氧化物弥散强化钢的强化机理

Strengthening mechanisms of oxide dispersion strengthened steel

采用粉末冶金法制备出成分为Fe-12.5Cr-2.5W-0.4Ti-0.02V-0.4Y_2O_3(12Cr-ODS,质量分数,%)的铁素体钢.通过电镜观察及力学性能测试等手段研究了12Cr-ODS铁素体钢的组织与性能,并定量计算了不同强化机制对合金屈服强度的贡献.电镜观察发现12Cr-ODS钢为等轴的铁素体组织,平均晶粒尺寸为1.5μm,不同尺寸氧化物在基体中均匀分布.力学性能测试结果表明12Cr-ODS钢具有优异的室温拉伸性能,屈服强度达到738 MPa.合金主要强化机制为氧化物弥散强化、氧化物弥散强化钢加工强化、热错配位错强化和晶界强化机制,各种强化机制计算得到的理论屈服强度为750 MPa,与实测值吻合较好.

An oxide dispersion strengthened （ODS） ferritic steel with the nominal composition of Fe-12.5Cr- 2.5W-0.4Ti-0.02V-0.4Y203 （designated 12Cr-ODS, % by mass） was produced by powder metallurgy. Its microstructure and mechanical properties were investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and mechanical properties testing. Quantitative calculations were performed to find out the contribution of different strengthening mechanisms to the yield strength of the steel. SEM and TEM observations show that the steel exhibits equiaxed ferritic grains, its average size is 1.5 μm, and oxide particles of different sizes appear quite homogeneously distributed in the matrix. Tensile testing results indicate that the steel has superior tensile strength with the high yield strength of 738 MPa at room temperature. Orowan strengthening, work hardening effect of reinforced particles, dislocation strengthening by thermal expansion mismatch, and grain boundary strengthening are the main strengthening mechanisms of the steel. The theoretical yield strength is 750 MPa, which is in good agreement with the experimental data.