The methodical peculiarities of the investigation of portal crane rolled steels degradation

Abstract

Rolled structural steels of port structures, operating under intensive cyclic loading, are particularly susceptible to the degradation of their mechanical properties. Advantages of the investigation of operational degradation of steels based not on fatigue strength characteristics, but on characteristics of resistance to brittle fracture using the example of determining the impact strength of longitudinal and transverse Charpy samples in relation to the rolling direction of sheet metal for 10 local areas at different structural nodes of portal crane are analyzed. This is caused to a great extend by micro-layering along the stretched fibers in the rolling direction of the rolled product. Accordingly, the mechanical properties of the metal become particularly sensitive to the direction of samples cutting in relation to the direction of rolling. Therefore, in order to evaluate the steel operational degradation it is recommended to use transverse samples in which the direction of micro-laayering coincides with the direction of rolling. Possible role of the marine environment in enhancing the degradation of steel due to its flooding properties is also considered in this paper.