A submicron mild steel produced by simple warm deformation

Liu, Mingyuan; Bi, Sheng; Bi, Guangguo; Cao, H.; Cai, Xun; Song, Hongwei

doi:10.1016/s0921-5093(03)00406-4

Cited by 10 publications

(5 citation statements)

References 28 publications

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“…Ao nível macroscópico a principal heterogeneidade encontrada foi a presença de bandas de deformação. Pesquisas indicam que esta heterogeneidade apresenta uma maior densidade de defeitos cristalinos e ao mesmo tempo exibem maiores diferenças de orientação, atuando assim como locais preferenciais para a recristalização [6,7].…”

Section: Discussionunclassified

Estudo Da Evolução Microestrutural De Um Aço Microligado Submetido a Um Forjamento a Morno

Rodriguez¹,

Oliveira²,

Güiza³

2014

ABM Proceedings

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ResumoO desenvolvimento da indústria automobilística exige inovações na área de materiais de engenharia assim como de processos. A partir desta necessidade, as propriedades dos aços baixo e médio carbono podem ser melhoradas com a precipitação e refino de grão associado à adição de pequenas quantidades de elementos formadores de nitretos, carbonetos e carbonitretos. Aços baseados nestes princípios podem classificar-se como aços microligados, apresentando elevados níveis de resistência mecânica e tenacidade sem aumentos significativos nos custos de fabricação. No entanto, um dos métodos de obtenção de estruturas refinadas na indústria é mediante o processamento termomecânico com o propósito de se atingir uma microestrutura predeterminada. Assim o refino obtido é baseado no controle da cinética de nucleação e crescimento de grão. Neste trabalho foi estudado o efeito do forjamento a morno no refino de grão de um aço microligado. Inicialmente, as amostras foram aquecidas a 550°C, deformadas através de um processo de forjamento (40%, 60% e 80%) e resfriadas em água. Em seguida foram recozidas na região subcrítica por tempos variando de 1 min a 10 min e novamente resfriadas em água. A evolução microestrutural, assim como o comportamento mecânico deste aço, foram avaliados através de microscopia óptica, eletrônica (varredura e transmissão) e testes de dureza. O processo de forjamento mostrou-se eficaz na obtenção de uma microestrutura refinada associada a uma recristalização da ferrita. Palavras-chave: Aço microligado; Evolução microestrutural; Refino de grão; Trabalho a morno. STUDY OF THE MICROSTRUCTURAL EVOLUTION OF A WARM FORGED HSLA STEEL AbstractThe development of the automotive industry demands innovation both in the engineering materials, as well as in the conformation processes. Due to these new requirements, the properties of mild steels have been improved by grain refinement and precipitation hardening. The aforementioned mechanisms are activated by minute additions of carbide, nitride and carbonitride forming elements, such as Ti, Nb and V. The resulting steels are classified as High Strength Low Alloy (HSLA), combining high strength with low production cost. An additional way of inducing a grain refinement in these materials is through a thermomechanical process, specifically designed to obtain a predetermined structure. There, the grain size is reduced by a careful control of the nucleation and growth kinetics. In this research, the effect of warm forging in grain refinement of a HSLA steel is evaluated. Initially, some samples were heated to 550°C, following several degrees of deformation (40%, 60% and 80%) and quenching in water. Subsequently, they were subcritically annealed for a time ranging from 1 minutes to 10 minutes and, finally, cooled again in water. The microstructural evolution and the mechanical behaviour of these steel were evaluated through optical microscopy, scanning and transmission electron microscopy, and hardness testing. The warm forging process was effective in obtaining a refined m...

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Section: Discussionunclassified

Estudo Da Evolução Microestrutural De Um Aço Microligado Submetido a Um Forjamento a Morno

Rodriguez¹,

Oliveira²,

Güiza³

2014

ABM Proceedings

View full text Add to dashboard Cite

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“…It is very important to obtain both the ultra-fine microstructures and excellent properties of high carbon steels. The grain refinement can obviously improve the strength of steels as demonstrated by many earlier works, due to the ability of work hardening significantly decreasing and consequently sharply deteriorated plasticity [11][12][13]. So, it is difficult for high carbon steels to realize industrial production and application.…”

Section: Introductionmentioning

confidence: 97%

Mechanical Properties and Fracture Characteristics of Ultra-Microduplex Structure in High Carbon Steel

Lü

2011

AMR

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The ultra-microduplex structure was fabricated in the high carbon steel with a fully pearlitic structure after severe plastic deformation. The sizes of ferrite grains and cementite particles were about 0.4 μm and 0.1~0.2 μm, respectively. The mechanical properties of the ultra-microduplex structure were investigated using mini-tensile tests and the morphologies of fracture surfaces were observed with scanning electron microscopy (SEM). The results show that the tensile strength of the ultra-microduplex structure and the lamellar pearlite are almost at the same level, but after warm deformation, the yield strength was obviously increased and correspondingly, the elongation and the reduction of area were 19.2%, 32.1%, respectively, which are markedly higher than those of the lamellar pearlite. The tensile fracture of the ultra-microduplex structure is typical ductile fracture, however the fracture of original lamellar pearlite appears a mixture of cleavage fractures and quasi cleavage fractures.

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“…1 Therefore, ultrafine grained steels display a great potential to replace current high strength low alloyed steels. 2 The promise has led to extensive experimental [3][4][5][6][7][8][9][10] and theoretical 11,12 research activities in the field.…”

Section: Introductionmentioning

confidence: 99%

Modelling strength and ductility of ultrafine grained BCC and FCC alloys using irreversible thermodynamics

Huang

Rivera-Dı́az-del-Castillo

Bouaziz

et al. 2009

Materials Science and Technology

108

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A novel grain size dependent strain hardening model is derived from the theory of irreversible thermodynamics. The model yields the evolution of the dislocation densities in the grain interior and at the grain boundary, as well as their contributions to the flow stress. It is found that submicron grain sizes have a lower dislocation density in the grain interior, causing ductility to decrease greatly. The predicted stress–strain curve shapes, uniform elongation and ultimate tensile strength values for interstitial free steels (body centred cubic) and aluminium alloys (AA1100, face centred cubic) show good agreement with experimental observations.

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A submicron mild steel produced by simple warm deformation

Cited by 10 publications

References 28 publications

Estudo Da Evolução Microestrutural De Um Aço Microligado Submetido a Um Forjamento a Morno

Estudo Da Evolução Microestrutural De Um Aço Microligado Submetido a Um Forjamento a Morno

Mechanical Properties and Fracture Characteristics of Ultra-Microduplex Structure in High Carbon Steel

Modelling strength and ductility of ultrafine grained BCC and FCC alloys using irreversible thermodynamics

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