Study on microstructures and properties of carbide-free and carbide-bearing bainitic steels

Long, Xiaoyan; Zhang, Fucheng; Yang, Zhinan; Lv, Bo

doi:10.1016/j.msea.2017.12.108

Cited by 49 publications

(29 citation statements)

References 38 publications

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“…According to Georgiyev et al [4], the highest performance with respect to crack resistance in medium-carbon steels of similar strength is obtained from carbide-free lower bainite microstructures. The main outcome of a recent study published by Long et al [5] also attests to the improved performance of the carbide-free lower bainitic steels when compared with carbide-bearing lower bainitic steels in a low-cycle fatigue regime.…”

Section: Introductionmentioning

confidence: 81%

Comparative Study of the Uniaxial Cyclic Behaviour of Carbide-Bearing and Carbide-Free Bainitic Steels

Branco

Berto

Zhang

et al. 2018

Metals

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Bainitic steels play an important role in the modern automotive and rail industries because of their balanced properties. Understanding the relationship between the bainitic microstructure features and the fatigue performance is a fundamental ingredient in developing safer and durable products. However, so far this relationship is not sufficiently clear. Therefore, there is the need to strengthen the knowledge within this field. The present paper aims at comparing the uniaxial cyclic behaviour of carbide-bearing and carbide-free bainitic steels. To meet this goal, fully-reversed strain-controlled tests at various strain amplitudes were performed. After the final failure, fracture surfaces were observed by transmission electron microscopy to relate the bainitic morphology to the fatigue performance. The main findings of this work show that the carbide-free lower bainite has superior fatigue performance compared to the carbide-bearing lower bainite. This is explained by the presence of stable carbides and thick bainite ferrite plates.

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Section: Introductionmentioning

confidence: 81%

Comparative Study of the Uniaxial Cyclic Behaviour of Carbide-Bearing and Carbide-Free Bainitic Steels

Branco

Berto

Zhang

et al. 2018

Metals

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“…However, the weldability of the steel will be poor when the carbon content is about 0.8%, and it is easy to produce cold cracks in welding, which seriously hinders its popularization and application (Fang et al, 2013). On the other hand, the bainite structure is a metastable structure (Long et al, 2018). In accordance with this characteristic, the bainite structure can be transformed by adopting proper tempering treatment (Wang et al, 2019), thereby improving its mechanical and welding performances.…”

Section: Introductionmentioning

confidence: 99%

Study on Corrosion Resistance and Welding Properties of High Strength, Tough Bainite Steel CB10

Cheng

Zhou

et al. 2019

Front. Mater.

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In order to achieve high strength and toughness in bainite steel, the authors carried out a study on their self-developed CB10 steel. The CB10 steel was heat-treated at different tempering temperatures to control its microstructure and mechanical capabilities, and, further, changes in its structure were explored. The results showed that bainite, ferrite, and M/A islands could be engendered when CB10 steel was tempered at 250 • C, 450 • C, 600 • C, and 670 • C, respectively. With an increase in tempering temperature, lath-type bainite began to merge and coarsen obviously, and polygonal ferrite appeared. When the tempering temperature was above 600 • C, recovery and recrystallization occurred in some regions. In particular, the mechanical properties of CB10 steel were best at a 450 • C tempering temperature; among them, its tensile strength was 632 MPa, its yield strength was 487 MPa, elongation was 25%, and the Charpy absorbed energy was >140 J. Furthermore, the anti-hydrogen-induced cracking performance and weldability of CB10 steel were tested. The results indicated that there were no cracks on the surface of the sample, indicating that it has excellent anti-hydrogen-induced cracking performance and weldability. Moreover, the maximum hardness of the heat-affected zone was 231 Hv, the maximum Charpy absorbed energy was 285.0 J, and the fracture morphology was in all cases ductile fracture when the impact temperature was above −60 • C.

