Method and apparatus for selectively heating a workpiece subjected to low temperature thermomechanical processing
First Claim
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1. A method for forming and heat treating a ferrous workpiece comprising the sequential steps of:
- a) preheating said workpiece to a predetermined temperature above the Ms temperature by any means;
b) inductively heating the surface of said workpiece by a coil energized at a radio frequency to a second predetermined temperature which is higher than said first temperature and sufficient to permit plastic deformation of said surface;
c) mechanically forming the surface of said workpiece by a shaping tool below said surface temperature of said workpiece drops below a temperature whereat said workpiece cannot be plastically deformed; and
,d) then quenching said workpiece.
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Abstract
Process and apparatus are provided for selective heating a portion of a workpiece to achieve improved ausforming and isoforming processes when the workpiece is plastically deformed by mechanical working above the Ms temperature. The process and apparatus includes a preheating step where a larger portion of the workpiece is preheated to less than the austenitic critical temperature while the final heating step conducted at a temperature higher than the austenitic critical temperature heats a smaller portion of the workpiece which is subsequently subjected to plastic deformation.
7 Citations
6 Claims
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1. A method for forming and heat treating a ferrous workpiece comprising the sequential steps of:
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a) preheating said workpiece to a predetermined temperature above the Ms temperature by any means; b) inductively heating the surface of said workpiece by a coil energized at a radio frequency to a second predetermined temperature which is higher than said first temperature and sufficient to permit plastic deformation of said surface; c) mechanically forming the surface of said workpiece by a shaping tool below said surface temperature of said workpiece drops below a temperature whereat said workpiece cannot be plastically deformed; and
,d) then quenching said workpiece. - View Dependent Claims (2)
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3. A method for forming and heat treating a ferrous workpiece comprising the sequential steps of:
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a) inductively heating a selected surface area of said workpiece; and b) plastically deforming said surface area by mechanical deformation while said workpiece exposed to ambient atmosphere rapidly drops in temperature. - View Dependent Claims (4, 5)
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6. Apparatus for forming and heat treating a ferrous workpiece comprising the sequential steps of:
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a) preheating means for preheating by any form of heat transfer said workpiece to a predetermined temperature above the Ms temperature of said workpiece; b) means for inductively heating the surface of said workpiece by a coil energized at a radio frequency to a second predetermined temperature which is higher than said first temperature; c) shaping means for mechanically forming the surface of said workpiece by shaping tool before said surface temperature of said workpiece drops below a temperature whereat said workpiece cannot be plastically deformed; and d) quench means for quenching said workpiece.
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Specification