EFEITO DOS GASES DE PROTEÇÃO NA MICROESTRUTURA E NAS CINÉTICAS DE OXIDAÇÃO A ALTAS TEMPERATURAS AO AR DE JUNTAS SOLDADAS DE UM AÇO INOXIDÁVEL AUSTENÍTICO ATRAVÉS DO PROCESSO MIG/MAG
EFFECT OF SHIELDING GAS IN MICROSTRUCTURE AND KINECTICS OF HIGH TEMPERATURE OXIDATION IN AIR OF WELDED JOINTS OF AN AUSTENITIC STAINLESS STEEL THROUGH THE MIG/MAG PROCESS
Vicente, André de Albuquerque; Cabral, Débora Arruda; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto Soares
Resumo
Foram estudadas as microestruturas e as cinéticas de oxidação a altas temperaturas ao ar de quatro juntas soldadas de um aço inoxidável austenítico produzidas através do processo MIG/MAG com diferentes gases de proteção. Utilizou-se o metal de adição 22.12.HT e diferentes gases de proteção: 100% Ar, Ar + 2% CO2 , Ar +4% CO2 e Ar + 20% CO2 . Para cada mistura gasosa, foi soldado um corpo de prova. Estudou-se a variação das frações volumétricas de ferrita delta em função dos diferentes gases de proteção utilizados. Observou-se aumento no teor de carbono e consequente diminuição das frações volumétricas de ferrita delta, diminuições significativas nos teores de Cr, Si e Mn em relação à composição química do consumível de soldagem e consequente diminuição da resistência à oxidação a altas temperaturas ao ar dos metais depositados com gases de proteção com maiores concentrações de CO2 .
Palavras-chave
Abstract
The microstructures and the high temperature oxidation kinectics in air of four welded joints of austenitic stainless steel produced by the MIG/MAG process with different shielding gases were studied. Were used the welding wire 22.12. HT, and different shielding gases: 100% Ar, Ar + 2% CO2 , Ar +4% CO2 and Ar + 20% CO2 . For each gas mixture was welded a specimen. The variation of the volume fractions of delta ferrite according to the different shielding gases used, were studied. There was an increase in carbon content and decreasing of volume fraction of delta ferrite, a decrease in Cr, Si and Mn content when compared with the chemical composition of the welding wire decreasing the high temperature oxidation resistance in air of weld metals deposited with shielding gases with higher concentrations of CO2 .
Keywords
Referências
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