The mathematical model offered below for description of subcritical crack growth due to local hydrogen embrittlement is based on the assumptions: (1) the crack tip is a source of protons in metal, (2) the rate of the source is directly proportional to the crack opening displacement, the proportionality coefficient being determined by a certain electrochemical reaction, and (3) the effect of protons on a metal is fully described by the magnitude of their local concentration. The combined analysis of two different processes is advanced. The first is the local diffusion of protons near a crack tip, the other is the elastic-plastic deformation of fine and superfine structure of the crack tip. In result, the theoretical dependence of crack growth velocity on stress intensity factor is obtained. It is well approximated by the linear diagram in the range of practical interest. The analysis of some test data of Carter, Johnson, Ryder and others is also given.

Subject
Hydrogen induced cracking, Hydrogen embrittlement, Crack growth, Water, Materials, Stress intensity, Sodium chloride, Stress cracking, Constants, Sodium chloride solution, Silicon, Metals, Steel
© 1973 National Association of Corrosion Engineers
1973
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