AN OVERVIEW OF SIGMA PHASE FORMATION IN 317L GRADE AUSTENITIC STAINLESS STEEL

1 ALTIERI Welder
Co-authors:
1 FALDINI Sonia 1 VATAVUK Jan
Institution:
1 UPM – Mackenzie Presbyterian University, São Paulo, Brazil, BR
Conference:
26th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 24th - 26th 2017
Proceedings:
Proceedings 26th International Conference on Metallurgy and Materials
Pages:
719-724
ISBN:
978-80-87294-79-6
ISSN:
2694-9296
Published:
9th January 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
100 views / 103 downloads
Abstract

Austenitic Stainless Steel is known as responsible for the largest manufacturing share of stainless steel. Different processes, as well as the addition of alloying elements affects the microstructure, which provides specific properties to each steel grade. One of the microstructural characteristics that affects the austenitic stainless steels properties is related to the intermetallic phases, especially the sigma phase. Its presence and distribution on the microstructure may impair several characteristics of the alloy, such as the reduction of the tenacity and ductility, generating important discussions on engineering. The present paper aims to overview the effects of the presence of the sigma phase in 317L grade austenitic stainless steel, welded, without and with heat treatment at 850 °C and 1080 °C with different exposure times. The effect of the heat treatments was followed by the mechanical tests of hardness and tensile strength. The investigation of the evolution of the microstructure was accompanied by metallographic analysis in samples in the original condition and after heat treatment. The microstructure was revealed by means of electrolytic etching, with subsequent analysis by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy microanalysis techniques. The presence of stabilizing elements of ferrite, chromium and molybdenum tend to accelerate the precipitation of the sigma phase at 850 °C, even at short exposure intervals at this temperature. It was observed a greater hardening, by the precipitation of the sigma phase in the welded region, emphasizing also that its presence is related to a decrease of the resistance and ductility

Keywords: Austenitic stainless steel, delta ferrite, sigma phase, welding.

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