Probabilistic fracture toughness of a duplex stainless steel in the transition range

Faccoli, Michela; Roberti, Roberto

doi:10.1016/j.engfracmech.2012.09.027

Cited by 4 publications

(5 citation statements)

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“…Both approaches have experienced significant advancement over the years and have become commonly adopted in the structural integrity assessments for different applications. [8][9][10][11][12][13][14][15] The global model, as described in ASTM E-1921, 16 prescribes a three-parameter Weibull model to estimate the probability of cleavage fracture, supported by experimental evidence on 26 different ferritic steel materials. 17 The temperature dependence of the median fracture toughness follows the Master Curve, which depends on a reference temperature T 0 corresponding to a median fracture toughness of 100 MPa ffiffiffiffi m p .…”

Section: Introductionmentioning

confidence: 99%

“…ferritic steels, drives the development of statistical‐based treatment of cleavage failure, represented primarily by two broad categories of approaches, namely the global approach and the local approach. Both approaches have experienced significant advancement over the years and have become commonly adopted in the structural integrity assessments for different applications …”

Section: Introductionmentioning

confidence: 99%

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Effect of experimental sample size on local Weibull assessment of cleavage fracture for steel

Zhang

Qian

2016

Fatigue Fract Eng Mat Struct

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This paper examines the sample size of the experimental datasets in calibrating the Weibull parameters for the modified three‐parameter Weibull stress framework, so as to enhance the experimental strategy for cleavage assessment of ferritic steels based on a local approach. The present work generates a large number of random and independent subsets from the ‘Euro steel’ fracture toughness database for the calibration procedure. The calibration of the Weibull parameters utilizes a subset of high‐constraint specimens and a subset of low‐constraint specimens from the Euro steel database to resolve the uniqueness issue in the calibration procedure reported in previous studies. This investigation reveals strong dependence of the calibrated Weibull modulus on both the constraint differences between the high‐constraint subset and the low‐constraint subset and the size of the selected subsets. The scale fracture toughness value, however, does not exhibit significant dependence on the constraint difference between the two subsets of specimens. The confidence level of the scale fracture toughness, nevertheless, still exhibits strong dependence on the sample size of the experimental data.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of experimental sample size on local Weibull assessment of cleavage fracture for steel

Zhang

Qian

2016

Fatigue Fract Eng Mat Struct

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“…Diversos trabalhos [6], [9], [10] têm sido conduzidos em aços martensíticos, inclusive em aço duplex [11], com potencial aplicação na fabricação de VPR's. Neimitz [9], Lee et al [6] e…”

Section: Justificativa E Motivaçãounclassified

“…Neste contexto, a aplicabilidade da norma ASTM E1921 [5] é voltada especificamente para a classe de aços ferríticos, que incorporam aços bainíticos, bainíticos revenidos, martensíticos revenidos, ferríticos e perlíticos, com tensão de escoamento entre 275MPa e 825MPa [5]. Apesar destas restrições, diversos autores utilizaram a metodologia da CM para descrever o comportamento da tenacidade à fratura mediana avaliada na RTDF de diferentes tipos de aços (e.g., aços martensíticos [6], [9], [10], [12] e duplex [11]) e demonstraram relativo sucesso da MCM ao proporem alterações nos coeficientes da expressão que rege o comportamento exponencial da MCM.…”

Section: Justificativa E Motivaçãounclassified

Aplicação da metodologia da curva mestra à avaliação da temperatura de referência em um aço martensítico.

Gomes¹

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This work addresses an experimental investigation concerning the brittle fracture behavior of a martensitic steel using SE(B) specimens in a standardized configuration according to the ASTM E1921 standard. The purpose of this work is to assess Master Curve Methodology (MCM) applicability on evaluation reference temperature ( 0 ) derived from fracture toughness data measured in the ductile-to-brittle transition region (DBT) of a quenched martensitic steel USI AR 450 which according to ASTM E1921 is not applicable to martensitic steels only quenching. The work also presents a relatively straightforward procedure for the determination of new coefficients of the master curve for the sake of a better description of median fracture toughness change (expressed in terms of the elastic-plastic stress intensity factor ) according to the temperature in the DBT region and, hence, a more accurate 0 estimate. Fracture toughness tests, conducted at different temperatures in the DBT region using SE(B) specimens extracted in the TL orientation of a quenched martensitic steel plate, provide the fracture toughness data in terms of the J-integral at instability point, .Importantly, fracture toughness data of high strength martensitic steels tests described here provide a fracture toughness database for a material small explored in Master Curve methodology, which highlights its relevance in contributing to bank expansion and enrichment. Fracture toughness experimental data present a relatively significant dispersion and are well described by the Weibull probability distribution in its triparametric form. Notwithstanding that the Master Curve uses in its standard formulation provides a good description of fracture toughness dependence with temperature for the tested material ( vs. ), it is possible to afford a more accurate correlation from new coefficients proposed for the martensitic steel used in this study. Furthermore, a new value for the median fracture toughness closely related to the reference temperature is proposed.

