淬火温度对780 MPa级Ti-Nb-B微合金化水电用钢组织和力学性能的影响

研究了淬火温度对780 MPa级水电用钢(/%:0.09C,0.10Si,1.50Mn,0.009P,0.002S,0.90Cr,0.20Ni,0.023Ti,0.004Nb,0.001 0B)组织和力学性能的影响。结果表明,试验钢不同温度淬火后均得到了板条贝氏体组织,随着淬火温度910℃升高至950℃,奥氏体平均晶粒从9.1μm长大到16.6μm,试验钢回火后基本保持了淬火态的板条结构。淬火温度在910～950℃试验钢的强度随着淬火温度的升高先增大后减小,并在930℃时达到最大,试验钢冲击韧性和断后延伸率与强度有着相同的变化规律。在930℃淬火,610℃回火的工艺参数条件下,获得最佳的力学性能:屈服强度为802 MPa,抗拉强度为858 MPa,伸长率为19%,-40℃冲击功为238 J。

Effect of Quenching Temperature on Microstructure and Mechanical Properties of 780 MPa Grade Ti-Nb-B Microalloying Hydroelectric Steel

The effect of quenching temperatures on microstructure and mechanical properties of 780 MPa grade hydroelectric steel(/% ：0. 09C,0. 10Si,l.50Mn,0.009P,0.002S,0. 90Cr,0.20Ni,0.023Ti,0.004Nb,0.0010B) was investigated. The results showed that the tested steel can transform into lath bainite microstructure when the steel was quenched at different temperatures, and the average grain size of prior austenite grows from 9.1 μm to 16.6 μm with increasing quenching temperature from 910 °C to 950°C , the microstructure of the tested steel after tempering is basically maintained a lath structure after quenching. When the quenching temperature is between 910 °C and 950°C ,with increasing quenching temperature ,the strength of the tested steel increases firstly then decreases and the maximum value reaches at 930 °C ,and variation of the impact toughness and elongation of tested steel are identical compared with the strength. The optimum mechanical properties are obtained when quenching at 930°C. and tempering at 610 °C , the yield strength is 802 MPa, tensile strength 858 MPa and elongation 19% with the Charpy impact energy 238 J at -40 °C .