On the elastic interaction of hydrogen with precipitates in lath martensite

The interaction of hydrogen with dislocations is well established, but its interaction with other structural features in a material has not been investigated or discussed to any appreciable degree. It is the intent of this discussion to examine the preference of precipitates for hydrogen atoms in a plain carbon steel, which is quenched to a martensitic structure and tempered. This structure represents one of the most susceptible to hydrogen embrittlement in the as-quenched condition and the most resistant in the highly tempered condition. One of the prominent features of this microstructure is the carbide precipitate and its transformational and morphological changes that result on tempering. The ability for trapping hydrogen, from an elastic energy standpoint, is seen to decrease with increasing loss in coherency of the precipitate. An energy for interaction between coherent precipitates and hydrogen atoms is calculated.