Metallurgical effects of strontium on wrought 6061 alloys
- McGill Univ., Montreal, Quebec (Canada)
- Timminco Metals, Haley, Ontario (Canada). Research and Development Center
Aluminum extrusion alloys contain a variety of intermetallics that form during ingot solidification. In the 6061 series of alloys, iron combines with aluminum and silicon to form two types of intermetallics, {beta}-AlFeSi and {alpha}-AlFeSi. The type of the intermetallic that is present in these alloys will have an important bearing on the homogenization time, workability and quality of the surface finish of the parts produced form these alloys. Solidification of 6061 alloy normally results in the formation of the acicular {beta} phase which detrimentally affects alloy ductility. However, it has been demonstrated that the addition of about 150--300 ppm of strontium to 6061 alloy will make the preferred {alpha} the dominant intermetallic phase which forms during billet solidification. This enables the T4 billet homogenization time to be significantly shortened by eliminating the lengthy time, in excess of 6 hours, needed to transform the normal as-cast {beta} phase to the more desirable {alpha} form. It has also been demonstrated that 6061 extrusions produced from strontium-free billets require approximately 6 hours of T4 billet homogenization at 575 C to achieve the same surface finish obtained in strontium containing extrusions with billet T4 times of less than 2 hours.
- OSTI ID:
- 372024
- Report Number(s):
- CONF-960202--; ISBN 0-87339-312-0
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM BASE ALLOYS
CASTING
CHEMICAL COMPOSITION
COPPER ADDITIONS
HEAT TREATMENTS
INTERMETALLIC COMPOUNDS
IRON ADDITIONS
MAGNESIUM ADDITIONS
MECHANICAL PROPERTIES
METALLOGRAPHY
METALLURGICAL EFFECTS
MICROHARDNESS
MICROSTRUCTURE
OPTICAL MICROSCOPY
ROUGHNESS
SCANNING ELECTRON MICROSCOPY
SILICON ADDITIONS
STRONTIUM
TENSILE PROPERTIES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY SPECTROSCOPY