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采用热力模拟试验机对超纯21%Cr铁素体不锈钢进行了单道次压缩试验。研究了在650~1 000℃范围内铁素体不锈钢的热变形行为,确定了流变应力、变形温度和变形速率之间的关系及组织演变规律,并建立了变形抗力数学模型。结果表明,超纯铁素体不锈钢在试验温度范围内的热变形软化机制以动态回复为主。在800℃以下变形时,铁素体晶粒内部出现剪切变形带。随着温度的降低和压下量的增加试样中亚晶粒得到细化,位错密度增加。
A single pass compression test was carried out on the ultrapure 21% Cr ferritic stainless steel by using a thermodynamic simulator. The thermal deformation behavior of ferritic stainless steel in the temperature range from 650 ℃ to 1 000 ℃ was studied. The relationship between the flow stress, the deformation temperature and the deformation rate and the evolution of microstructure were confirmed. The mathematical model of deformation resistance was established. The results show that the thermal deformation softening mechanism of ultrapure ferritic stainless steel in the experimental temperature range is dominated by dynamic recovery. When deformed below 800 ℃, shear deformation bands appear in the ferrite grains. With the decrease of the temperature and the increase of the reduction, the subgrains in the sample are refined and the dislocation density is increased.