摘要
激光粉末床熔融(laser powder bed fusion,LPBF)因其优异的成形能力与组织细化潜力,为高性能轻质钢的制备提供了新途径。然而,目前针对高Ni含量Fe-Mn-Al-C系轻质钢的LPBF成形研究匮乏,且B2相演变规律及其对力学性能的影响机制尚不明确。以Fe-30Mn-11Al-12Ni-1C轻质钢为研究对象,对比分析了打印态和热处理后基体组织、B2相的形貌、尺寸及分布演变规律,建立了LPBF成形轻质钢微观组织与力学性能的关系。在激光功率95 W、扫描速度800 mm/s的条件下,成功制备出致密度达99.2%的无缺陷样品,并通过1100℃和1200℃热处理对打印态样品进行组织调控。结果表明,打印态轻质钢以FCC-γ奥氏体相为主,B2相呈棱角分明多边形状(平均尺寸68 nm),沿晶界不连续分布,面积占比12.43%。经1100℃热处理后,B2相转变为短棒状(平均尺寸0.93μm),均匀分布于晶内及晶界,面积占比显著提升至52.14%;1200℃热处理则促使B2相形成条带状形貌(平均尺寸1.89μm),面积占比降至41.03%。力学性能测试显示,1100℃热处理后试样显微硬度(468.5HV0.2)、屈服强度(930.2 MPa)和抗拉强度(1012.6 MPa)显著提升,但伸长率急剧降低至0.88%。研究表明,B2相含量与尺寸的增加通过第二相强化机制提升了强度,但其硬脆特性导致基体塑性急剧恶化。
Laser powder bed fusion(LPBF)offers a novel pathway for enhancing the performance of lightweight steels through its superior forming capability and microstructure refinement potential.However,current research lacks systematic investigation on LPBF processing of Fe-Mn-Al-Ni-C lightweight steels with high Ni content,while the evolution mechanism of B2 phase and its influence on mechanical properties remain unclear.This study investigates Fe-30Mn-11Al-12Ni-1C lightweight steel through comparative analysis of as-built and heat-treated specimens,focusing on matrix microstructure evolution,B2 phase morphology,dimensional characteristics,and spatial distribution.A defect-free sample with 99.2%relative density was successfully fabricated under optimized parameters(laser power at 95 W,scanning speed at 800 mm/s),followed by microstructure regulation through 1100℃and 1200℃heat treatments.The results reveal that the as-printed steel predominantly consists of FCC-γaustenite phase,with angular polygonal B2 particles(average size at 68 nm)discontinuously distributed along grain boundaries,occupying 12.43%area fraction.After 1100°C treatment,B2 phase transforms into short rodlike morphology(average length at 0.93μm)with homogeneous intra-and intergranular distribution,significantly increasing its area fraction to 52.14%.The 1200°C treatment induces banded B2 phase formation(average length at 1.89μm),reducing area fraction to 41.03%.Mechanical characterization demonstrates that 1100°C-treated specimens exhibit enhanced microhardness(468.5HV0.2),yield strength(930.2 MPa),and ultimate tensile strength(1012.6 MPa),but suffer from severe ductility reduction(elongation at 0.88%).The study elucidates that increased B2 phase content and coarsening strengthen materials via secondary phase strengthening mechanism,while their inherent brittleness critically deteriorates matrix plasticity.
作者
张利
李云飞
曲星霖
曹利
李晓峰
ZHANG Li;LI Yunfei;QU Xinglin;CAO Li;LI Xiaofeng(School of Materials Science and Engineering,North University of China,Taiyuan 030051,China;Institute of Special Metal Materials and Equipment,North University of China,Taiyuan 030051,China)
出处
《粉末冶金工业》
北大核心
2025年第4期62-71,共10页
Powder Metallurgy Industry
基金
国家自然科学基金资助项目(52375393)
山西省科技创新人才团队资助项目(202304051001029)
山西省科技成果转化引导专项资助项目(202204021301048)
第九届青年人才托举工程(2023QNRC001)。
关键词
激光粉末床熔融
轻质钢
B2相
热处理
拉伸性能
laser powder bed fusion
lightweight steel
B2 phase
heat treatment
tensile property
作者简介
张利(1991-),男,博士,主要研究方向为金属激光增材制造;通信作者:李晓峰(1986-),男,博士,教授,主要研究方向为金属增材制造、粉末冶金。
