The purpose of diploma thesis was to study, how the stress rate and the shape of specimen influence the results of tensile test. Namely, the DIN EN ISO 6892-1:2016 standard for metallic material tensile testing permit execution of a test at various stress rates, and various specimen shapes.
Various standardized forms of specimens were manufactured from the hot rolled rods of the VCNMO200 and PK323MO steels. All specimens were cut transversely to the direction of rolling and at the same positions. Measurements were carried out in two independent laboratories. Results are compared and represented according to various tensile testing machines, operators, stress rates and specimens shapes. In order to determine the influence of the stress rate on the results of the tensile test, the specimens were tested at three different stress rates in the range from 6 MPa s-1 to 60 MPa s-1. In order to determine the influence of the specimen's shape on the results of the tensile test, different shapes of specimens were tensed at the same stress rate of 30 MPa s-1.
We established that the stress rate and specimen shape affect the tensile test results, but the influence is minimal. Furthermore, difference between the results obtained with various tensile test machines was minimal, but only when tensile test machines with controlled parameters of tensile testing were used.