Evaluation of composition, microstructure and hardness of additive manufacturing samples based on multi-way powder feeding process
FENG Guang1,2, LI Dong-ling1,2, LIU Zong-xin1,3, SHEN Xue-jing1,2,3, WANG Hai-zhou1,2, JIA Yun-hai*1,2
1. Testing Institute, Central Iron and Steel Research Institute, Beijing 100081, China; 2. Beijing Key Laboratory of Metal Material Characterization, Beijing 100081, China; 3. NCS Testing Technology Co., Ltd., Beijing 100081, China
Abstract：As a new layer-by-layer fusion manufacturing process, the laser-enhanced additive manufacturing technology can be used to prepare metal materials with gradient variation of elemental composition according to the requirements. A gradient composition sample composed of two stainless steel powders with uniform ratios was designed. Firstly, the phase composition and mechanical properties of the material were predicted using thermodynamic calculation software. Then, the sample was prepared by multi-channel powder feeding laser cladding process. Finally, the statistical distribution of fine composition, microstructure and hardness of the gradient material in micro-regions were characterized using micro-zone X-ray fluorescence spectrometer, metallurgical microscope and micro Vickers combined with fluid microprobe strain technology. The results showed that variations of element content, metallographic structure, hardness and mechanical properties in different regions of the gradient component sample were basically consistent with those calculated by thermodynamic software. The influence of elemental composition in component gradient changing regions on the structural state of region and mechanical properties of material was studied. It indicated that the inflection point and steep drop zone of hardness distribution were closely related to the changes of Ni element and the appearance of lath martensite. Meanwhile, the 316L austenite structure showed discontinuous skeleton distribution, while the JY-Fe45A region contained much lath martensite with coarse grain structure. At last, the reason of abnormal mechanical properties in samples was analyzed by combining isostatic pressure-based fluid microprobe strain non-destructive testing method with micro-Vickers. The shortcomings of existing printing process were found.
Rifkin.3D printing scales up technology[J].The Economist,2013,8(2):11-13.
[4]
王迪,杨永强,吴伟辉.光纤激光选区熔化316L不锈钢工艺优化[J].中国激光,2009,36(12):3233-3239.WANG Di,YANG Yong-qiang,WU Wei-hui.Process optimization for 316L stainless steel by fiber laser selective melting[J].Chinese Journal of Lasers,2009,36(12):3233-3239.
[5]
卞宏友,刘伟军,王天然,等.激光金属沉积成形的扫描方式[J].机械工程学报,2006,42(10):170-175.BIAN Hong-you,LIU Wei-jun,WANG Tian-ran,et al.Scanning mode for laser metal deposition shaping[J].Chinese Journal of Mechanical Engineering,2006,42(10):170-175.
[6]
YADROITSEV I,BERTRAND P,SMUROV I.Parametric analysis of the selective laser melting process[J].Applied Surface Science,2007,253(19):8064-8069.
[7]
JEN J Y,LIN M C.Mold fabrication and modification using hybrid processes of selective laser cladding and milling[J].Journal of Materials Processing Tech,2001,110(1):98-103.
李延民,李建国,杨海欧,等.金属零件激光直接成形[J].应用激光,2002,22(2):71-75.LI Yan-min,LI Jian-guo,YANG Hai-ou,et al.Laser direct forming of metal components[J].Applied Laser,2002,22(2):71-75.
[13]
颉芳霞,何雪明,俞经虎,等.生物医用多孔Ti-6Mo合金选择性激光烧结的结构特征和力学行为[J].稀有金属材料与工程,2016,44(6):1477-1482.XIE Fang-xia,HE Xue-ming,YU Jing-hu,et al.Structural characteristics and mechanical behavior of selective laser sintered porous Ti-6Mo alloy for biomedical applications[J].Rare Metal Materials and Engineering,2016,44(6):1477-1482.
