Article

Journal of Materials Engineering and Performance

, Volume 21, Issue 8, pp 1708-1713

Effects of Temperature on Microstructure and Wear of Salt Bath Nitrided 17-4PH Stainless Steel

  • Jun WangAffiliated withSchool of Manufacturing Science and Engineering, Sichuan UniversityNational Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China
  • , Yuanhua LinAffiliated withState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University Email author 
  • , Hongyuan FanAffiliated withSchool of Manufacturing Science and Engineering, Sichuan University
  • , Dezhi ZengAffiliated withState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University
  • , Qian PengAffiliated withNational Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China
  • , Baoluo ShenAffiliated withSchool of Manufacturing Science and Engineering, Sichuan University

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Abstract

Salt bath nitriding of 17-4 PH martensitic precipitation hardening stainless steels was conducted at 610, 630, and 650 °C for 2 h using a complex salt bath heat-treatment, and the properties of the nitrided surface were systematically evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly process condition dependent. When 17-4PH stainless steel was subjected to complex salt bathing nitriding, the main phase of the nitrided layer was expanded martensite (α′), expanded austenite (γN), CrN, Fe4N, and (Fe,Cr) x O y . In the sample nitrided above 610 °C, the expanded martensite transformed into expanded austenite. But in the sample nitrided at 650 °C, the expanded austenite decomposed into αN and CrN. The decomposed αN then disassembled into CrN and alpha again. The nitrided layer depth thickened intensively with the increasing nitriding temperature. The activation energy of nitriding in this salt bath was 125 ± 5 kJ/mol.

Keywords

17-4PH stainless steel complex salt bath nitriding microstructure temperature wear property