1~7℃/s冷速范围内,为中温转变的贝氏体区,20~80℃/s的冷速范围内,为低温转变的马氏体区;随着冷却速度的增大,硬度值也越来越大,0.015℃/s对应的硬度值为199 HV,80℃/s对应的硬度值为546 HV,这为制定合理的焊接工艺提供了依据.

The new test material was SA508-3 steel used for nuclear power,produced by the China First Heavy Industries Co.,Ltd.The as-received material was subjected to obtaining the dilatation curves in continuous cooling by dilatation method on Gleeble-1500D thermal simulation testing machine,combined with microstructure analysis and hardness test to get SH-CCT curves.It was found that there is high temperature ferrite and pearlite transition region under cooling rate of 0.025 ℃/S^0.05 ℃/S,and there is the medium temperature bainite transition region with the cooling rate being 0.1 ℃/S^7 ℃/S,while the low temperature martensite transitions region exists at cooling rate of 20 ℃/S ~80 ℃/S;the hardness becomes larger with increasing the cooling rate.The hardness under cooling rate of 0.015 ℃/S is 199 HV,and the hardness at the cooling rate of 80 ℃/S is 564HV,providing reference for obtaining the reasonable weld technology.