摘要
为探究马氏体转变膨胀应变能对马氏体转变起始温度(M_(s))的影响以及实现对M_(s)的准确预测,采用热膨胀相变仪测定了Fe-C-Ni合金的膨胀曲线,通过三切线法得到M_(s)与奥氏体转变起始温度。采用OM观察和XRD技术分析了成分对马氏体转变后组织和晶格参数的影响规律。通过考虑C成分与Ni成分交互作用,修正了马氏体转变膨胀应变能模型。以马氏体转变化学驱动力(同成分bcc相与fcc相的Gibbs自由能差)与非化学驱动力(奥氏体的剪切应变能、奥氏体的膨胀应变能、马氏体的缺陷储能和奥氏体与马氏体的界面能)之和为0作为判据,计算了Fe-C-Ni体系的M_(s)。结果表明,C含量与Ni含量的增加会促进转变后bcc相的晶格膨胀,Ni含量的增加会使形成的马氏体的板条变细小。在C含量(原子分数)小于1.0%,Ni含量(原子分数)小于20%的Fe-C-Ni合金中,计算得到膨胀应变能在非化学驱动力中的平均占比为41.3%。使用修正后的模型计算Fe-CNi体系的M_(s),预测误差为4.1%。
Ultrahigh-strength steels have been widely used in critical engineering structures in military and civilian applications owing to the combination of ultrahigh strength and excellent toughness. The martensitic transformation start temperature(M_(s)) is an important parameter for designing alloys;it describes the thermodynamic stability and transformation behavior of austenite, affecting the strength and toughness of the alloy. To explore the influence of dilatational strain energy during martensitic transformation on M_(s)and calculate M_(s)in the Fe-C-Ni system, the dilatational curves of Fe-C-Ni alloys are measured using a dilatometer. Three tangents method is used to calculate M_(s)and austenitic transformation start temperature. The influence of composition on microstructure and lattice parameters after martensitic transformation was analyzed using OM and XRD. The dilatational strain energy model in the nonchemical driving force of martensitic transformation is modified considering the interaction between C and Ni components. The M_(s)of Fe-C-Ni system was calculated using a thermodynamic model in which the sum of martensitic transformation chemical driving force(the difference of Gibbs free energy between fcc and bcc phases) and nonchemical driving force(shearing strain energy of austenite, dilatational strain energy of austenite, dislocation stored energy of martensite, and interfacial energy of austenite and martensite)is zero. These results show that increasing C and Ni contents promote lattice expansion of the bcc phase after transformation whereas increasing Ni content reduces the martensite lath. The average proportion of dilatational strain energy of austenite in nonchemical driving force is approximately 41.3% in Fe-C-Ni alloys with atomic fractions of C < 1.0% and Ni < 20%. The prediction error of M;in the Fe-C-Ni system is 4.1% using the modified model.
作者
陈维
陈洪灿
王晨充
徐伟
罗群
李谦
周国治
CHEN Wei;CHEN Hongcan;WANG Chenchong;XU Wei;LUO Qun;LI Qian;CHOU Kuochih(State Key Laboratory of Advanced Special Steel,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;Shanghai Key Laboratory of Advanced Ferrometallurgy,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第2期175-183,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金项目Nos.U1808208
51734002
上海大学省部共建高品质特殊钢冶金与制备国家重点实验室自主课题项目No.SKLASS2020-Z01
上海市科学技术委员会项目No.19DZ2270200。
关键词
Fe-C-Ni体系
马氏体转变起始温度
膨胀应变能
热力学计算
Fe-C-Ni system
martensitic transformation start temperature
dilatational strain energy
thermodynamic calculation
