Characterization of superplastic deformation behavior of a fine grain 5083 Al alloy sheet

Journal Article · Mon Jul 01 00:00:00 EDT 1996 · Metallurgical Transactions, A

DOI:https://doi.org/10.1007/BF02651938· OSTI ID:282238

Verma, R; Friedman, P A; Ghosh, A K ^[1]; Kim, S; Kim, C ^[2]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
2. GM Research and Development Center, Warren, MI (United States)

Superplastic deformation behavior of a fine grain 5083 Al sheet (Al-4.2 pct Mg-0.7 pct Mn, trade name FORMALL 545) has been investigated under uniaxial tension over the temperature range of 500 C to 565 C. Strain rate sensitivity values >0.3 were observed over a strain rate range of 3 {times} 10{sup {minus}5} s{sup {minus}1} to 1 {times} 10{sup {minus}2} s{sup {minus}1}, with a maximum value of 0.65 at 5 {times} 10{sup {minus}4} s{sup {minus}1} and 565 C. Tensile elongations at constant strain rate exceeded 400 pct; elongations in the range of 500 to 600 pct were obtained under constant crosshead speed and variable strain rates. A short but rapid prestraining step, prior to a slower superplastic strain rate, provided enhanced tensile elongation at all temperatures. Under the two-step schedule, a maximum tensile elongation of 600 pct was obtained at 550 C, which was regarded as the optimum superplastic temperature under this condition. Dynamic and static grain growth rate was appreciably higher than the static growth rate and that the dynamic growth rate based on time was more rapid at the higher strain rate. Cavitation occurred during superplastic flow in this alloy and was a strong function of strain rate and temperature. The degree of cavitation was minimized by superimposition of a 5.5 MPa hydrostatic pressure during deformation, which produced a tensile elongation of 671 pct at 525 C.

• Sponsoring Organization: USDOE
• OSTI ID: 282238
• Journal Information: Metallurgical Transactions, A, Vol. 27, Issue 7; Other Information: PBD: Jul 1996
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
33 ADVANCED PROPULSION SYSTEMS
ALUMINIUM BASE ALLOYS
TENSILE PROPERTIES
GRAIN GROWTH
MAGNESIUM ALLOYS
AUTOMOBILES
MATERIALS
MANGANESE ADDITIONS
CHROMIUM ADDITIONS
IRON ADDITIONS
CHEMICAL COMPOSITION
TEMPERATURE DEPENDENCE
STRAIN RATE
ELONGATION
CAVITATION
GRAIN BOUNDARIES
PRECIPITATION