Metal treatment – Compositions – Heat treating
Patent
1988-03-22
1989-05-16
Stallard, Wayland
Metal treatment
Compositions
Heat treating
148 12R, 72200, 72201, C21D 700, C21D 702, C21D 713
Patent
active
048306835
ABSTRACT:
The invention relates to apparatus and accompanying methods for use therein for forming a material (504), which has high strength and good workability, by rapidly deforming a suitable base metal (501) having a banded structure, such as illustratively a previously cold worked plain low carbon steel alloy, in order to generate a high rate of change in its internal energy which depresses the transformation temperatures of the base metal and thereby induces an allotropic phase transformation to occur therein. This rapid deformation can be produced through rolling, extrusion or forging and causes an extremely high heating rate to occur at each surface of the base metal. Prior to being deformed, the base metal is maintained at a fairly low temperature, e.g. at or near room temperature. The tooling, preferably rolls, that is used to provide the deformation is maintained at a modestly elevated temperature. Subsequent rapid deformation of the base metal causes an extremely high heating rate to occur at each surface thereof which, in turn, depresses the upper and lower on heating transformation temperatures at surface regions of the base metal and thereby causes the banded structure of the metal situated in these surface regions to transform into equiaxed grains. If the heating rate is insufficient to raise the temperature of the core of the base metal, which contains banded grains, to a level that causes metal in the core to transform, then the core will retain its banded cold worked structure. Consequently, the transformed surface regions (510, 510') will possess an equiaxed grain structure which provides increased ductility; while the core (511) of the material retains its banded (deformed) grain structure which provides high strength. Hence, the surfaces (512, 512') of the material become soft and ductile while the core possesses considerably higher amounts of hardness, yield and tensile strength than either surface. This material advantageously exhibits both good workability and relatively high strength. Alternatively, if the deformation rate is increased, such as by using small diameter rolls, in order to increase the bulk heating rate of the base metal and the appropriate thickness of the base metal has been chosen, then the entire base metal transforms into equiaxed grains. In this case, the resulting material (404) possesses a ductility and hence workability similar to that of a fully annealed structure.
REFERENCES:
patent: 2393363 (1946-01-01), Gold et al.
patent: 2814578 (1957-11-01), White
patent: 3323953 (1967-06-01), Lesney
patent: 3855013 (1974-12-01), Prohaszka et al.
patent: 3877281 (1975-04-01), Shimizu et al.
patent: 3929517 (1975-12-01), Nakamura et al.
patent: 4046598 (1977-09-01), Janzon
patent: 4060428 (1977-11-01), Wilson et al.
patent: 4086105 (1978-04-01), Mayrhofer et al.
patent: 4108695 (1978-08-01), Paulitsch et al.
patent: 4146411 (1979-03-01), Dewsnap et al.
patent: 4204884 (1980-05-01), Berg et al.
patent: 4375375 (1983-03-01), Giamei et al.
patent: 4395296 (1983-07-01), Abrams
patent: 4410372 (1983-10-01), Takahashi et al.
patent: 4426235 (1984-01-01), Sudo et al.
patent: 4466842 (1984-08-01), Yada et al.
Y. Lakhtin, Engineering Physical Metallurgy (.COPYRGT. 1965: Gordon and Breach; New York), p. 161.
E. J. Teichert, Metallography and Heat-Treatment of Steel (Ferrous Metallurgy--vol. III), .COPYRGT. 1944, McGraw-Hill Book Company, Inc., New York, p. 137.
The desk edition of The Metals Handbook (.COPYRGT. 1985, American Society of Metals; Metals Park, Ohio), p. 28.2.
C. Keyser, Basic Engineering Metallurgy--Theories, Principles and Applications (.COPYRGT. 1959: Prentice-Hall, Inc.; Englewood, New Jersey, p. 189.
L. Guillet et al., An Introduction to the Study of Metallography and Macrography (.COPYRGT. 1922: McGraw-Hill Book Company, Inc.; New York) pp. 80-81.
H. J. McQueen, "The Experimental Roots of Thermomechanical Treatments for Aluminum Alloys", Journal of Metals, vol. 32, No. 2, Feb. 1980, pp. 17-25.
R. S. Cremisio, "The New Technology of Rapid Heating and Strain Rate Studies", 1965 Transactions of the Vacuum Metallurgy Conference.
J. Dominik, "The Peculiarities of Phase Transformations in Bearing Steels at High Heating Rates", Kovove Mater., vol. 22, No. 2, 1984, pp. 155-163.
W. Reinhard, "The .alpha.-.gamma. Phase Conversion of Iron at High Heating Rates", Freib. Forschungsch. B. Metall. Werkstofftech., (B244), 1985, pp. 60-74.
Michaelson Peter L.
MRE Corporation
Stallard Wayland
LandOfFree
Apparatus for forming variable strength materials through rapid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for forming variable strength materials through rapid , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for forming variable strength materials through rapid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2319937