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研究了固溶处理后不同冷速对轻质Fe-15Mn-10Al-1.0C钢组织及力学性能的影响.结果表明,固溶处理后冷却过程中,奥氏体晶内发生调幅分解形成纳米级晶内κ-碳化物,产生沉淀强化.随着冷却速率的降低,γ/δ晶界形成κ-碳化物,使得油淬和空冷试样的第二相强化效果明显,但水淬试样的综合力学性能最好,强塑积高达50.9 GPa％.拉伸试验过程中,晶界κ-碳化物是试验钢空冷和油淬后产生微孔的初始点,γ和δ晶粒间的变形协调不一致是水淬产生微裂纹的主要原因.计算获得奥氏体层错能为78.99 mJ/m2,变形过程中位错运动切过奥氏体晶内纳米级κ-碳化物,形成大量平面滑移剪切带,为明显平面滑移特征.

The effect of cooling rate after solution treatment on microstructure and mechanical properties of lightweight Fe-15Mn-10Al-1.0C steel was investigated.The results showed that the nanoscale κ-carbide was formed in austenite grains through spinodal decomposition during cooling process of solution treatment and exhibited precipitation strengthening.With the decreasing of cooling rate,κ-carbide was formed in γ/δ grain boundaries,the strengthening effect of second phase was obviously observed in oil-quenched (OQ) and air-cooled (AC) samples.After being solution treated at 1 030 ℃ and water quenched (WQ),the steel possessed an excellent combination of strength and ductility,with the value of product of tensile strength and elongation being over 50.9 GPa％.During tensile deformation,the pore formation of AC and OQ steel started from the precipitated κ-carbide along grain boundaries,the microcracks of WQ steel started from γ/δ grain boundaries,because of the existing deformation mismatch between these two phases.The computation result of SEF in austenite of the lightweight Fe-15Mn-10Al-1.0C steel was 78.99 mJ/m2.The movement dislocations cut across the nanoscale κ-carbide in austenite grains,which led to the formation of uniformly arranged shear bands of austenite.The lightweight Fe-15Mn-10Al-1.0C steel showed the obvious characteristic of planer gliding.