摘要
Five Femnal alloys with various ferrite/ austenite were prepared by mainly adjusting the carbon content. Hydrogen compatibility of these alloys was investigated. A slow extension rate tensile test in one atmosphere of hydrogen gas showed that hydrogen embrittlement (HE) increased with the content of ferrite in the alloys. The alloy with a full austenite phase was strong, ductile, and essentially immune to HE, whereas the one with full ferrite was weaker, very brittle, and suffered serious damage in hydrogen. A sustained load test was further conducted in hydrogen gas at 25°C to 75 °C for the alloys with 10, 35, and 65 pct ferrite. No subcritical crack growth occurred in the alloy with 10% ferrite. Typical three-stage environment-assisted crack growth was observed for the alloys with 35 and 65 pct ferrite. A kinetics study of the subcritical crack growth indicated that the cracking rate was basically controlled by hydrogen transport through the ferrite grains. Austenite phase could be embrittled provided sufficient hydrogen was dissolved. To reduce HE in Femnal alloys, the content of ferrite should be reduced; this can be achieved mainly by controlling the carbon content in the alloys. © 1975, American Society for Metals, The Melallurgical Society of AIME. All rights reserved.