The evaluation of material fracture mechanic properties has had an increasing need, especially in the oil and gas industries. This scenario requires quality assurance of fracture toughness tests. This article describes the activities carried out when implementing the Quality Management System (QMS) for the fracture toughness tests at the Physical Metallurgy Laboratory (LAMEF) in the Federal University of Rio Grande do Sul (UFRGS), Brazil, in order to achieve the management and technical requirements of ISO/IEC 17025. Since LAMEF was previously accredited in performing other tests, most of the adequacy was related to the technical requirements of the ISO/IEC 17025 standard. After performing the required adjustments and after an external audit, the Brazilian Institute of Metrology, Quality and Technology (Inmetro) accredited LAMEF to the fracture toughness tests. The accreditation of these tests is unprecedented in Brazil, and we expect this work to encourage other Brazilian and world laboratories to seek the implementation and accreditation of QMS for fracture mechanics tests.
Abstract. In order to ensure the quality assurance and comply with standard requirements, an intralaboratory study has been performed for impact Charpy tests, involving two operators. The results based on ANOVA (Analysis of Variance) and Normalized Error statistical techniques pointed out that the execution of the tests is appropriate, because the implementation of quality assurance methods showed acceptable results.
Resumo A grande maioria dos materiais, quando em uso no dia a dia, está sujeito a esforços ou cargas. Sendo assim, é necessário conhecer as características dos materiais para projetar o componente de tal maneira que a deformação resultante não seja excessiva, ocasionando a fratura. Neste estudo foram realizados ensaios de tração em um aço SAE 4340 com diferentes velocidades de ensaio, selecionadas com base em referências normativas (ASTM E8/E8M e ISO 6892-1) e também na literatura e, assim, estabelecidas como 0,45 mm/min, 12,5 mm/min, 100 mm/min e 500 mm/min. Os testes mostraram que a velocidade do ensaio de tração exerce influência significativa no comportamento da curva tensão-deformação e, consequentemente, nas propriedades do material. Palavras chave: Ensaio de tração; Velocidade de deformação; Propriedades; Aço SAE 4340. THE EFFECT OF STRAIN RATE ON TENSILE TEST IN A STEEL SAE 4340
The Brinell hardness test is one of the most used mechanical tests in the industry to assure the quality of metallurgical processes. Based on the measured values, it is necessary to describe the measurement uncertainty values associated with the mathematical method used. Thus, measurement uncertainty values describe the reliability of the experimental results. The calculation of measurement uncertainty can be performed in several ways, and the method described by ISO/GUM is the most used by ISO/IEC 17025 accredited laboratories. The main objective of this work is to compare measurement uncertainty values based on different sources of uncertainty used in the measurement uncertainty evaluation for two Brazilian laboratories accredited by Cgcre/INMETRO. In addition, uncertainty values obtained by the GUM method and by the Monte Carlo method were compared. The results show that there is no great variation in the measurement uncertainty values as a function of the mathematical method used.
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