A model for calculating solubility of hydrogen in steel

Abstract

A model has been developed for calculating the hydrogen solubility in steel on the basis of composition (S, Ti, B) and grain size, with the objective of improving the control of hydrogen content in steel products. The effects of sulphur are in agreement with previous experience, but complex effects have been observed with variations in titanium and boron contents. The model defines trap sites in crystallographic terms for the various phases and features of interest. Segregation effects have been studied using laboratory casts and with composites using continuously cast slab from which the natural segregation has been removed. Segregated regions absorb large amounts of hydrogen, but the crack threshold is reduced such that the composites have much lower safe hydrogen levels than unsegregated material. The effects of assumptions in the model on number of traps and binding energies are considered.