Establishing Equations for Calculating the Change of Lower Yield Point Depending on the Time of Corrosion Effect

In this paper, equations are established to predict how the values of the lower yield point in the stress-strain curve depending on a time of corrosion influence will change. Although this point is of theoretical importance in the theory of strength of materials, its change in corroded steel is of practical importance, since this point determines according to the theory which minimum load or stress is required to maintain the plastic behavior of material. A well-founded mathematical principle was used to process experimentally obtained data in two main directions - the stochastic method and the average method. Diagrams of the variation of values in corroded steel were drawn up and equations of the 9th degree were established using polynomial approximation.