Transgranular stress-corrosion cracking (TGSCC) is now widely believed to be an essentially brittle process. The debate has shifted from the reality of the stepwise brittle fracture to the role of the environment in nucleating it. However, published correlations of 'bare surface' electro-chemical kinetics with the rate of TGSCC continue to be successful, notably for alpha brass in sodium nitrate solution. By comparing the results of two techniques (scratching and rapid straining) it is shown that the published bare surface anodic current densities in this system are at least one order of magnitude too high. The revised values fit neatly into the 'film-induced cleavage' picture of TGSCC. In another system (alpha brass in cuprous ammonia solution) the anodic process is dezincification to a depth of 20-40 nm, followed by cleavage on the order of 1 mu m; here the inadequacy of the anodic process to account for the cracking is more obvious. Some suggestions are made as to how one can incorporate cleavage into a kinetic model of SCC, with the objective of harmonizing film-induced cleavage with earlier electrochemical models.
|Original language||English (US)|
|Title of host publication||Unknown Host Publication Title|
|Publisher||Metallurgical Soc of AIME|
|Number of pages||10|
|State||Published - Dec 1 1986|
ASJC Scopus subject areas