CRACKING RATES DETERMINATION DURING SCC WITH A SLOW STRAIN-RATE - APPLICATION TO INHIBITION

On a carbon steel in carbonated medium with pH 9 and after breakage ob tained by slow traction, lengths of non crossing cracks were measured micrographically. An experimental cracking speed could thus be deduced . Calculation modes for cracking speeds previously proposed by other a uthors do not make it possible, by excess as well as by lack, to take into account the results observed. New calculation methods were then p roposed. This approach was then applied to corrosion inhibition under stress for the same system. The evolution of equilibrium conditions ma de it possible to choose the most efficient one. The results show that cracking could be stopped. This results either in a competitive adsor ption between aggressive and passivating species on surfaces freshly c reated during plastic deformation, or a modification of the protective film improving its plastification. In addition, the method used makes it possible, to test inhibitors and to deduce the criteria of choice.