Tests of quenching at 900 ℃ with different cooling rates were carried out for a high carbon low alloy wear-resistant steel by using L78 dilatometer.The microstructure of the quenched steel was observed by metallographic microscope,and the hardness was measured by 450SVD digital Vickers hardness tester.The results show that when the cooling rate is less than 0.4 ℃/s,the microstructure of the tested steel is pearlite plus a small amount of ferrite,and the hardness value is 254-313 HV5.When the cooling rate is 0.4 ℃/s,the microstructure is full pearlite and the hardness value is 317 HV5.When the cooling rate is 0.5-1 ℃/s,the microstructure is composed of pearlite,bainite,martensite and retained austenite,and the hardness value is 435-726 HV5.When the cooling rate is 2-3 ℃/s,the microstructure is bainite,martensite and retained austenite,and the hardness value is 726-753 HV5.When the cooling rate reaches 4 ℃/s,the microstructure is martensite and retained austenite,and the hardness is 784 HV5.When the cooling rate further increases to 150 ℃/s,the microstructure has no obvious change,and the hardness value changes little,which is 810-825 HV5.When the cooling rate reaches 180 ℃/s,the hardness value drops to 785 HV5,while the microstructure is still martensite and retained austenite,but the amount of the retained austenite is increased.
关键词
高碳低合金耐磨钢/淬火/冷却速度/显微组织/硬度
Key words
high carbon low alloy wear-resistant steel/quenching/cooling rate/microstructure/hardness
维普
万方数据