电子束选区熔化成形高氮钢的微观组织与力学性能  

Microstructure and mechanical properties of high nitrogen steel fabricated by selective electron beam melting

作　　者：张佳豪 王岩 李花兵 冯浩 魏瑛康 王建勇 张亮亮 刘世锋[1] ZHANG Jiahao;WANG Yan;LI Huabing;FENG Hao;WEI Yingkang;WANG Jianyong;ZHANG Liangliang;LIU Shifeng(School of Metallurgical and Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,Shaanxi,China;School of Metallurgy,Northeastern University,Shenyang 110819,Liaoning,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055 [2]东北大学冶金学院,辽宁沈阳110819

出　　处：《钢铁》2024年第6期122-134,共13页Iron and Steel

基　　金：国家自然科学基金青年基金资助项目(52304357,5230041344);中国博士后科学基金资助项目(2022MD723810);咸阳市二〇二一年秦创原科技创新专项资助项目(2021ZDZX-GY-0008)。

摘　　要：高氮奥氏体不锈钢(high nitrogen austenitic stainless steel)广泛应用于飞机叶片、特种车身及涡轮等具有复杂结构的部件。电子束选区熔化(SEBM)技术具有更高的预热温度(最高达1200℃)和更高的能量利用率等优势,能够有效解决传统材料加工方法制备高氮钢组织粗大、组织分布不均匀的问题,有望大幅改善高氮钢力学性能,能够实现复杂构件的一体化成形。通过改变SEBM的电子束束流和扫描速度制备高氮钢试样,研究了工艺参数对打印态试样氮含量、致密度、物相组成、微观组织演变和拉伸性能的影响规律。结果表明,试样的氮含量较粉末均出现不同程度减少,随着能量密度的增加而减小;微观组织主要由奥氏体、铁素体、晶间σ相、亚稳态M2(C,N)组成;通过改变工艺参数可以调控奥氏体、铁素体和σ析出相的尺寸;随着电子束束流增加,奥氏体基体先变大后变小,奥氏体晶界析出σ相尺寸先变小后增大且晶内小尺寸析出物逐渐变少。随着扫描速度的增大,熔池热输入减少、能量密度减小,晶界处σ相析出物逐渐变大,奥氏体基体逐渐变小。当能量密度增大时,试样的极限抗拉强度和屈服强度先上升后降低。当电子束束流为23 mA、扫描速度为6 m/s、相应能量密度为57.50 J/mm^(3)时,高氮钢的综合力学性能最佳,极限抗拉强度为1200 MPa,屈服强度为868 MPa,伸长率为6.5%。High nitrogen austenitic stainless steel(HNASS)is widely used in aircraft blades,special car bodies and turbine components with complex structure.Selective electron beam melting(SEBM)technology has a higher preheating temperature(up to 1200℃)and higher energy utilization and other advantages,can effectively solve the traditional materials processing methods for the preparation of high nitrogen steel organization coarse,uneven tissue distribution,is expected to significantly improve the mechanical properties of high nitrogen steel,can realize the integration of complex components forming.The high-nitrogen steel specimens were prepared by changing the electron beam current and scanning speed of SEBM,and the effects of process parameters on the nitrogen content,densification,physical phase composition,microstructure evolution and tensile properties of the printed specimens were investigated.The results show that the nitrogen content of the specimen is reduced to different degrees compared with that of the powder,which decreases with the increase of energy density.The microstructure is mainly com‐posed of austenite,ferrite,intergranularσphase,and substable M2(C,N).The size of austenite,ferrite,andσprecipitation phases can be adjusted by changing the process parameters.The size of the austenite matrix becomes larger and then smaller with the increase of the e-beam beam current.The size ofσ-phase precipitated at austenite grain boundaries decreases and then increases and the small-sized precipitates in the grain gradually become less.As the scanning speed increases,the melt pool heat input decreases the energy density decreases,theσ-phase precipitates at the grain boundaries gradually become larger,and the austenite matrix gradually becomes smaller.When the energy density increases,the ultimate tensile strength and yield strength of the specimen first increase and then decrease.When the electron beam current is 23 mA,the scanning speed is 6 m/s,and the corresponding energy density is 57.50 J/mm^(3),the comprehe

关 键 词：高氮奥氏体不锈钢 电子束选区熔化 显微组织结构 奥氏体 拉伸性能 

分 类 号：TG142.71[一般工业技术—材料科学与工程]