增材制造马氏体时效钢的析出行为与强化机制  

Precipitation behavior and strengthening mechanism in an additive manufactured maraging steel

作　　者：刘庆冬 张孟超 刘明洋 刘晓晖 李慧[2] 王泽民 赵波 顾剑锋[1] LIU Qingdong;ZHANG Mengchao;LIU Mingyang;LIU Xiaohui;LI Hui;WANG Zemin;ZHAO Bo;GU Jianfeng(School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;School of Materials Science and Engineering,Shanghai University of Engineering Science,Shanghai 201418,China;Shanghai ESU Laser Technology Co.,Ltd.,Shanghai 201505,China)

机构地区：[1]上海交通大学材料科学与工程学院,上海200240 [2]上海大学材料科学与工程学院,上海200444 [3]上海应用技术大学材料科学与工程学院,上海201418 [4]上海毅速激光科技有限公司,上海201505

出　　处：《钢铁》2024年第6期49-59,共11页Iron and Steel

基　　金：国家重点研发计划资助项目(2018YFA0702900);中核集团领创科研基金资助项目;重庆市自然科学基金资助项目(cstc2021jcyjmsxmX1088)。

摘　　要：为了提升中国增材制造模具的品质和国际竞争力,加速世界向增材制造的转变,从汽车一体化压铸技术对可替换增材制造镶块材料的需求出发,在18Ni300马氏体时效钢的基础上,通过降低Ni含量、调整Co成分、保持Al含量并添加适量Cu的成分设计策略,开发了一种易于增材制造新型合金钢。利用扫描电镜(SEM)、透射电镜(TEM)和原子探针层析技术(APT)等微纳结构表征手段,研究了打印态马氏体时效钢在回火过程中第二相的析出过程和强化机制。结果表明,不同温度回火时,马氏体时效钢表现出明显的析出强化效应,在560℃时达到硬度峰值(约为54HRC),460℃和600℃时的硬度均约为50HRC,两者抗拉强度相近,但后者屈服强度较低,同时伸长率、断面收缩率和室温冲击韧性均大幅度提高,断口表现出明显的塑性断裂。低温(460℃)回火时,出现明显的Ni、Cu等元素的团簇,为富Cu的β-Ni Al相形核早期的存在形式,同时还因调幅分解而出现Cr的成分起伏,并出现纳米薄膜状的奥氏体(γ)相;高温(600℃)回火时,形成纳米β-Ni Al相和细小的富Mo、W、Cr的Laves相,且两者与α-Fe基体分别存在[001]_(β)//[001]_(α)和[1123]_(Laves)//[011]_(α)的位向关系,同时形成有利于塑韧性改善的α+γ的双相组织。低温(460℃)回火时形成的富Ni团簇和富Cr团簇,可能是高温(600℃)回火时β-Ni Al相和Laves相的前驱体,2种形态均是析出强化的主要贡献者。In order to improve the quality and international competitiveness of molds in China and accelerate the application of additive manufacturing in mold field,starting from the demand for replaceable additive manufacturing insert materials in automotive integrated die casting technology,a new type of alloy steel suitable for additive manufacturing was developed based on 18Ni300 maraging steel,by composition optimization strategies of reducing the Ni,adjusting Co,maintaining Al and adding an appropriate amount of Cu.Microstructural characterization techniques such as scanning electron microscopy(SEM),transmission electron microscopy(TEM),and atom probe tomography(APT)were utilized to investigate the precipitation process and strengthening mechanism of the secondary phase during tempering of the as-built martensitic maraging steel.The results showed that,at different tempering temperatures,the martensitic maraging steel exhibited significant precipitation strengthening effects.The hardness reached a peak at 560℃(54HRC),while the hardness at both 460℃and 600℃was approximately 50HRC.Although the tensile strengths were similar,the yield strength was lower at 600℃tempering.Moreover,the elongation and impact toughness were significantly improved,with the fracture surface showing clear plastic fracture characteristics.During low-temperature tempering(460℃),significant clustering of Ni,Cu was observed,indicating the early formation of Cu-richβ-NiAl phase nuclei,along with the compositional fluctuations of Cr and the formation of nano-sized reversed austenite(γ)phase.At high-temperature tempering(600℃),nano-sizedβ-NiAl phase and small Mo-,W-,and Cr-rich Laves phase were formed,exhibiting the orientation relationship of[001]_(β)//[001]_(α)and[1123]_(Laves)//[011]_(α),respectively.Meanwhile,a dual-phase microstructure ofα+γwas formed that is thought to improve plasticity and toughness significantly.The Ni-rich clusters and fluctuations in Cr composition formed at 460℃may serve as precursors for theβ-NiAl a

关 键 词：增材制造 马氏体时效钢 析出强化 β-NiAl相 LAVES相 压铸模 

分 类 号：TG142.1[一般工业技术—材料科学与工程]