Microstructure and mechanical properties of a microalloyed steel after thermal treatments

Cota, André Barros; Oliveira, Fernando Lucas Gonçalves e; Barbosa, A. L. R.; Lacerda, Cássio Antônio Mendes; Araújo, Fernando Gabriel da Silva

doi:10.1590/s1516-14392003000200002

Cited by 19 publications

(6 citation statements)

References 4 publications

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“…This seems consistent with the design basis for these steels, since the volume fraction of martensite mainly determines the strength and hardness of DP steels. 2,23) As well, this result agrees with previous findings showing that the volume fraction of martensite in the DP steels determined the reduction of ultimate tensile strength when the HAZ was simulated in DP steels using a Gleeble thermal simulator. 15) …”

Section: Effects Of Martensite Content On Maximum Haz Softeningsupporting

confidence: 91%

Effects of Heat Input and Martensite on HAZ Softening in Laser Welding of Dual Phase Steels

Xia¹,

Biro²,

Tian³

et al. 2008

ISIJ Int.

202

105

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Laser welds were made in three dual-phase (DP) alloys with ultimate tensile strengths ranging from 450-980 MPa and varying microstructures to investigate effects of heat input on heat affected zone (HAZ) softening. To compare the total heat transferred into the HAZ of all the welds, heat input was normalized using the Rosenthal Equation. It was found that HAZ softening experienced in a DP steel was a function of both martensite content and heat input. Maximum HAZ softening was proportional to the martensite content, and the heat input controlled the completion of softening. Material softening was normalized by martensite content, which showed that the contribution of martensite to material hardness from the three materials is the same; however the materials had different transformation kinetics.

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Section: Effects Of Martensite Content On Maximum Haz Softeningsupporting

confidence: 91%

Effects of Heat Input and Martensite on HAZ Softening in Laser Welding of Dual Phase Steels

Xia¹,

Biro²,

Tian³

et al. 2008

ISIJ Int.

202

105

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“…Interest has increased in the use of microalloyed forging steels in place of quenched-and-tempered steels to realise cost savings [1]. Microalloyed forging steels have been developed over the past several years and are increasingly applied in a variety of large-scale structures, engine, transmission, suspension and driveline components such as the flange, gears, springs, crankshafts, connecting rods, axles and shaft [2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effects of tungsten addition and heat treatment conditions on microstructure and mechanical properties of microalloyed forging steels

Zhao

Jiang

Lee

2013

Materials Science and Engineering: A

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In the present work, the effects of tungsten (W) addition and heat treatment conditions on the microstructure, impact toughness and tensile properties of microalloyed forging steels were studied. Four kinds of microalloyed forging steels were produced by varying W additions (0, 0.5, 1 and 2 wt%). Heat treatment was carried out at temperatures ranging from 840 to 950 °C followed by air and furnace cooling. Mechanical tests were used to evaluate the room temperature Charpy impact and tensile properties. The resulting microstructures were analysed via optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the microstructure and mechanical properties of the microalloyed forging steels are closely related to the W content. Correct selection of heat treatment temperature and cooling method is very important to enhance the mechanical properties. The optimum heat treatment temperatures obtained in this study are 920, 900, 880 and 860 °C for the steels with 0%, 0.5%, 1% and 2% W, respectively. Both the impact toughness and tensile properties of the microalloyed forging steels have been significantly enhanced after heat treatment at the optimum temperatures followed by air cooling. AbstractIn the present work, the effects of tungsten (W) addition and heat treatment conditions on the microstructure, impact toughness and tensile properties of microalloyed forging steels were studied. Four kinds of microalloyed forging steels were produced by varying W additions (0, 0.5, 1 and 2 wt.%). Annealing treatment was carried out at temperatures ranging from 840 to 950℃ followed by air and furnace cooling. Mechanical tests were used to evaluate the room temperature Charpy impact and tensile properties. The resulting microstructures were analysed via optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results show that the addition of W plays an important role in increasing the strength and decreasing the toughness of the studied steels. Correct selection of annealing temperature and cooling method is very important to enhance the mechanical properties. The optimum annealing temperatures obtained in this study are 920, 900, 880 and 860℃ for the steels with 0, 0.5, 1 and 2% W, respectively. Both the impact toughness and tensile properties of the microalloyed forging steels have been significantly enhanced after heat treatment at the optimum temperatures followed by air cooling.

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“…As amostras utilizadas no estudo da cinética de revenimento foram submetidas a dois diferentes tratamentos de austenitização e têmpera: o aço I-Nb foi austenitizado a 1100°C por 30min e temperado em água+gelo, com o objetivo de se obter o tamanho de grão austenítico de 100µm [5] ; o aço I foi austenitizado 1075ºC por 30min e temperado em água+gelo, com o objetivo de se obter uma microestrutura com o mesmo tamanho de grão austenítico do aço I-Nb, 100µm.…”

Section: Procedimento Experimentalunclassified

“…Com relação ao elemento de liga Nb, existem poucos relatos de sua influência nas propriedades mecânicas de chapas de aços submetidas ao tratamento térmico de têmpera e revenimento [5] . Portanto faz-se necessário um estudo da influência do Nb sobre as propriedades mecânicas de chapas de aços revenidos.…”

Section: Introductionunclassified

Efeito do Nb na cinética de revenimento de aços de baixo carbono

Hermenegildo

Cota

2007

Rem: Rev. Esc. Minas

Self Cite

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The effect of temperature and time on tempering kinetics was studied by using a low carbon steel microalloyed with Nb (0,031) ResumoOs efeitos da temperatura e do tempo sobre a cinéti-ca de revenimento foram estudados, utilizando chapas de um aço baixo carbono e microligado com Nb e de outro aço com composição química similar, porém sem Nb. A lei de cinética de revenimento foi estudada pela equação de Johnson, Mehl e Avrami, a partir da variação da dureza Vickers das amostras revenidas com a temperatura e com o tempo de revenimento para os dois aços. Para o aço sem Nb, verificou-se que a dureza praticamente não variou com o tempo de revenimento, para a temperatura de revenimento de 600°C, e que a dureza tende a saturar para altos tempos de revenimento, para as diferentes temperaturas de revenimento utilizadas. Para o aço com Nb, observou-se uma maior resistência ao revenimento para as temperaturas de revenimento de 500 e 600°C, associada à precipitação de partículas muito finas de carbonetos de Nb dispersos na ferrita. A energia de ativação, para o revenimento, para o aço sem Nb, é de 130kJ/mol e podese inferir que o mecanismo que limita a cinética de revenimento, é a difusão intersticial do carbono na ferrita. Para o aço com Nb, a energia de ativação, para o revenimento é de 180kJ/mol e pode-se inferir que o mecanismo que limita a cinética de revenimento é a difusão do Nb na ferrita.Palavras-chave: Cinética de revenimento, nióbio, aço baixo carbono.

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Microstructure and mechanical properties of a microalloyed steel after thermal treatments

Cited by 19 publications

References 4 publications

Effects of Heat Input and Martensite on HAZ Softening in Laser Welding of Dual Phase Steels

Effects of Heat Input and Martensite on HAZ Softening in Laser Welding of Dual Phase Steels

Effects of tungsten addition and heat treatment conditions on microstructure and mechanical properties of microalloyed forging steels

Efeito do Nb na cinética de revenimento de aços de baixo carbono

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