Relationships Between Size Proportions, Distances Between the Large Impurities, Hardness and Strength Parameters of High-Quality Steel

Abstract. High purity steels are used for responsible structural elements operating under cyclic loads. An important issue is the appropriate selection of steel to ensure the expected durability of the construction material. Ensuring durability requires testing. One of the methods to find out the durability of a material is indirect testing. With their help, it is possible to draw conclusions about the fatigue life of the material based on simple tests, including hardness tests, which require the estimation of the proportionality coefficient allowing comparison of durability with hardness. To correctly estimate durability based on hardness, it is necessary to know the impact of real conditions on the microstructure and properties of steel. This necessitates the determination of equations enabling the connection of the actual microstructure of the steel (main phase, morphology of impurities) with the parameters characterizing the fatigue strength. High reliability of the obtained results requires tests to be carried out in natural conditions, which cannot be ensured by laboratory conditions. The objectives set out above were achieved in the research planned and presented in this manuscript.