等温淬火对水利工程用YP460钢的组织与力学性能的影响

Effects of Isothermal Quenching on Microstructure and Mechanical Properties of YP460 Steel for Hydraulic Engineering

研究了等温淬火温度和保温时间对YP460钢的显微组织、物相组成、硬度和冲击性能的影响,优化了等温淬火工艺。结果表明：淬火态、250～300℃和325℃等温淬火态YP460钢的显微组织分别为马氏体＋残余奥氏体、下贝氏体＋残余奥氏体和上贝氏体＋残余奥氏体;当等温温度为250、275和300℃时,随着等温保温时间的延长,洛氏硬度呈现逐渐增加的趋势而冲击韧性呈现逐渐降低的特征;而当等温温度为325℃时,洛氏硬度随着保温时间的延长逐渐降低而冲击韧性逐渐升高;相同等温保温时间下,325℃等温淬火态试样的洛氏硬度和冲击韧性都要低于250～300℃等温淬火态试样;YP460钢适宜的等温淬火工艺为300℃保温4～8 h。

The effects of isothermal quenching temperature and holding time on the microstructure, phase composition, hardness and impact properties of YP460 steel were studied, and the isothermal quenching process was optimized. The results show that, the microstructures of the quenched YP460 steel, 250-300 ℃ and 325 ℃ isothermal quenched YP460 steel are martensite and residual austenite, lower bainite ＆ residual austenite, and upper bainite ＆ residual austenite repectively. When the isothermal temperature is 250 ℃, 275 ℃ and 300 ℃, with the isothermal holding time increasing, the Rockwell hardness increases gradually and the impact toughness gradually decreases, and when the isothermal temperature is 325℃, the rockwell hardness decreases gradually and the impact toughness increases gradually with the prolongation of the holding time. Under the same isothermal insulation time, the Rockwell hardness and impact toughness of the isothermal quenched sample at 325 ℃ are lower than those of the samples isothermal quenching at 250-300 ℃. The suitable isothermal quenching process for YP460 steel is 4-8 h at 300 ℃.