Strength of Initially Virgin Martensites at -196 C After Aging and Tempering.
Abstract
The compressive strength at -196 C of martensites in Fe-O.26%C-24%Ni, Fe-O.4%C-21%Ni, and Fe-O.4%C-18%Ni-3%Mo alloys, all with sub-zero M(s) temperatures, has been determined in the virgin condition and after one hour at temperatures from -80 to +400 C. The effects of ausforming (20% reduction in area of the austenite by swaging at room temperature prior to the martensitic transformation) were also investigated. For the unausformed martensites, aging at temperatures up to 0 C results in relatively small increases in strength. Above 0 C, the age hardening increment increases rapidly, reaching a maximum at 100 C during the carbon clustering stage and prior to the precipitation of carbides. Above C, the strength decreases continuously with increasing tempering temperature except for the molybdeum-containing alloy, which exhibits secondary hardening on tempering at 400 C. For the measurement martensites, the response to aging at sub-zero temperatures is greater than for unausformed material. Strength again passes through a maximum on aging at 100 C. However, on tempering just above 100 C, the ausformed materials show a slower rate of softening than the unausformed martensites. The strengthening produced by the ausforming treatment is largest for the Fe-0.4%C-18%Ni-Mo alloy, but there is no evidence of carbide precipitation in the deformed austenite to account for this effect of molybdenum. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 31, 1981
- Accession Number
- ADA110656
Entities
People
- George T. Eldis
- Morris B Cohen
Organizations
- Massachusetts Institute of Technology