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“…Entretanto, como já mencionado anteriormente, proporções, morfologias, grau de refinamento da microestrutura, entre outros fatores, alteram consideravelmente as propriedades mecânicas. Fonte: [158] Um estudo mais recente entre dois aços diferentes quanto ao teor de Si, apresentou diferenças nas propriedades mecânicas, em função das microestruturas obtidas em cada caso (CFB na amostra com adição de silício e carbonetos esféricos na amostra sem o elemento) [167]. A explicação é dada a partir do esquema montado na Figura 52.…”

Section: Propriedades Mecânicasunclassified

“…Fonte: [167] Observa-se que a transformação martensítica da AR, acompanhada por uma expansão de volume e absorção de energia, pode inibir a propagação de uma trinca por fadiga, aumentando a tenacidade e prolongando a vida em fadiga no aço formado por CFB. Além disso, Fonte: Próprio autor.…”

Section: Figura 52 -Efeito Das Fases Nas Propriedades Mecânicas De Umunclassified

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Têmpera e partição de aço baixa liga com pré-microestrutura bainítica

Mendonça¹

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Os aços temperados e particionados têm despertado interesse no que se refere ao equílibro entre resistência e ductilidade, comumente representado pelo índice PSE (produto da resistência pelo alongamento). A estabilização da austenita retida em baixas temperaturas pode provocar o fenômeno da plasticidade induzida por transformação (efeito TRIP). Com o surgimento da têmpera e partição (T&P), diversas variações desse tratamento têm sido propostas. Dentre elas, o efeito da pré-microestrutura tem se mostrado muito importante na melhoria das propriedades mecânicas. Dessa forma, no presente trabalho foi proposto um processo inédito de têmpera e partição a partir de pré-microestruturas bainíticas. O intuito dessa abordagem foi verificar, a partir de diferentes proporções e morfologias bainíticas, os diferentes níveis de estabilização da austenita retida. Além disso, a obtenção de microestruturas multifásicas têm sido relatada na literatura com boas características mecânicas. A caracterização microestrutural foi feita por meio de microscopias ópticas e eletrônica de varredura, e ensaios de dureza, tração e impacto. Os resultados encontrados foram de encontro aos relatados na literatura, indicando que uma homogênea distribuição de finos carbonetos pode gerar melhores resultados do que a tão aclamada austenita retida. Foram encontrados valores de limite de resistência à tração de 1.081 MPa com alongamento total de 23%, gerando valores de PSE de 24.8 GPa . % com resistência ao impacto de 62 J/cm². Os tratamentos térmicos realizados também mostraram-se mais eficazes que os tradicionais tratamentos de austêmpera e têmpera com revenimento para competir com os aços da nova geração. Palavras-chave: Bainita, Austenita retida, Têmpera e partição, Efeito TRIP, Prémicroestrutura. ABSTRACT MENDONÇA, R.R. Quenching and partitioning of a low alloy steel with bainitic prior microstructure. 2019. 175p. Tese (Doutorado) -Escola de Engenharia de São Carlos, Universidade de São Paulo, São Carlos, 2019. Quenched and partitioned (Q&P) steels have been of great interest to researchers due to its balance between strength and ductility, usually represented by the product of strength and elongation (PSE) index. Retained austenite, when stabilized at room temperature, can promote the transformation induced plasticity phenomenon (TRIP) effect. With the advent of quenching and partition heat treatment many variations to this process were made. Among them, the influence of prior microstructures has been shown to be very important in improving the mechanical properties. In this way, this research proposed a new processing route for the Q&P starting from a bainitic microstructure. The intention of this approach was to verify, by means of different bainite proportions, different levels of retained austenite stabilization. In addition, there have been positive results in obtaining of multiphase microstructures. Microstructural characterization was evaluated by both optical microscopy and scanning electron microscopy while mechanical properties were analyz...

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Study on microstructures and properties of carbide-free and carbide-bearing bainitic steels

Cited by 49 publications

References 38 publications

Comparative Study of the Uniaxial Cyclic Behaviour of Carbide-Bearing and Carbide-Free Bainitic Steels

Comparative Study of the Uniaxial Cyclic Behaviour of Carbide-Bearing and Carbide-Free Bainitic Steels

Study on Corrosion Resistance and Welding Properties of High Strength, Tough Bainite Steel CB10

Têmpera e partição de aço baixa liga com pré-microestrutura bainítica

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