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 plane strain compression test was used to study the thermal deformation characteristics of ferritic Q235 low carbon steel at 550-720 ℃ and strain rate of 5 × 10-4-10S-1. The results show that in the range of ferrite phase, the appearance of peak stress and the subsequent “stress softening” into steady state are observed in all the rheological curves, which means the dynamic recovery or dynamic recrystallization occurs. The lower the strain rate is, the higher the deformation temperature is and the smaller the critical strain of the stress peak is. Z parameter and stress peak value σm calculated the Q235 level mild steel plane strain compression ferrite thermal deformation activation energy of 300.4kJ / mol.