Title: Variable strength materials formed through rapid deformation
Application Number: 88102197 Application Date: 1988.03.26
Publication Number: 1021712 Publication Date: 1988.10.26
Approval Pub. Date: 1993.05.26 Granted Pub. Date: 1993.05.26
International Classifi-cation: C21D8/00;C22F1/00
Applicant(s) Name: MRE Corp. Address:
Inventor(s) Name: Hugo Stanley Ferguson
Attorney & Agent: YANG LIQIN
Abstract:
    The invention relates to a material, having adjacent regions of differing strength and ductility, that has been formed by rapidly deforming a suitable base metal having a banded structure, in order to generate a high rate of change in the internal energy of the base metal. This energy change depressed the transformation temperatures of the base metal and induced an allotropic phase transformation to occur therein. Specifically, prior to being deformed, the base metal is maintained at a fairly low temperature. The tooling, preferably rolls 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 heating transformation temperatures at surface regions and thereby causes to transform into equiaxed grains. If the heating rate is insufficient to raise the temperature of the core of the base metal, then the core will retain its banded cold worked structure.
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