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“…De acordo com a E1921, o valor limite estabelecido para é dado pela seguinte expressão = (3.19) em que é o ligamento remanescente ( = − ), é a tensão de escoamento medida na temperatura de ensaio e é o parâmetro adimensional cujo valor definido para o limite de deformação é igual a 30. Portanto, nos casos em que > ou em que ∆ > ∆ , o valor de 0 estimado para um = 2 via MMV com o modelo de censura é calculado a em que r corresponde ao número de valores válidos segundo critérios estabelecidos na E1921, ou seja, r = − c em que c refere-se ao número de dados censurados.Devido ao fato de inúmeros trabalhos[253][254][255] reportarem os valores de 0 e por meio da linearização da f.d.a. de Weibull, Eq.…”

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Investigação experimental dos efeitos de geometria e de carregamento sobre a distribuição dos valores de tenacidade à fratura por clivagem medidos na região de transição dúctil-frágil de um aço estrutural ferrítico.

Barbosa¹

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0 , a partir da metodologia da curva mestra também fornece um suporte adicional para o uso de corpos de prova SE(B) não padronizados como uma alternativa geométrica nos procedimentos rotineiros de avaliação de tenacidade à fratura, incluindo o uso de corpos de prova de pequenas dimensões nas medições de tenacidade quando a disponibilidade limitada de material e a capacidade de carregamento da máquina são as principais preocupações.Palavras-chave: fratura por clivagem, corpo de prova SE(B) não padronizado, corpo de prova PCVN não padronizado, efeitos de restrição, temperatura de referência, curva mestra ABSTRACT This work addresses a numerical-experimental investigation on the cleavage fracture behavior of an ASTM A572 Grade 50 high strength, low alloy structural steel using standard and nonstandard SE(B) specimens, including a non-standard PCVN configuration. The main purpose of this study is to contribute to the development of a fracture toughness test procedure applicable to bend geometries with varying specimen span over width ratio ( / ) and loaded under 3-point and 4-point flexural configuration. The secondary purpose, but none the less important, is to investigate the effects of geometry and loading mode on experimentally measured fracture toughness data distributions and implications for the characterization of the temperature dependence of toughness based on the Master Curve methodology. Based on these purposes, a large new set of plastic -factors applicable to these non-standard bend geometries which serve to estimate the experimentally measured toughness values in terms of load-displacement records, including the -integral and the crack tip opening displacement ( ), is provided. In order to facilitate contact with other test protocols, a new set of rotational factors, , to determine the based on the plastic hinge model is also described. Fracture toughness testing conducted on various bend geometries with varying specimen span ( / ) extracted in the T-L orientation from an A572 Grade 50 steel plate provides the cleavage fracture resistance data in terms of the -integral at cleavage instability, . The experimental results show a potential effect of specimen geometry and loading mode on -values which can help mitigating the effects of constraint loss often observed in smaller fracture specimens. An exploratory application to determine the reference temperature, 0 , derived from the Master Curve methodology also provides additional support for using nonstandard bend specimens as an alternative specimen geometry in routine fracture assessments, including the use of small-scale fracture specimens to measure fracture toughness properties when limited material availability and test machine capacity are of major concern are of major concern.

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Probabilistic fracture toughness of a duplex stainless steel in the transition range

Cited by 4 publications

References 8 publications

Effect of experimental sample size on local Weibull assessment of cleavage fracture for steel

Effect of experimental sample size on local Weibull assessment of cleavage fracture for steel

Aplicação da metodologia da curva mestra à avaliação da temperatura de referência em um aço martensítico.

Investigação experimental dos efeitos de geometria e de carregamento sobre a distribuição dos valores de tenacidade à fratura por clivagem medidos na região de transição dúctil-frágil de um aço estrutural ferrítico.

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