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    轧制成型氧化物弥散强化钢的显微组织特征和拉伸性能

    Microstructure Characterization and Tensile Properties of Oxides Dispersion Strengthened Steel by Rolling

    • 摘要: 用金属快冷气雾化方法直接制备Fe-15Cr-4.5Al-2W-0.3Y-0.3Ti-0.3Zr过饱和固溶体合金粉,经过短时(8 h)球磨后置于铁质包套内,直接轧制得到氧化物弥散强化(ODS)钢,研究了该钢的显微组织特征及不同温度(室温以及400,600,700 ℃)下的拉伸性能。结果表明:轧制可实现ODS钢的成型,且其相对密度达到96%,略高于成分相近的热等静压成型ODS钢,平均晶粒尺寸为0.91 μm,小于成分相近的热等静压成型ODS钢,且无显著的织构特征;轧制成型ODS钢的组织中同时存在Y4Zr3O12、YAlO3和Y2TiO5纳米析出相,分布密度峰值达到2.07×1021 m−3。随着试验温度的升高,轧制成型ODS钢的抗拉强度降低;与成分相近的热等静压成型ODS钢相比,低于600 ℃时轧制成型ODS钢的抗拉强度更高,600 ℃时抗拉强度相近,高于600 ℃时抗拉强度略低;随着试验温度的升高,轧制成型ODS钢的断裂机制由脆性断裂向韧性断裂转变,最后又转变为脆性断裂。

       

      Abstract: Fe-15Cr-4.5Al-2W-0.3Y-0.3Ti-0.3Zr supersaturated solid solution alloy powder was directly prepared by metal rapid cooling gas atomization method. The powder was treated by a short time (8 h) ball milling and then was placed in an iron envelope. The oxides dispersion strengthened (ODS) steel was directly formed by rolling. The microstructure characteristics and the tensile properties at different temperatures (room temperature and 400, 600, 700 ℃) of the rolled ODS steel were studied. The results show that ODS steel could be formed by rolling, and the relative density of the rolled ODS steel was 96%, which was slightly higher than that of hot isostatic pressed ODS steel with similar composition. The average grain size of the rolled ODS steel was 0.91 μm, which was smaller than that of hot isostatic pressed ODS steel with similar composition, and no significant texture feature was found. Y4Zr3O12, YAlO3 and Y2TiO5 nano-precipitates were observed in microstructure and the distribution density peak value of these precipitates reached 2.07×1021 m−3. The tensile strength of the rolled ODS steel decreased with the increase of test temperature. Comparing with that of ODS steel with similar composition formed by hot isostatic pressing, the tensile strength of the rolled ODS steel was higher below 600 ℃, was similar at 600 ℃, and was slightly lower above 600 ℃. With the increase of test temperature, the fracture mechanism of rolled ODS steel changed from brittle fracture to ductile fracture, and finally to brittle fracture again.

       

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