Electrode Potential and its Effect on Crack Growth

A differential aeration galvanic cell consists of differences in oxygen concentration, leading to pitting and cracking in distilled water (96). 

2 Alloy/Liquid Interface The following table 1.2 lists some alloy-environment combinations that result in SCC. This table serves as a general guide (9). 

SCC is often encountered in hot gaseous atmospheres on materials under creep or fatigue conditions. SCC susceptibility of titanium alloys in moist chlorine, dry HCl, and dry hydrogen has been observed. The titanium alloy (Ti-8Al-lMo-l V) exhibits cracking in moist chlorine gas at 288 C. Binary titanium alloys also exhibit cracking in moist chlorine at 427 °C (96). 

Hot salt SCC and hot gaseous SCC of titanium alloys have been reported to occur. Irradiation-assisted SCC has been reported to occur in nuclear reactors (96). 

HE is the loss of ductility of materials containing hydrogen, which occurs in high-strength steels, primarily quenched and tempered and precipitation-hardened steels, with tensile strengths greater than about 1034 MPa. There are two types of HE (9, 91). 

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