基于FactSage的Fe-15Mn-8Al-0.25C低密度钢的组织及力学性能

Microstructure and mechanical properties of Fe-15Mn-8Al-0.25C low density steel based on FactSage

借助FactSage数值模拟软件对Fe-(10~20)Mn-(5~10)Al-(0~0.5)C系低密度钢的凝固及冷却路径、相变及析出相进行了研究,利用FactSage软件中的FSstel数据库对该体系的垂直截面图进行计算,分析了Mn、Al及C元素对凝固及冷却过程中相变及析出相的影响,并得到了Fe-15Mn-8Al-0.25C低密度钢的平衡凝固相变路径图。结果表明,Fe-15Mn-8Al-0.25C低密度钢中热力学计算出的平衡相有液相、铁素体、奥氏体和κ-碳化物,由1600℃冷却至600℃完整的平衡相变路径为:液相→液相+铁素体→液相+铁素体+奥氏体→铁素体+奥氏体→铁素体+奥氏体+κ-碳化物。C和Mn含量的增加可扩大Fe-15Mn-8Al-0.25C低密度钢奥氏体相区,Al元素增加缩小奥氏体相区。κ-碳化物的析出温度随着Al与C含量的增加而升高,Al与C元素均可促进κ-碳化物析出。Fe-15Mn-8Al-0.25C低密度钢800℃时效3 h后的抗拉强度为602 MPa,屈服强度为520 MPa,断后伸长率为28.6%,时效5 h后的抗拉强度为729 MPa,屈服强度为685 MPa,断后伸长率为22.4%,随着时效时间增加,试验钢的强度增加,断后伸长率降低。Fe-15Mn-8Al-0.25C低密度钢的密度为6.99 g/cm,相比普通钢材减重效果达10.4%。

Solidification and cooling path,phase transformation and precipitates of Fe-(10-20)Mn-(5-10)Al-(0-0.5)C low density steel were simulated by FactSage software.The vertical sections of this system were calculated by using the FSstel database of FactSage software.Based on these vertical sections,the influence of Mn,Al and C on phase transformation and precipitates was analyzed during solidification and a diagram of the phase-transformation path of the Fe-15 Mn-8 Al-0.25 C low density steel was obtained during equilibrium solidification.The results indicate that the equilibrium phases of the Fe-15 Mn-8 Al-0.25 C steel calculated by thermodynamics include liquid,ferrite,austenite andκ-carbide.The full-phase transformation path of the Fe-15 Mn-8 Al-0.25 C steel cooled from 1600℃to 600℃is as follows:liquid→liquid+ferrite→liquid+ferrite+austenite→ferrite+austenite→ferrite+austenite+κ-carbide.The increase of C and Mn content can expand the austenite phase zone of the Fe-15 Mn-8 Al-0.25 C steel,and the increase of Al element can reduce the austenite phase zone.The precipitation temperature ofκ-carbide increases with the increase of Al and C content,and Al and C can promote the precipitation ofκ-carbide precipitation.The tensile strength of the Fe-15 Mn-8 Al-0.25 C steel aged at 800℃for 3 h is 602 MPa,the yield strength is 520 MPa,the elongation after fracture is 28.6%,the tensile strength aged at 800℃for 5 h is 729 MPa,the yield strength is 685 MPa,and the elongation after fracture is 22.4%.With the increase of aging time,the strength of the tested steel increases and the elongation after fracture decreases.The density of the Fe-15 Mn-8 Al-0.25 C steel is 6.99 g/cm~3,which is 10.4%weight lighter than common steel.