Abstract

We have analyzed the effect of the final rolling temperature on the morphology, mechanical properties, carbide nanoparticle size, and dislocation density of Ti-Mo ferritic steel. The microstructure was mainly composed of equiaxed ferrite, ultrafine ferrite, and polygonal deformed ferrite, whose three proportions were affected significantly by the final rolling temperature. The change trend of the mechanical strength was in line with the dislocation density under different finishing rolling temperatures, whereas the ferrite grain size change trend was the opposite. There were various types of nanoparticle precipitation in the test steels: interphase precipitation, dispersion, dislocation precipitation, and deformation-induced precipitation. The optimum mechanical properties were obtained at a final rolling temperature of 900 °C. Quantitative analysis showed that the effect of the final rolling temperature on the yield strength was mainly because of dislocation and precipitation strengthening. The toughening mechanism is attributed to the fine grain strengthening of nanoparticles in austenite stage and the precipitation strengthening of ferrite stage.

中文翻译：

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终轧温度对铁素体钢纳米颗粒沉淀行为和增韧机理的影响

摘要

我们分析了终轧温度对Ti-Mo铁素体钢的形态，力学性能，碳化物纳米颗粒尺寸和位错密度的影响。显微组织主要由等轴铁素体，超细铁素体和多边形变形铁素体组成，这三个比例受最终轧制温度的影响很大。在不同的终轧温度下，机械强度的变化趋势与位错密度一致，而铁素体晶粒尺寸的变化趋势则相反。试验钢中有多种类型的纳米颗粒沉淀：相间沉淀，分散，位错沉淀和形变诱发沉淀。在900℃的终轧温度下可获得最佳的机械性能。定量分析表明，终轧温度对屈服强度的影响主要是由于位错和析出强化。增韧机理归因于奥氏体阶段纳米颗粒的细晶粒强化和铁素体阶段的析出强化。