摘要
中锰钢作为第三代先进高强钢的典型代表之一,其异质结构设计是突破强度-塑性倒置矛盾的关键途径。基于0.2C-5Mn-1Al-0.5Si(质量分数,%)中锰钢,通过950℃-14 h的渗碳与790℃-25 s的盐浴再奥氏体化协同工艺,在0.2C-5Mn钢中成功构建了跨尺度梯度异质结构,表层为FCC(面心立方)/BCC(体心立方)纳米片层双相组织,心部为马氏体基体,两者通过表层碳质量分数0.8%向心部递减至0.2%的连续碳质量分数梯度实现力学性能的耦合。结合DICTRA相变热力学模拟、TEM-EDS(transmission electron microscope-energy dispersive spectrometer)界面表征及显微硬度映射,揭示了渗碳温度(950~1050℃)与再奥氏体化温度(750~790℃)再对双相界面特性及元素扩散动力学的调控规律。结果表明,渗碳工艺使表层碳浓度梯度化,诱发形成厚度为615~1000μm的珠光体层,为后续奥氏体重构提供初始碳势场;在750~810℃-25 s的短时再奥氏体化过程中,锰元素的短程扩散导致FCC相富锰(质量分数为14%)与BCC相贫锰(质量分数为2%~5%)的界面成分偏聚,通过降低层错能与局部稳定奥氏体TRIP(transformation-induced plasticity)效应,实现强塑协同提升(表层硬度为500HV,心部硬度为400HV)。结果为基于扩散调控的梯度异质结构设计与性能优化提供了理论依据。
As a typical representative of the third-generation advanced high-strength steel,medium manganese steel has the heterogeneous structure design as a key approach to break through the strength-plasticity inversion contradiction.Based on 0.2C-5Mn-1Al-0.5S(i mass fraction,%)medium manganese steel,a cross-scale gradient heteroge⁃neous structure was successfully constructed in 0.2C-5Mn steel through a combined process of carburizing at 950℃for 14 h and re-austenitizing in salt bath at 790℃for 25 s.The surface layer is a FCC(face-centered cubic)/BCC(body-centered cubic)nanolamellar duplex structure,while the core is a martensitic matrix.The mechanical properties are coupled through a continuous carbon mass fraction gradient from 0.8%at the surface to 0.2%at the core.By combining DICTRA phase transformation thermodynamic simulation,TEM-EDS interface characterization and microhardness mapping,the regulation laws of carburizing temperature ranging from 950℃to 1050℃and reaustenitizing temperature ranging from 750℃to 790℃on the characteristics of the duplex interface and the kinetics of element diffusion were revealed.The research results show that the carburizing process makes the carbon mass fraction gradient at the surface,inducing the formation of a pearlite layer with a thickness of 615μm to 1000μm,which pro⁃vides an initial carbon potential field for the subsequent austenite reconstruction.During the short-time reaustenitizing pro⁃cess at 750℃to 810℃for 25 s,the short-range diffusion of Mn elements leads to the interface composition segregation of the FCC phase rich in Mn(mass fraction of 14%)and the BCC phase poor in Mn(mass fraction of 2%to 5%).By reducing the stacking fault energy and locally stabilizing austenite(TRIP effect),the strength and plasticity are syn⁃ergistically enhanced(surface hardness of 500HV,core hardness of 400HV).The results provide a theoretical basis for the design and performance optimization of gradient heterogeneous structures based on diffusion control.
作者
王策
李涛
定巍
李岩
韩强
WANG Ce;LI Tao;DING Wei;LI Yan;HAN Qiang(School of Rare Earth Industry,Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China;School of Materials Science and Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,Nei Mongol,China;Inner Mongolia Key Laboratory of New Metal Material,Baotou 014010,Nei Mongol,China;Key Laboratory of Green Extraction and Efficient Utilization of Light Rare-Earth Resources(Inner Mongolia University of Science and Technology),Ministry of Education,Baotou 014010,Nei Mongol,China)
出处
《钢铁》
北大核心
2025年第9期146-156,共11页
Iron and Steel
基金
国家自然科学基金资助项目(52464052)
内蒙古自治区自然科学基金资助项目(2024MS05012)。
关键词
中锰钢
FCC/BCC双相
异质结构
渗碳工艺
再奥氏体化
界面特性
珠光体
组织演变
medium manganese steel
FCC
BCC dual-phase
heterogeneous structure
carburizing process
reaustenitization
interface characteristics
pearlite
microstructural evolution
