Development of Methods for Measuring the Characteristics of Steel Ductility During Static Tensile Testing

The article is devoted to the development of methods for measuring the characteristics of the steel ductility during static tensile testing – relative elongation and relative contraction after rupture. The objectives of the work were to analyze the uncertainty budgets of measurements of relative elongation and relative contraction after rupture determined during static tensile testing, optimize the measurement parameters associated with sample preparation using methodological factors, assess the contributions to the measurement uncertainty budgets during the development of measurement methods, and develop methods for measuring relative elongation and relative contraction after rupture intended to assess the accuracy of measurement results obtained using standard methods for measuring the same quantities according to GOST 1497–2023 «Metals. Tensile test methods». In the course of the work, theoretical and experimental studies were carried out to compile uncertainty budgets for measurements of relative elongation and relative contraction after rupture, indicating the identified sources of uncertainty. Metrological characteristics of measurement methods were calculated. As a result of the study, two methods for measuring the characteristics of steel ductility using a video measuring microscope were developed and certified, providing a margin of accuracy compared to the standardized measurement method according to GOST 1497–2023, intended for testing for the purpose of approving the type of reference materials.