奥氏体化温度对轧态C61钢显微组织和力学性能的影响

Effect of austenitizing temperature on microstructure and mechanical properties of rolled C61 steel

采用扫描电镜、X射线衍射仪、显微硬度仪及拉伸试验等研究了不同奥氏体化温度对轧态C61钢的显微组织和力学性能的影响。结果表明:奥氏体化温度为950℃的热处理工艺能使轧态C61钢获得良好力学性能,其抗拉强度、屈服强度、伸长率以及断面收缩率分别为1376 MPa、997 MPa、13.8%、62.5%。随奥氏体化温度升高,试验钢的断裂机制从韧性断裂转变为韧性+准解理断裂,奥氏体化温度为950℃时,断口组织均匀且韧性最好。当奥氏体化温度较低时,显微组织中马氏体板条较细小,随着温度的升高,马氏体板条束宽度增大,导致轧态C61钢强度、硬度降低。奥氏体化温度对钢中残留奥氏体含量有所影响,在1000℃时残留奥氏体最多、硬度最低。

Effect of different austenitizing temperatures on microstructure and mechanical properties of rolled C61 steel were studied by means of scanning electron microscopy(SEM), X-ray diffractometer, microhardness tester and tensile test. The results show that the mechanical properties of the rolled C61 steel are good after austenitizing treatment at 950 ℃, and the tensile strength, yield strength, elongation and reduction of area are 1376 MPa, 997 MPa, 13.8% and 62.5%, respectively. With the increase of the austenitizing temperature, the fracture mechanism of the tested steel changes from ductile fracture to ductile quasi-cleavage fracture, when the austenitizing temperature is 950 ℃, the fracture structure is uniform and the toughness is the best. When the austenitizing temperature is lower, the martensite lath in the microstructure is smaller, with the increase of temperature, the width of the martensite lath increases, which leads to the decrease of strength and hardness of the rolled C61 steel. The austenitizing temperatures have an effect on the retained austenite content in the steel, when the austenitizing temperature is 1000 ℃, the retained austenite content of the steel is the most and the hardness is the lowest.