Hydrogen-induced cracking prevention

Figure 19. Dramatic prevention effect introduced by REM additions against disintegration of line pipe steel by hydrogen-induced cracking (HIC)...

W. Bruckhoff, O. Geier, K. Hofbauer, G. Schmitt, D. Steinmetz. Rupture of a Sour Gas Line Due to Stress Oriented Hydrogen Induced Cracking - Failure Analyses, Experimental Results and Corrosion Prevention. NACE Corrosion/85, Paper 389, Boston, USA, 1985-03-25/29. 

Several researchers have revealed a marked effect of rare earths on improving the thicknesswise ductility of steels resistant to lamellar tear, reducing the anisotropy of steels, and preventing hydrogen-induced cracking, etc. Basically, all these seem to be attributable to the following four principal functions achieved by rare earths and Ca addition to the molten steels ... 

The higher-strength martensitic steels are at risk for stress corrosion cracking in seawater. The stress corrosion cracking can be prevented by means of cathodic corrosion protection, but the protective potential must be limited to about Uh = -0.5 V, since otherwise hydrogen-induced stress corrosion cracking may occur. 

It has been reported that hydrogen embrittlement is a form of stress corrosion cracking (SCC). Three basic elements are needed to induce SCC the first element is a susceptible material, the second element is environment, and the third element is stress (applied or residual). For hydrogen embrittlement to occur, the susceptible material is normally higher strength carbon or low-alloy steels, the environment must contain atomic hydrogen, and the stress can be either service stress and/or residual stress from fabrication. If any of the three elements are eliminated, HE cracking is prevented. 

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