Abstract
Cathodic charging of notched 304 austenitic stainless steel specimens was carried out in an aqueous solution of 1N H₂SO₄ containing 250 mg/l NaAsO₂ at room temperature and 70±2°C while undergoing tensile strain over a wide range of crosshead speeds of 833 µm/s, 83 µm/s, 8.3 µm/s, 833 nm/s, 83 nm/s, and 9.8 nm/s.
Tests at room temperature (22±2°C) resulted in a marked reduction in the elongation to fracture ratio (ε_sol/ε_air) with the reduction of the crosshead speed. However, little reduction was observed for the stress to fracture ratio (σ_sol/σ_air). Cleavage and intergranular fractures were the predominant fracture modes when tests were carried out at a low crosshead speed. The extent of these modes of fracture was observed to increase with reducing crosshead speed.
Cathodic charging of 304 austenitic stainless steel at 70±2°C caused less reduction in the elongation to fracture ratio compared to the tests carried out at room temperature. Consistent with the room temperature test results, the reduction in the elongation to fracture ratio was found to increase with the reduction of the crosshead speed. However, restoration in the elongation to fracture ratio was exhibited by 304 austenitic stainless steel specimens tested at the lowest crosshead speed of 9.8 nm/s. These results are in good agreement with the observed fracture modes.
agreement with the finding that the hydrogen embrittlement is temperature and strain dependent. Cleavage fracture associated with the plastic deformation was the predominant fracture mode exhibited by 304 austenitic stainless steel specimens tested at 70±2°C over low crosshead speed.