Engineering of reference materials for providing traceability of measurements of mechanical stresses by acoustic type of nondestructive check

Abstract

The article presents the investigation of a certified reference material (CRM) of the steels mechanical properties. At present traceability of measurement results of mechanical stresses is ensured to the standard of time, but not mechanical stresses, and a metrological approach to ensuring the uniformity of measurements of mechanical stresses requires the development of a basis for comparison.The aim of the work was the characterization and certification of standard samples of a special form, traceable to SI units-force and length, intended for transferring a unit of magnitude of mechanical stresses to measuring instruments that implement a temporary method of acoustic type of nondestructive check based on the phenomenon of acoustoelasticity. The article discusses the key stages of the development of reference materials: selection of the source material for reference materials; study of the homogeneity of the source material; carrying out experimental studies with the use of reference device (the state standard unit of strength of the 1st category) and establishing the metrological characteristics. As a result of type approval tests CRM was registered in the State Register of CRM’s as GSO 11544-2020/11545-2020. The certified characteristics of the CRM are proportional limit mechanical stress σpl; proof strength σ02 (plastic extension 0,2 %); tensile strength σв; modulus of elasticity E. Limits of the relative error of the certified values at a confidence level of 0,95 do not exceed 12 %. The authors believe that the CRM of the mechanical properties of steels GSO 11544-2020/11545-2020 will provide metrological traceability of the results of measurements of mechanical stresses by measuring instruments that implement the by acoustic type of nondestructive check, when using the GSO as a basis for comparison in the verification scheme.