Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
ANALYSIS OF THE INFLUENCE OF GTAW WELDING PARAMETERS ON THE MICRO HARDNESS OF DUPLEX STAINLESS STEEL UNS S31803
Submission Author:
Pedro Eduardo Machado Zortéa , ES , Brazil
Co-Authors:
Pedro Eduardo Machado Zortéa, Rodrigo Soares dos Santos, erijanio Silva
Presenter: Pedro Eduardo Machado Zortéa
doi://10.26678/ABCM.COBEM2023.COB2023-1971
Abstract
A duplex stainless steel is a type that joins two microconstituents divided into practically equal proportions to have some advantages. When a steel goes through the welding process it is exposed, in the region where the welding occurs and in the vicinity to high temperatures, which can often change some properties present in the material. A property that often varies after the welding process is hardness, so the increase or decrease of the same by any process must be well evaluated in order not to compromise the applicability. The present study aimed to study the effect of GTAW welding parameters on the variation of the micro hardness of the stainless-steel duplex UNS S31803 through micro hardness tests. Through the strategies comprised in the field of Welding Metallurgy was carried out in a controlled way autogenous welding of the GTAW process in 12 samples of duplex stainless steel varying the protection gas, preheating temperature and type of current. Thus, using techniques of Characterization of Materials the samples were suitable to be performed micrographs and micro hardness tests. Next, justifications for the increase in point micro hardness were raised. The results obtained with the micrographs and tests of micro hardness brought another discussion on a subject, considering that some points further away from the Zone Cast gave values of micro hardness greater than closer, since it was expected that the values of micro hardness would be increasing from the Base Metal to the ZF. Thus, the hypotheses raised would be that precipitates were formed because of the chemical composition of the sample, as well as the time and temperature of heat treatment. Thus, chromium phases were the main focus of the study taking into account that it is the alloying element in greater quantity in the sample, phases such as α' (alpha line) and chromium nitride (Cr2N) were justifications for the increase of point microhardness in some regions of the samples. Therefore, with this study enables the broad knowledge that can be had when a duplex stainless-steel alloy is subjected to the welding process, since in certain applications the increase of micro hardness is extremely undesirable by the counterpart of making the material relatively more fragile, so it is necessary an extreme care in the sun of these materials since it may make it unusable.
Keywords
Stainless steel duplex UNS S31803, GTAW Welding, micro hardness
