Development of reproducible and increased strength properties in thick extrusions of low-alloy Al-Zn-Mg-Cu based AA 7075
- Defence Metallurgical Research Lab., Hyderabad (India)
The present article deals with the studies undertaken to resolve an industrial problem, where the desired minimum tensile properties in the T651 temper, i.e., 0.2 pct PS = 530 MPa, UTS = 580 MPa, and elongation (in 50-mm gage length) = 7 pct, were difficult to obtain in a reproducible manner in low-alloy (i.e., alloy containing major alloying elements in amounts not greater than those specified by the nominal compositions in the specification) AA 7075 round bar extrusions having 80-mm diameter. The present results that the use of the two-step artificial aging treatment enables higher strength properties to be achieved in the alloy with reduced Zn and Mg contents has an additional advantage in that the susceptibility to SCC is known to reduce with decreasing Zn + Mg contents in this alloy series. This, together with the previously documented results that the strength properties of these materials subjected to the two-step artificial aging treatments (employed for increasing the SCC resistance) are not affected by the time delay between quenching and aging, should make the use of the two-step artificial aging treatment commercially more attractive compared to the single-step artificial aging treatment used for the T6/T651 temper.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 556489
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 28, Issue 11; Other Information: PBD: Nov 1997
- Country of Publication:
- United States
- Language:
- English
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