SINTEF (a Norwegian research Co.) made studies of the sensitivity to hydrogen embrittlement (HE) of super 13Cr martensitic stainless steels. These tests are summarised in this paper. Both slow strain rate (SSR), 4-point-bend and fracture mechanics testing have been conducted. The effect of temperature, cathodic protection (CP), applied potential, strain rate and H2S were investigated.
Laboratory testing to qualify several materials for high strength fastener applications for two projects has shown that, in the presence of cathodic protection, nickel alloys 718 and 725 offer the best resistance to hydrogen embrittlement and are available in the strength/size required for high pressure and moderate temperature applications for sub-sea applications.
In seawater, higher strength nickel-copper alloys are used as alternatives to copper alloys. These can be susceptible to chloride stress corrosion cracking and hydrogen embrittlement in conditions where cathodic protection is utilized. Copper-Nickel-Tin alloys (CuNiSn) show low corrosion rates in the free and coupled conditions. Resistance to hydrogen embrittlement is demonstrated.
The alloys (used in chem/process industries) are usually in the solution annealed condition & must be fast cooled from the annealing temperature to prevent the precipitation of third phases such as sigma chi nitrides & alpha prime. This paper describes a reactivation test to detect alpha prime - used with 22%Cr and 25% Cr alloys. Case studies.