This paper describes the environmentally induced ductility change in the heat-affected-zone (HAZ) of high strength low alloy steel. Tensile tests were carried out on the samples with or without hydrogen absorption at elevated temperature.
Even for QT-type steel there was a possibility of ductility loss due to dynamic strain aging in the HAZ. Under the temperature conditions which promoted dynamic strain aging, the ductility decreased at the temperature range between room temperature and 250°C. This was due to an increase in free nitrogen and the coarsening of pre-austenite grain size. The ductility loss was significant at the HAZ with coarse pre-austenite grain size or high free nitrogen content.
When the materials susceptible to hydrogen embrittlement were used in the environments which promote dynamic strain aging, the ductility decreased remarkably at elevated temperature by the independent but simultaneous effects of dynamic strain aging and hydrogen embrittlement.
