Tensile properties of precracked tempered martensitic steel specimens tested at ultralow strain rates in high-pressure hydrogen atmosphere

• Published in: Philosophical magazine letters Vol. 95; no. 5; pp. 260 - 268
• Main Authors: Sasaki, Daisuke, Koyama, Motomichi, Hamada, Shigeru, Noguchi, Hiroshi
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 04.05.2015; Taylor & Francis Ltd
• Subjects: Atmosphere; Atmospheres; Chromium; Helium; Hydrogen; hydrogen in metal; hydrogen-enhanced decohesion; hydrogen-enhanced localized plasticity; low strain rate; Martensitic stainless steel; Martensitic stainless steels; Nickel; precracked specimen; Pressure; Steels; Strain rate; Tensile strength
• ISSN: 0950-0839; 1362-3036
• DOI: 10.1080/09500839.2015.1049574

Tensile tests were performed on precracked Cr-Mo martensitic steel (C: 0.38, Si: 0.22, Mn: 0.84, P: 0.024, S: 0.021, Ni: 0.08, Cr: 1.11, Mo: 0.15, Cu: 0.12, Fe: bal. (wt%)) specimens at various strain rates (ranging from 6.5 × 10 −8 s −1 to 1.0 × 10 −4 s −1 ) in high-pressure (95 MPa) hydrogen and helium atmospheres. Irrespective of the strain rate, the tensile strength in the helium atmosphere was 1400 MPa. In the hydrogen atmosphere, the tensile strength decreased to less than 600 MPa at a strain rate of 2.0 × 10 −5 s −1 . However, the tensile strength increased to 900 MPa when the strain rate was decreased to 6.5 × 10 −8 s −1 . This recovery of the tensile strength was because of the decrease in the local stress in the vicinity of the precrack because of hydrogen.