Fatigue hardening/softening behaviour investigated through Vickers microhardness measurement during high-cycle fatigue

Ye, Duyi; Tong, Xiaoyan; Yao, Leijiang; Yin, Xiaoxia

doi:10.1016/s0254-0584(98)00135-7

Cited by 20 publications

(13 citation statements)

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“…Indeed, relationships between hardness and both tensile and yield strength can be found in the literature. More recently, different authors have investigated relationships between cyclic behaviour and hardness change during fatigue [13][14][15]. In addition, fatigue behav-iour and even fatigue damage were evaluated using hardness measurements [15,16].…”

Section: Discussionmentioning

confidence: 99%

“…More recently, different authors have investigated relationships between cyclic behaviour and hardness change during fatigue [13][14][15]. In addition, fatigue behav-iour and even fatigue damage were evaluated using hardness measurements [15,16]. When quenched and tempered steels are subjected to strain controlled fatigue, a sharp cyclic softening is obtained as shown in Figs.…”

Section: Discussionmentioning

confidence: 99%

“…This measurement of the resistance to penetration is often linked to both yield and tensile strength with empirical relationships. Recently, several authors investigated the relationship between cyclic behaviour and hardness measured after fatigue [13][14][15]. This led to the conclusion that hardness measurement can be a relevant test to evaluate cyclic hardening or softening and even fatigue damage.…”

Section: Introductionmentioning

confidence: 99%

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Ageing effect on cyclic plasticity of a tempered martensitic steel

Zhang

Delagnes

Bernhart

2007

International Journal of Fatigue

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Specific isothermal cyclic deformation tests were carried out on a tempered martensitic steel 55NiCrMoV7 at four hardness levels in the temperature range 20-600 °C. The cyclic stress response generally shows an initial exponential softening for the first few cycles, followed by a gradual softening without saturation. The influences of initial hardness obtained after tempering, temperature, strain rate and ageing on cyclic plasticity are discussed by means of hardness measurements and equivalent ageing experiments. Compared to hardness measured after ageing without fatigue loading, hardness dramatically decreases when the specimen is simultaneously subjected to ageing and fatigue at elevated temperature. Cyclic softening intensity increases with testing temperature from 300 to 600 °C, but the maximal softening intensity occurs at room temperature. This is inconsistent with hardness measurements performed on the specimen after a fatigue test conducted at room temperature. The final discussion focuses on the mechanisms involved in the softening of martensitic steels to explain the last result.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ageing effect on cyclic plasticity of a tempered martensitic steel

Zhang

Delagnes

Bernhart

2007

International Journal of Fatigue

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“…With increasing plastic strain, the persistent slip bands were formed on the surface of the specimen to increase a roughness on the surface. The hardness increased due to work-hardening caused by increasing dislocation density and tangling of dis- locations [13,19]. Therefore, changes in the surface roughness and the hardness with strain were similar.…”

Section: Change In Ultrasonic Parameters Measured Off-line With Deformentioning

confidence: 92%

Real-time ultrasonic measurement during tensile testing of aluminum alloys

Min

Katô

Narisawa

et al. 2005

Materials Science and Engineering: A

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“…A literatura técnica e científica apresenta inúmeros trabalhos que fazem uso da técnica de microdureza, como ferramenta auxiliar em estudos aprofundados a respeito de caracterização de fases diversas, profundidade e eficiência de tratamentos térmicos superficiais, cinética de recristalização e de transformações de fases, identificação e caracterização de precipitados em ligas metálicas, caracterização de juntas soldadas, propagação de trincas por fadiga, tenacidade à fratura entre outros [5][6][7][8][9][10][11][12][13][14]. Um problema característico desta técnica é a influência de diversos fatores operacionais sobre a representatividade e reprodutibilidade dos resultados.…”

Section: Introductionunclassified

Desenvolvimento De Um Software De Análise De Imagens Para Automação Dos Procedimentos De Determinação De Microdureza Vickers

Coelho¹,

Moreira²,

Faria³

et al. 2014

ABM Proceedings

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ResumoO ensaio mecânico de microdureza Vickers consiste em aplicar uma força sobre a superfície de materiais e induzir uma deformação plástica localizada. Por meio da análise das dimensões da impressão gerada em função da carga aplicada, determina-se um parâmetro denominado microdureza. Este ensaio tem sido muito difundido para o desenvolvimento de pesquisas e para análises de controle de qualidade devido às suas diversas aplicações, que incluem a determinação de durezas de fases específicas, a identificação da existência de precipitados, o controle de qualidade de juntas soldadas, a caracterização de tratamentos térmicos superficiais, entre outras. Entretanto, um problema associado a esta técnica é a influência do operador sobre as medidas realizadas. Com o objetivo de eliminar esta dispersão de resultados, este trabalho se propôs a desenvolver um software que, por meio de análise de imagens, identifica automaticamente as impressões na superfície das amostras e determina as suas dimensões. O software foi desenvolvido na linguagem C++, fazendo uso da biblioteca multiplataforma OpenCV. Os dados utilizados para a sua calibração foram provenientes de ensaios em amostras de aços, ferros fundidos, ligas de alumínio e de cobre. Os resultados comprovaram a capacidade do software de realizar medições com boa precisão e excelente reprodutibilidade, mas há a necessidade de melhorar os critérios de identificação das impressões, aplicando, por exemplo, técnicas de aprendizado de máquina. Palavras-chave: Microdureza vickers; Visão computacional; Medição automática de microdureza; OpenCV. DEVELOPMENT OF IMAGE ANALYSIS SOFTWARE APPLIED TO AUTOMATION OF VICKERS MICROHARDNESS MEASUREMENTS AbstractVickers microhardness mechanical test consist to apply a force on a material surface and to promote a located plastic deformation. Analyzing the superficial impression dimensions as the applied load function, it is possible to determine a quantitative parameter named microhardness. This test has been intensely used in scientific and technologic developments which aim to propose new materials and processes or just to control the produced material quality. The most part of studies with microhardness is focused in metals, and the technique has been useful to measure specific phases hardness, to identify precipitate presence, to control welded joints quality, to characterize different kinds of heat treatments and others. However, the machine operator influences are a common but undesirable problem associated with this method. Aiming to eliminate results dispersion due to machine operator actions, this study proposed to develop a software that using image analysis, automatically identify impressions on sample surfaces and measure their dimensions. The software was built in C++ language, using the multiplataform library OpenCV. The software calibration was done using experimental data, collected from microhardness tests in different kind of materials, as steel, cast iron, aluminum and copper alloys. Obtained results proved the software capabil...

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Fatigue hardening/softening behaviour investigated through Vickers microhardness measurement during high-cycle fatigue

Cited by 20 publications

References 4 publications

Ageing effect on cyclic plasticity of a tempered martensitic steel

Ageing effect on cyclic plasticity of a tempered martensitic steel

Real-time ultrasonic measurement during tensile testing of aluminum alloys

Desenvolvimento De Um Software De Análise De Imagens Para Automação Dos Procedimentos De Determinação De Microdureza Vickers

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