A Stress Corrosion Cracking Model.
Abstract
The characteristic susceptibility to stress-corrosion cracking exhibited by certain titanium and many aluminum alloys was studied. Mechanisms germane to establishing the conditions for stress-corrosion cracking in heat-treatable alloys during precipitation hardening are covered. A 7075 A1 alloy and an A1-Zn-Mg ternary alloy were used in construction of a stress-corrosion model. The model showed that the stress corrosion cracking susceptibility of A1 alloys becomes reduced if one or more of the following can be realized: (1) elimination of the precipitation-free zone, PFZ, through proper heat treatment; (2) inducement of the formation of primary precipitates in the PFZ to enhance hardening; (3) inducement of the segregation of solute atoms to produce sufficient grain boundary hardening into the PFZ; (4) reduction of the PFZ width to a practical minimum; and (5) addition of an additive such as Cd, Sn and In to initiate precipitation of CuAl2 in the PFZ during initial aging. The resistance to stress-corrosion cracking will be increased because of: (1) the virtual elimination of the difference in mechanical properties between the PFZ and the train interior due to differences in thermal history, and (2) due to the presence of Cd, the reduction of the anodic effect at the grain boundaries. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1971
- Accession Number
- AD0726713
Entities
People
- Richard C. Fabiniak
- Thaddeus J. Fabiniak
Organizations
- Calspan