Improved toughness and ductility in ferrite/acicular ferrite dual-phase steel through intercritical heat treatment

Shi, Lei; Zhang, Yan; Liu, Yongchang; Zhang, Cheng; Qiao, Zhixia; Ning, Baoqun; Li, Huijun

doi:10.1016/j.msea.2013.10.006

Cited by 64 publications

(32 citation statements)

References 23 publications

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“…Most of them focus on the effect of transformation products or/and heat treatment parameters on the toughness. [9][10][11][12][13][14][15][16][17] Few reports study the crystallography of the transformation products. 8,13) The discussion of the transformation products is seldom analyzed from a different angle.…”

Section: Microstructure and Micro Strain In The Cghaz Of 225cr-16w mentioning

confidence: 99%

Microstructure and Micro Strain in the CGHAZ of 2.25Cr-1.6W Steel after Intercritical Heat Treatment

2017

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Section: Microstructure and Micro Strain In The Cghaz Of 225cr-16w mentioning

confidence: 99%

Microstructure and Micro Strain in the CGHAZ of 2.25Cr-1.6W Steel after Intercritical Heat Treatment

2017

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“…The yield strength of the acicular ferrite has been reported to be in the range of 480-750 MPa [46][47][48][49]. The differences can be attributed to the steel composition as well as the testing procedures.…”

Section: Estimation Of the Acicular Ferrite Yield Strengthmentioning

confidence: 99%

Investigation of hydrogen assisted cracking in acicular ferrite using site-specific micro-fracture tests

Costin

Lavigne

Kotousov

et al. 2016

Materials Science and Engineering: A

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Hydrogen assisted cracking (HAC) is a common type of failure mechanism that can affect a wide range of metals and alloys. Experimental studies of HAC are cumbersome due to various intrinsic and extrinsic parameters and factors (associated with stress, hydrogen and the materials microstructure) contributing to the hydrogen crack kinetics. The microstructure of many materials consists of diverse constituents with characteristic features and mechanical properties which only occur in very small material volumes. The only way to differentiate the effect of these individual constituents on the hydrogen crack kinetics is to miniaturise the testing procedures. In this paper we present a new experimental approach to investigate hydrogen assisted crack growth in a microstructural constituent, i.e. acicular ferrite. For this purpose, sharply notched microcantilevers were fabricated with a Focus Ion Beam within this selected microscopic region. Acicular ferrite can be found in many ferrous alloys including ferritic weld metal and has specific features that control its intrinsic susceptibility to HAC. These features were characterised via Electron Backscatter Diffraction and the specimens were subsequently loaded under uncharged and hydrogen charged conditions with a nanoindenter. The outcomes of the testing, demonstrated that the threshold stress intensity factor, Kth, to initiate crack propagation in acicular ferrite ranges between 1.56 MPa m1/2 and 4.36 MPa m1/2. This range is significantly below the values of Kth reported for various ferrous alloys in standard macro-tests. This finding indicates that the mechanisms and resistance to HAC at micro-scale could be very different than at the macroscale as not all fracture toughening mechanisms may be activated at this scale level. Hydrogen assisted cracking (HAC) is a common type of failure mechanism that can affect a wide range of metals and alloys. Experimental studies of HAC are cumbersome due to various intrinsic and extrinsic parameters and factors (associated with stress, hydrogen and the materials microstructure) contributing to the hydrogen crack kinetics. The microstructure of many materials consists of diverse constituents with characteristic features and mechanical properties which only occur in very small material volumes. The only way to differentiate the effect of these individual constituents on the hydrogen crack kinetics is to miniaturise the testing procedures. In this paper we present a new experimental approach to investigate hydrogen assisted crack growth in a microstructural constituent, i.e. acicular ferrite. For this purpose, sharply notched micro-cantilevers were fabricated with a Focus Ion Beam within this selected microscopic region. Acicular ferrite can be found in many ferrous alloys including ferritic weld metal and has specific features that control its intrinsic susceptibility to HAC. These features were characterised via Electron Backscatter Diffraction and the specimens were subsequently loaded under uncharged and hydrogen charged con...

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“…Esse arranjo confere um efeito significativo nas propriedades e na conformabilidade, tornando esses aços uma das soluções disponíveis para atender à necessidade por materiais que apresentem ductilidade e resistência mecânica simultaneamente. A justificativa para este comportamento está embasada nas complexas interações entre os constituintes presentes na microestrutura dos avançados de alta resistência, que devem exibir variações significativas de dureza entre si [1]. Um dos principais representantes da classe de aços avançados de alta resistência são os aços bifásicos (dual phase), mais comumente utilizados na forma de chapas em aplicações automotivas para componentes de segurança [2].…”

Section: Introductionunclassified

Influência Da Temperatura Intercrítica Na Microestrutura E Nas Propriedades Mecânicas De Um Aço Bifásico

Magalhães¹,

Martins²,

Pinto³

et al. 2018

ABM Proceedings

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6Elaine Carballo Siqueira Corrêa 7 Resumo Nas últimas décadas a crescente demanda por carros mais seguros, econômicos e menos poluentes exigiram das montadoras, siderúrgicas e comunidade científica investimentos na pesquisa e no desenvolvimento de novos materiais, tais como os aços avançados de alta resistência. Dentro deste contexto, neste trabalho foi realizada a análise da microestrutura e das propriedades mecânicas de um aço bifásico na condição inicial e submetido a tratamentos térmicos com aquecimento na região intercrítica e resfriamento brusco. Foram analisadas a proporção dos constituintes na microestrutura e as propriedades mecânicas por meio de microscopia óptica e eletrônica de varredura, de difração de raios X, dureza e de tração. Observou-se, em geral, que o aumento da temperatura intercrítica levou a uma elevação da fração de martensita e, consequentemente, influenciou de forma a aumentar os valores de dureza, resistência mecânica e diminuir a ductilidade. Palavras-chave: Aço bifásico; Tratamento intercrítico; Microestrutura; Propriedades. INFLUENCE OF INTERCRITICAL TEMPERATURE IN THE MICROSTRUCTURE AND THE MECHANICAL PROPERTIES OF A DUAL PHASE STEEL AbstractIn recent decades the increasing demand for safer, economical and less polluting cars demanded of automakers, steelmakers and scientific community investments in research and development of new steels, such as advanced high strength steels. The aim of this work was the analysis of the microstructure and the mechanical behavior of a dual phase steel, in the initial condition and subjected to thermal processing with intercritical heating and quenching. The ferrite-martensite fraction in the material was evaluated by optical and scanning electron microscopy techniques and its influence in the mechanical properties was analyzed through hardness and tensile tests. It was observed that the increase of the intercritical temperature raised the fraction of martensite and thus led to an increase in hardness, yield strength and ultimate tensile strength and to a decrease in the elongation.

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Improved toughness and ductility in ferrite/acicular ferrite dual-phase steel through intercritical heat treatment

Cited by 64 publications

References 23 publications

Microstructure and Micro Strain in the CGHAZ of 2.25Cr-1.6W Steel after Intercritical Heat Treatment

Microstructure and Micro Strain in the CGHAZ of 2.25Cr-1.6W Steel after Intercritical Heat Treatment

Investigation of hydrogen assisted cracking in acicular ferrite using site-specific micro-fracture tests

Influência Da Temperatura Intercrítica Na Microestrutura E Nas Propriedades Mecânicas De Um Aço Bifásico

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