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.

References

1 H. L. Gao, Y. Liang, H. Wang, B. Hu, Effect of Aging processes on Mechanical Property and Microstructure of 17-4PH Stainless Steel, Heat Treatment, 34 (2019) 1, 36-38, doi: 10.3969/j.issn.1008-1690.2019.01.009.
2 D. W. Deng, R. Chen, X. Tian, D. Y. Wang, Influence of heat treatment on microstructure and properties of 17-4PH martensitic stainless steel, Heat Treatment of Metals, 38(2013) 4, 32-36, doi: 10.13251/j.issn.0254-6051.2013.04.013.
3 H. X. Wang, J. Hu, J. Bao, Y. M. Wu, Effect of Chemical composition and Heat Treatment Process on Mechanical Properties of Steel 17-4PH, Special Steel Technology, 14 (2008) 2, 26-30, doi: 10.16883/j.cnki.issn1674-0971.2008.02.005.
4 Y. Zhao, Y. H. Guo, K. Hou, Effect of Heat Treatment Processes on Mechanical Properties of 17-4PH Stainless Steel,Materials for Mechanical Engineering, 33(2009)5, 5-8, doi:10.1016/S1003-6326(09)60084-4.
5 B. Chen, H. F. Chen, Z. M. Wang, Present Situation and Development Trend of 17-4PH Stainless Steel, Journal of Shanghai Institute of Technology (Natural Science), 16(2016) 1, 83-87, doi: 10.3969/j.issn.1671-7333.2016.01.014.
6 H. Zou, J. Wang, C. Li, R.L.Zuo S.Y.Qiu, B.L. Shen, Study on Microstructure Transformation of 17-4PH Stainless Steel after Long-Term Aging at 350℃, Nuclear Power Engineering, 26 (2005) 4, 397-401, doi: 10.1111/j.1745-7254.2005.00175.x .
7 C. N. Hsiao, C. S. Chiou, J. R. Yang,Aging reactions in a 17-4 PH stainless steel,Materials Chemistry and Physics, 74(2002)2,134 -142,doi:10.1016/S0254-0584(01)00460-6.
8 X. D. Lin, Q. J. Peng, E. H. Han, W. Ke, Review of Thermal Aging of Nuclear Grade Stainless Steels,Journal of Chinese Society for Corrosion and Protection, 37(2017)2, 81-92, doi: 10.11902/1005.4537.2016.073.
9 W. You, J. H. Lee, S. K. Shin, B. H. Choe, U. Paik, J. H. Lee,Embrittlement Fracture in a 17-4 PH Stainless Steel after Aging at 400°C, Materials Science Forum, 516(2005) 973, 241-244, doi: 10.4028/www.scientific.net/MSF.486-487.241.
10 G. Yeli, M. A. Auger, K. Wilford, G. D.W. Smith, P. A. J. Bagot, M. P. Moody, Sequential nucleation of phases in a 17-4PH steel: Microstructural characterisation and mechanicalproperties,Acta Materialia, 125 (2017),38-49, doi: 10.1016/j.actamat.2016.11.052.
11 K. L. Weng, H. R. Chen, J. R.Yang,The low-temperature aging embrittlement in a 2205 duplex stainless steel, Aterials Science and Engineering A, 379 (2004) 1-2,119-132, doi: 10.1016/j.msea.2003.12.051.
12 H.R. Habibi Bajguirani, M. L. Jenkins,High-resolution electron microscopy analysis of the structure of copper precipitates in a martensitic stainless steel of type PH 15-5, Philosophical Magazine Letters A, 73 (1996) 4, 155-162, doi: 10.1080/095008396180786.
13 P. J. Othen, M. C. Jenkins, G. D. W. Smith, W. J. Phythian, High-resolution electron microscopy studies of the structure of Cu precipitates in α-Fe, Philosophical Magazine A, 70 (1994) 1, 1-24, doi: 10.1080/01418619408242533.
14 H.R. Habibi Bajguirani, The effect of ageing upon the microstructure and mechanical properities of type 15-5PH stainless steel, Materials Science and Engineering A, 338 (2002) 1-2, 142-159, doi: 10.1016/s0921-5093(02)00062-X.
15 M. Murayama, Y. Katayama, K. Hono,Murayama M, Hono K, Katayama Y. Microstructural evolution in a 17-4 PH stainless steel after aging at 400℃, Metall Mater Trans A, 30 (1999) 2,345-353, doi: 10.1007/s11661-999-0323-2.
16 T. R. Leax, S. S. Brenner, J. A.Spitznagel, Atom probe examination of thermally ages CF8M cast stainless steel, Metallurgical Transactions A, 23 (1992) 10, 2725-2736, doi:10.1007/BF02651752.
17 H. Ramanarayan, T. A. Abinandanan,Grain boundary effects on spinodal decomposition :ⅡDiscontinuous microstructures, Acta Materialia, 52 (2004) 4, 921-930, doi: 10.1016/j.actamat.2003.10.028.
18 X. W. Li, Z. M. Zhang, X. G. Li, C. G. Kong, K. Guo, Influence of Microstructure on Impact Toughness and Pitting Sensitivity of 17-4PH Martensitic Stainless Steel, Corrosion & Protection 41(2020) 9, 55-59, doi: 10.11973/fsyfh-202009010.
19 X. Yang, The properties and microstructures of 17-4 PH stainless steel (Dissertation in Chinese), Harbin Engineering University, (2007), doi: 10.76666/d.y1211934.
20 A. P. Sorochak, P. O. Maruschak, O. P. Yasniy, T. Vuherer, S. V. Panin, Evaluation of dynamic fracture toughness parameters of locomotive axle steel by instrumented Charpy impact test, Fatigue & Fracture of Engineering Materials & Structures, 40 (2017) 4, 512-522, doi: 10.1111/ffe.12510.
21 J.H. Pan, Dynamic Fracture Behavior of Pressure Vessel Metal Materials under Impact Loads (Dissertation in Chinese),University of Science and Technology of China, (2013), doi: 10.7666/d.Y2280
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 2025Feb.11];56(2):193–199. Available from: https://mater-tehnol.si/index.php/MatTech/article/view/336