材料科学技术(英文版)2022，Vol.115Issue(20) ：40-51.

Beneficial effects of deep cryogenic treatment on mechanical properties of additively manufactured high entropy alloy:cyclic vs single cryogenic cooling

Hongge Li Wenjie Zhao Tian Chen Yongjiang Huang Jianfei Sun Ping Zhu Yunzhuo Lu Alfonso H.W.Ngan Daqing Wei Qing Du Yongchun Zou
材料科学技术(英文版)2022，Vol.115Issue(20) ：40-51.
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Beneficial effects of deep cryogenic treatment on mechanical properties of additively manufactured high entropy alloy:cyclic vs single cryogenic cooling

Hongge Li 1Wenjie Zhao 1Tian Chen 1Yongjiang Huang 1Jianfei Sun 1Ping Zhu 2Yunzhuo Lu 2Alfonso H.W.Ngan 3Daqing Wei 4Qing Du 4Yongchun Zou4
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作者信息

  • 1. School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001,China
  • 2. School of Materials Science and Engineering,Dalian Jiaotong University,Dalian 116028,China
  • 3. Department of Mechanical Engineering,The University of Hong Kong,Hong Kong,China
  • 4. Center of Analysis Measurement and Computing,Harbin Institute of Technology,Harbin 150001,China
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Abstract

Additively manufactured(AM)metallic materials commonly possess substantial tensile surface residual stress,which is detrimental to the load-bearing service behavior.Recently,we demonstrated that deep cryogenic treatment(DCT)is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy(HEA)samples fabricated by laser melting deposition(LMD),by introducing high com-pressive residual stress and deformation microstructures without destroying the AM shape.However,car-rying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process,which are undesirable as the mechanical properties will not be homogeneous within the sample.In this work,we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated CoCrFeMnNi HEA,and improve tensile strength and ductility,compared with single-step DCT of the same cryogenic soaking du-ration.Under cyclic DCT,the thermal stress is re-elevated to a high value at each cryogenic cooling step,leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation,compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over time.The enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the DCT.The results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.

Key words

Additive manufacturing/High entropy alloy/Deep cryogenic treatment/Residual stress/Mechanical properties

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基金项目

国家自然科学基金(521 71 154)

国家自然科学基金(51871076)

National Key Research and Development Programs of China(2018YFB1105200)

National Key Research and Development Programs of China(2019YFA0209904)

Guangdong Province Basic and Applied Research Key Projects(2020190718102)

National Key Research and Development Programme,Ministry of Science and Tech-nology of China(2019YFA0209)

出版年

2022
材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCDSCI
影响因子：0.657
ISSN：1005-0302
参考文献量34
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