Development of duplex high temperature gas nitriding and low temperature plasma nitriding surface treatments for UNS S31803 duplex stainless steel

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Authors

Colleges, School and Institutes

External organisations

  • University of Sao Paulo
  • Heat Tech Technology for Heat Treatment and Surface Engineering Ltd.

Abstract

Specimens of a UNS S31803 duplex stainless steel were (i) single low temperature plasma nitrided and (ii) high temperature gas nitrided, at 1200°C and low temperature plasma nitrided. Plasma nitriding treatments were carried out at 400°C by 20 h, in a 75%N2+25%H2 atmosphere, duplex surface treatment. The microstructure of the as received material is composed by ferrite and austenitic stringers, aligned in the rolling direction. Light optical microscopy (LOM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron-backscattered diffraction (EBSD) were used to characterize the microstructure. The duplex surface treatment led to the formation of 550 μm thick fully austenitic layer at the surface of the specimens, by transformation of ferrite stringers, and the subsequent plasma nitriding led to the formation of a homogeneous expanded austenite layer, 1144 HV. The single plasma nitrided (LTPN) layer was composed by expanded ferrite (αn) and expanded austenite (γn), with microhardness of 1509 HV and 1362 HV, respectively.

Details

Original languageEnglish
Title of host publicationMaterials Science and Technology Conference and Exhibition 2014, MS and T 2014
Publication statusPublished - 1 Jan 2014
EventMaterials Science and Technology Conference and Exhibition 2014, MS and T 2014 - Pittsburgh, United States
Duration: 12 Oct 201416 Oct 2014

Conference

ConferenceMaterials Science and Technology Conference and Exhibition 2014, MS and T 2014
CountryUnited States
CityPittsburgh
Period12/10/1416/10/14

Keywords

  • Duplex stainless steel, Duplex treatment, High temperature gas nitriding, Low temperature plasma nitriding