Guo Guangshun, Wang Mingming, Ji Hongchao, Zhang Xiaoyan, Li Dongdong, Wei Chenyang, Zhang Fucheng
College of Mechanical Engineering, North China University of Science and Technology, Tangshan 063210, China.
School of Materials Science and Engineering, Zhejiang University, Hangzhou 310030, China.
Materials (Basel). 2024 Feb 3;17(3):732. doi: 10.3390/ma17030732.
Single-pass isothermal hot compression tests on four medium-Mn steels with different C and Al contents were conducted using a Gleeble-3500 thermal simulation machine at varying deformation temperatures (900-1150 °C) and strain rates (0.01-5 s). Based on friction correction theory, the friction of the test stress-strain data was corrected. On this basis, the Arrhenius constitutive model of experimental steels considering Al content and strain compensation and hot processing maps of different experimental steels at a strain of 0.9 were established. Moreover, the effects of C and Al contents on constitutive model parameters and hot processing performance were analyzed. The results revealed that the increase in C content changed the trend of the thermal deformation activation energy with the true strain. The value of 2C7Mn3Al increased by about 50 KJ/mol compared with 7Mn3Al at a true strain greater than 0.4. In contrast, increasing the Al content from 0 to 1.14 wt.% decreased the activation energy of thermal deformation in the true strain range of 0.4-0.9. Continuing to increase to 3.30 wt.% increased the Q of 7Mn3Al over 7Mn by about 65 KJ/mol over the full strain range. In comparison, 7Mn1Al exhibited the best hot processing performance under the deformation temperature of 975-1125 °C and strain rate of 0.2-5 s. This is due to the addition of C element reduces the δ-ferrite volume fraction, which leads to the precipitation of κ-carbides and causes the formation of microcracks; an increase in Al content from 0 to 1.14 wt.% reduces the austenite stability and improves the hot workability, but a continued increase in the content up to 3.30 wt.% results in the emergence of δ-ferrite in the microstructure, which slows down the austenite DRX and not conducive to the hot processing performance.
使用Gleeble - 3500热模拟机，在不同变形温度（900 - 1150℃）和应变速率（0.01 - 5s⁻¹）下，对四种不同C和Al含量的中锰钢进行了单道次等温热压缩试验。基于摩擦修正理论，对试验应力 - 应变数据的摩擦进行了修正。在此基础上，建立了考虑Al含量和应变补偿的试验钢的Arrhenius本构模型以及不同试验钢在应变为0.9时的热加工图。此外，分析了C和Al含量对本构模型参数和热加工性能的影响。结果表明，C含量的增加改变了热变形激活能随真应变的变化趋势。在真应变大于0.4时，2C7Mn3Al的热变形激活能值比7Mn3Al增加了约50kJ/mol。相反，将Al含量从0增加到1.14wt.%，在真应变范围0.4 - 0.9内降低了热变形激活能。继续增加到3.30wt.%，在整个应变范围内，7Mn3Al的热变形激活能比7Mn增加了约65kJ/mol。相比之下，7Mn1Al在975 - 1125℃变形温度和0.2 - 5s⁻¹应变速率下表现出最佳的热加工性能。这是因为添加C元素降低了δ - 铁素体体积分数，导致κ - 碳化物析出并引起微裂纹形成；Al含量从0增加到1.14wt.%降低了奥氏体稳定性并改善了热加工性能，但含量继续增加到3.30wt.%会导致组织中出现δ - 铁素体，减缓奥氏体动态再结晶，不利于热加工性能。
