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将V-Nb-Mo微合金钢在1200℃固溶处理0.5 h后淬火,然后在不同的温度(500—650℃)回火4 h,或在650℃回火不同时间,用显微硬度判定等温回火和等时回火时析出碳化物强化机制的转变点,用三维原子探针(3DAP)表征碳化物的析出特征,并测量其等效半径r_p.根据第二相与位错交互作用的强化理论,共格应变强化主导切过机制,计算了位错切过向绕过机制转变时第二相的尺寸.结果表明,3DAP测量和强化理论计算得到的第二相的临界转变半径十分吻合,约为1 nm,表明用共格应变强化切过机制可以很好地预测析出强化作用最显著时第二相的尺寸.
The V-Nb-Mo microalloyed steel was solution treated at 1200 ℃ for 0.5 h, then quenched at different temperatures (500-650 ℃) for 4 h, or tempered at 650 ℃ for different times, and then determined by microhardness Isothermal tempering and isothermal tempering precipitation of carbide strengthening mechanism of the transition point, the use of three-dimensional atom probe (3DAP) characterization of carbide precipitation characteristics, and measure the equivalent radius r_p.According to the interaction of the second phase and dislocation , The size of the second phase in the transition from dislocation to the bypass mechanism was calculated.The results show that the critical transition radius of the second phase calculated by 3DAP measurement and enhancement theory is very large Which is approximately 1 nm. It is indicated that the size of the second phase can be predicted well by the coherent strain strengthening and cleaving mechanism.