Austenitic solidification mode in austenitic stainless steel welds

Takalo, T.; Suutala, N.; Moisio, T.

doi:10.1007/bf02811663

Cited by 162 publications

(70 citation statements)

References 5 publications

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“…This expected behavior can be understood using a schematic of the Fe-Ni-Cr pseudo binary, figure 1. In a casting or conventional weld, Heat +12, with Creqmieq=1.55 (approximated by G~figure 1), should solidify as primary ferrite with secondary solidification of austenite and contain several percent retained ferrite [14][15][16][17]. However, the faster cooling conditions of laser welding were s tiigurel.…”

Section: Methodsmentioning

confidence: 99%

Microstructures of Laser Deposited 304L Austenitic Stainless Steel

2000

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BSTRACT $~qjLaser deposits fabricated from two different compositions of 304L stainless steel powder were characterized to determine the nature of the solidification and solid state transformations. One of the goals of this work was to determine to what extent novel microstructure consisting of single-phase austenite could be achieved with the thermal conditions of the LENS process. Although ferrite-free deposits were not obtained, structures with very low ferrite content were achieved. It appeared that, with slight changes in alloy composition, this goal could be met via two different solidification and transformation mechanisms.

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Section: Methodsmentioning

confidence: 99%

Microstructures of Laser Deposited 304L Austenitic Stainless Steel

2000

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“…Afim de prever o modo de solidificação dos aços inoxidáveis através das expressões de cromo e niquel equivalentes propostas por O. Hammar e Svensson [6,10], Suutala e Moisio [11] rearranjaram os resultados obtidos em diversos trabalhos [5,7,[12][13][14][15][16] com diferentes velocidades de solidificação. Quando a relação Creq/Nieq <1,5 a solidificação poderá ser austenítica (modo I) ou austenítica-ferrítica (modo II).…”

Section: Efeito Dos Gases De Proteção Na Microestrutura E Nas Cinéticunclassified

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

Vicente¹,

Cabral²,

Espinosa³

et al. 2017

Tecnologia Em Metalurgia Materiais E Mineração

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ResumoForam 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% CO 2 , Ar +4% CO 2 e Ar + 20% CO 2 . 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 CO 2 . Palavras-chave: Aços inoxidáveis; Gases de proteção; Fração volumétrica; Oxidação a altas temperaturas; 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 AbstractThe 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% CO 2 , Ar +4% CO 2 and Ar + 20% CO 2 . 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 CO 2 . Keywords: Stainless steels; Shielding gases; Volume fraction; High temperature oxidation; MIG/MAG. INTRODUÇÃOAlém do ferro, cromo e níquel, os aços inoxidáveis têm em sua composição outros elementos químicos que podem estabilizar a ferrita e a austenita. Levando em conta os seus efeitos ferritizantes e austenitizantes, Schaeffler [1] agrupou estes elementos em duas expressões denominadas de cromo equivalente e níquel equivalente, respectivamente e propôs um diagrama que é apresentado na Figura 1. O diagrama de Schaeffler não é um diagrama de equilíbrio. Ele foi determinado experimentalmente com o objetivo de prever-se o teor de ferrita delta em soldas de aços inoxidáveis.Além das expressões de cromo equivalente (Creq=%Cr+%Mo+1,5%Si+0,5%Nb) e de níquel

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“…Due to the harsh working environment and particularity, ITER headquarters has a high demand for low-temperature impact toughness of 316LN welded metal [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Pulse Current on Microstructure and Hardness of 316LN Weld Metal

He¹,

Dai²,

Gu³

et al. 2018

Proceedings of the 2017 3rd International Forum on Energy, Environment Science and Materials (IFEESM 2017)

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Abstract. 316LN austenitic stainless steel (ASS) has been used as a magnetic support structure for ITER. Pulse current as a new materials processing method, has many remarkable advantages. In this paper, the pulse current was used to treat the 316LN ASS welded metal welded by narrow gap MAG welding. The influence of different pulse current parameters on microstructures and microhardness of 316LN austenitic stainless steel weld metal was investigated. It was found that the microstructure of 316LN weld metal had a transitional trend from columnar sub-grains to equiaxed grains when the pulse current is increased to 700A. As the pulse current gradually increasing, the microhardness of weld metal first showed a constant trend, then decrease, and finally increase; with the increase of processing time, the microhardness of weld metal increased; with the increase of pressure, the microhardness of weld metal increased too.

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Austenitic solidification mode in austenitic stainless steel welds

Cited by 162 publications

References 5 publications

Microstructures of Laser Deposited 304L Austenitic Stainless Steel

Microstructures of Laser Deposited 304L Austenitic Stainless Steel

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 Pulse Current on Microstructure and Hardness of 316LN Weld Metal

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