低碳钢铁素体相区变形特性

Deformation Characteristics of a Plain Carbon Steel in Ferrite Phase Range

采用平面应变压缩试验研究了Ｑ２３５级别低碳钢铁素体相区在５５０～７２０℃，应变速率 在５×１０－４～１０Ｓ－１范围的热变形特性．结果表明，在铁素体相区范围，所有流变曲线都观察到了 峰值应力的出现及随后“应力软化”进入稳态的现象，意味着动态回复或动态再结晶的发生．应 变速率越低，形变温度越高，出现应力峰值的临界应变量越小．Ｚ参数及应力峰值σｍ数值计算得 到Ｑ２３５级别低碳钢平面应变压缩的铁素体热变形激活能为３００．４ｋＪ／ｍｏｌ．

The hot deformation characterishcs of Q235 class low carbon steel were investigated by plane strain compression test within the temperature range between 550℃ and 720℃, i.e. ferrite phase range, with a strain rate range of 5×10-4 s-1 to 10s-1. The experimental results show that, in the ferrite phase range, the flow wstresses of strain-stress curves gradually increases to a peak followed by a strain softening and then a steady state at high strain, indicating that dynamic recovery or dynamic recrystallization occurs in the steel. The slow- er the strain rate, and/or the higher the deformation temperature, the smaller the strain corresponding to the peak stress. The hot deformation activation enemy (Q) of the steel tested is calculated to be 300.4 kJ/mol from the values of Zener-Hollomon parameters and peak stresses.