Chapter 4 Stress Corrosion Cracking O. F. Aly and M. Mattar Neto Additional information is available at the end of the chapter http://dx.doi.org/10.5772/57349 1. Introduction Stress Corrosion Cracking (SCC) is a sudden and difficult-to-predict severe degradation mode of failure of nuclear, petrochemical, and other industries. This chapter aims to give a general view for SCC based in the authors experience on more than ten years working with this kind of failure (mainly in PWR Nuclear Plant) in the Brazilian Energy and Nuclear Research Institute. SCC is a cause of several serious accidents due to sudden failures difficult to predict, in equipments related to industrial plants, pressure vessels, high pressure piping, ducts, and structures. One gives three following examples: a) Silver Bridge colapse in 1967, over Ohio River at Point Pleasant, West Virginia, USA with 46-killed people [1]; b) Catastrophic disk rupture of a steam turbine from nuclear power plant Hinkley Point Power Station, England in 1969 with enormous material losses, machine destruction, and financial losses due to the long period of operation impeachment [2]; c) Flixborough accident, England in 1974, due to a reactor failure, has caused 28 killed people, several injured people, and big material losses [3]. SCC may be classified as an Environmental Assisted Cracking (EAC), besides Corrosion Fatigue (CF) and Hydrogen Induced Cracking (HIC). The relationship between these three types of failures can be showed in Figure 1 where the EAC domain is the union of the three circles, each one representing the three failure modes. The SCC is caused by three main factors: a) Material susceptibility; b) Environmental condition; c) Tensile stresses (applied and residual). Sometimes CF is considered a particular case of SCC where the load is cyclical, and HIC should be considered as a mechanism of SCC [4]. The EAC scientific interest began in the late 19th century due to apparently spontaneous cracks which occurred in brass cartridges cases belonging to the British Army in India during the monsoon seasons: so they were appealed “season cracks”, before when this kind of crack was just understood, and after appealed “stress corrosion crack” [5] – the reference [5] is a com‐ prehensive article which should be read by all that want more information about the historical research of EAC. © 2014 Aly and Neto; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.