SPINODAL DECOMPOSITION OF PRECIPITATION HARDENING Fe-17Cr-4Ni-4Cu STAINLESS STEEL AT 475 °C

  • Xue Ma School of Materials Science and Engineering, Shenyang Ligong University, Shenyang ,China
  • Zhijun Wang China Institute of Atomic Energy, Beijing, China
  • Xuezhu Tong School of Materials Science and Engineering, Shenyang Ligong University, Shenyang ,China
  • Xaoming Du School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159, People’s Republic of China
  • Tianfu Li China Institute of Atomic Energy, Beijing, China
  • Rongdeng Liu China Institute of Atomic Energy, Beijing, China
  • Yuntao Liu China Institute of Atomic Energy, Beijing, China
  • Dongfeng Chen China Institute of Atomic Energy, Beijing, China
Keywords: stainless steel, age hardening, spinodal decomposition, Cu-rich phase

Abstract

Microstructure evolution and mechanical properties in an Fe-17Cr-4Ni-4Cu alloy aged at 475 °C after different aging times were studied. Conventional transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM) studies revealed the formation of 9R-structure Cu-rich precipitates and Cr-rich α’ phase by spinodal decomposition in the samples aged at 475 °C after 100–1000 h. The fine Cu-rich precipitates and Cr-rich α’ phase by spinodal decomposition lead to a significant increase in the hardness, together in the early stages (100 h). Continued aging to 500 h leads to increased precipitation of the Cr-rich α’, which provides significant strengthening, reaching maximum hardening, despite the continued loss of hardening by weakening by the Ostwald ripening of the Cu-rich precipitates. Extending the aging time to 1000 h leads to substantial reversed austenite transformation and a large number of ripening -copper precipitates that causes softening. The results of the impact tests showed that the major fracture mode was cleavage and/or quasi-cleavage.

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Published
2022-04-06
How to Cite
1.
Ma X, Wang Z, Tong X, Du X, Li T, Liu R, Liu Y, Chen D. SPINODAL DECOMPOSITION OF PRECIPITATION HARDENING Fe-17Cr-4Ni-4Cu STAINLESS STEEL AT 475 °C. MatTech [Internet]. 2022Apr.6 [cited 2022Jun.27];56(2):193–199. Available from: https://mater-tehnol.si/index.php/MatTech/article/view/336

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