Relationship between microstructure and hydrogen absorption behavior in a V-bearing tempered martensitic steel

TEM observations and hydrogen thermal desorption analysis were performed to understand the relationship between microstructure and hydrogen absorption behavior in a V-bearing steel. The hydrogen absorption property was changed by controlling VC precipitation with changing tempering temperature from 573K to 973K. Hydrogen was absorbed into the specimen by cathode charging at a constant condition, and its content was examined by thermal desorption analysis. Energy-filtering and high-resolution TEM methods were employed to observe the size and distribution of VC precipitates. When the specimen was tempered at around 873K, the hydrogen absorption content was markedly increased; 4 times higher than that of the as-quenched specimen. TEM observations showed that this significant hydrogen absorption is attributed to nano-scale VC precipitates.