Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1993-03-08
1995-05-09
Kastler, Scott
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
72352, 72710, 148695, 148697, 148701, 148437, 148439, C22F 104
Patent
active
054136504
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a method of producing components of aluminium or alloys thereof having enhanced mechanical properties, particularly toughness and ductility in a transverse direction. The present invention also concerns a final thermomechanical treatment which further enhances mechanical properties.
The development of ultra high strength aluminium alloys, such as the 7000 series alloys (Registration Record of the Aluminium Association Inc.), has received much attention over the past 30 years or so. A particular problem with these materials is a reduction in overall ductility and, especially in the transverse directions and particularly the short transverse direction, mechanical properties such as ductility and fracture toughness. Attempts to improve transverse properties have largely employed the use of super pure base materials and/or a process of intermediate thermomechanical treatment (ITMT) seeAlluminio April 1975, pp 193-213, to produce a fine recrystallised grain structure.
It is known that the mechanical properties of precipitation hardened alloys can be markedly improved by the correct application of final thermomechanical processing techniques (FTMT). The attainment of ultra high strength in alloys such as those of the 7000 series has required that enriched compositions, particularly with regard to Zn, Mg and Cu be developed These rich alloys however present serious casting difficulties where large commercial size ingots are needed and work has therefore been done on small scale laboratory cast ingots or from alloys produced by powder routes.
It has been possible to obtain high values for longitudinal tensile properties but at the cost of a low ductility.
For example Roberts, Powder Metallurgy, AIME Interscience Publishers, New York 1961, obtained longitudinal tensile properties of 816 MPa with a 4% elongation with extruded powder compacts. Moreover Haar, Reports to Frankford Arsenal for period 1961-65 Alcoa Research Laboratories, obtained a value as high as 861 MPa but with low ductility using a powder route. In a separate study by Di-Russo, Alluminio Nuova Met., 1967, Vol. 36, pp 9-15, using small diameter direct chill ingots he obtained a strength level of 772 MPa with an elongation of 3%. Flemings and co-workers, Met. Trans. Vol. 1, January 1970, pp 191-197, obtained similar results using alloys rapidly solidified in 1/8" thick moulds and splat cooled samples. Values as high as 796 MPa tensile strength were obtained but with an elongation of only 1.8% after essentially cold working solution treated and aged materials. Mercier and Chevingny, Memoirs Scientifiques Rev. Metallurgy LX No. 1 1963, using a process of plastic deformation after complete T6 heat treatment recorded values as high as 740 MPa with an elongation of 3.5% for a 7000 series alloy A-Z8GU.
With regard to enriched compositions, U.S. Pat. No. 3,198,676 by Sprowls describes the application of thermal treatments for improved stress corrosion and fracture resistance.
Many thermomechanical studies involving the interaction of aging and plastic deformation have also been carried out on material produced from conventional D.C. cast ingots, with consequently lower strength, although improved fatigue performance, stress corrosion resistance, and fracture toughness have been reported. The lack of commercial use of final thermomechanical treatments in high strength 7000 series extrusions is a result of the poor transverse properties of these extrusions.
The use of vibrations induced in a component has been known for stress relief, particuarly in steel components but also for aluminium. The technique of Vibrational Stress Relieving (VSR) has been described in an article by R. A. Cloxton in The Journal of the Bureau of Engineer Surveyors, Volume 10, Nos. 1 and 3, 1983. Its use is as an alternative or in addition to thermal stress relief.
In the VSR technique, as typically applied for stress relief, a vibrator is engergised and scanned slowly up to its maximum frequency e.g. 0-200 Hz in about 10 minutes. The response of the comp
REFERENCES:
patent: 3622404 (1971-11-01), Thompson
patent: 4001053 (1977-01-01), Igisu
patent: 4462238 (1984-07-01), Goodfellow
patent: 4797165 (1989-01-01), Bretz et al.
patent: 4861391 (1989-08-01), Rioja et al.
K. R. Van Horn "Aluminium" vol.3: Fabrication and Technology, Dec. 1967, American Society for Metals, Ohio; C. R. Anderson et al Extrusion.
Metals Abstract vol. 14, No.1, p. 49, Materials Information, London GB Dec. 1981 Abstract No. 22-0054 R. A. Claxton, "Vibratory Stress Relieving-Practice and Theory".
Materials Science And Engineering: vol. 61, No. 1, Dec. 1983, Amsterdam, NL, pp. 67-77; M. M. Shea et al: "Enhanced Age Hardening of 7075 Aluminium Alloy After Ultrasonic Vibration".
Dixon William
Jarrett Martin R.
Alcan International Limited
Kastler Scott
Koehler Robert R.
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