Hydrogen Embrittlement of Steels under Constant Load Rupture Test (Part 5)

Effects of microstructure on the hydrogen embrittlement of steels

Abstract

The sensitivity to hydrogen embrittlement of every kind of microstructure was examined by means of Constant Load Rupture Test. Hydrogen was charged into a specimen with each structure cathodically under given constant load.
In this report, the microstructures examined were ferrite+pearlite, sorbite, troostite, bainite+martensite and martensite.
The martensite was the most embrittled by hydrogen. This depended upon the presence of carbon in the crystal lattice (in the presence of relatively high carbon the martensite was composed of twinned martensite in the microstructure.).
Ferrite+pearlite structure appeared to be more insensitive to hydrogen embrittlement than other microstructures and it would be considered that this depended upon the carbide (cementite).
The relationship between the sensitivity to hydrogen embrittlement and the hardness (Hv) corresponding to each structure was linear. Therefore the sensitivity to hydrogen of any materials could be roughly estimated by their hardness.