MICROSTRUCTURE AND PROPERTIES OF SURFACE REMELTED PM STAINLESS STEEL

1 WROŃSKA Agata
Co-authors:
1 DUDEK Agata 2 NAPADŁEK Wojciech
Institutions:
1 Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, Institute of Materials Engineering, Czestochowa, Poland, UK
2 Military University of Technology, Faculty of Mechanical Engineering, Institute of Motor Vehicles and Transportation, Warsaw, Poland, UK
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1102-1107
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
139 views / 25 downloads
Abstract

The aim of this study was to examine the effects of surface treatment with high energy sources on the microstructure and properties of austenitic-ferritic stainless steel sintered in dissociated ammonia. The multi-phase sinters examined in the study were prepared from two types of water atomized steel powders: 304L and 434L. Surface remelting was conducted using two devices: electric arc (GTAW method) and Nd:YAG pulsed laser. The following research methods were used in order to determine microstructure and basic properties of sintered steel after remelting: optical microscopy, X-ray phase analysis, microhardness and surface roughness measurements, tribological and electrochemical tests. It was found that remelting process leads to formation of the homogeneous structure of surface layer without porosity. The microstructure of laser remelted surface layer was finer than after arc remelting but in both cases X-ray analysis revealed only the presence of austenitic phase. The microhardness of laser-treated layer was slightly higher (322 HV 0.05) than after arc process (312 HV 0.05). The measurements of surface geometry parameters (Ra, Rz, Rmax) showed that roughness obtained after pulsed laser remelting is much higher compared to the sinter in the initial state as a consequence of relief. Wear resistance in the sintered steel after arc remelting was better compared to laser-treated specimens. The major wear mechanism in sinters after remelting was adhesion while in the case of sinter in the initial state, wear was caused by abrasion. Corrosion resistance was higher for sinters after surface treatment as a result of porosity elimination and structure homogenization.

Keywords: sintered stainless steel, surface layer remelting, Nd:YAG laser treatment, GTAW method

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