Unravelling thermal history during additive manufacturing of martensitic stainless steel

JOURNAL OF ALLOYS AND COMPOUNDS

卷:857

Article

Chae, Hobyung¹  Huang, E-Wen²  Woo, Wanchuck³  Kang, Suk Hoon³  Jain, Jayant⁴  An, Ke⁵  Lee, Soo Yeol¹ 

[1] Chungnam Natl Univ, Dept Mat Sci & Engn, Daejeon 34134, South Korea

[2] Natl Chiao Tung Univ, Dept Mat Sci & Engn, Hsinchu 30010, Taiwan

[3] Korea Atom Energy Res Inst, Daejeon 34057, South Korea

[4] Indian Inst Technol, Dept Mat Sci & Engn, New Delhi 110016, India

[5] Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA

关键词: Additive manufacturing;    Thermal history;    Phase stability;    Residual stress;    Neutron diffraction;   

DOI  :  10.1016/j.jallcom.2020.157555

来源: Elsevier

【 摘 要 】

In-situ thermal cycling neutron diffraction experiments were employed to unravel the effect of thermal history on the evolution of phase stability and internal stresses during the additive manufacturing (AM) process. While the fully-reversible martensite-austenite phase transformation was observed in the earlier thermal cycles where heating temperatures were higher than A(f), the subsequent damped thermal cycles exhibited irreversible phase transformation forming reverted austenite. With increasing number of thermal cycles, the thermal stability of the retained austenite increased, which decreased the coefficient of thermal expansion. However, martensite revealed higher compressive residual stresses and lower dislocation density, indicating inhomogeneous distributions of the residual stresses and microstructures on the inside and on the surface of the AM component. The compressive residual stresses that acted on the martensite resulted preferentially from transformation strain and additionally from thermal misfit strain, and the decrease in the dislocation density might have been due to the strong recovery effect near the Ac-1 temperature. (C) 2020 Elsevier B.V. All rights reserved.

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