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1. (WO2007001374) METHOD OF MAKING HIGH STRENGTH FERROUS ARTICLE, AND ARTICLE MADE THEREBY
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CLAIMS
L A method for preparing a body of a ferrous alloy containing a high percentage of a preselected metallic phase, said method comprising the steps of:
providing a workpiece comprised of a ferrous alloy;
heating said workpiece to a temperature above an austenizing temperature of said alloy; and thereafter
contacting said workpiece with a quenching medium;
inputting heat to said workpiece during at least a portion of the time said workpiece is in contact with said quenching medium so that the combination of said heat which is input, and said quenching medium cooperate to maintain said workpiece at a preselected holding temperature which is above the martensite phase formation temperature of said alloy;
maintaining said workpiece at said holding temperature for a period of time sufficient to form a preselected metallic phase therein; and thereafter cooling the workpiece to an ambient temperature.

2. The method of claim 1, wherein said workpiece is held at a combination of said holding temperature and said time so as to form a bainite phase therein.

3. The method of claim 1, wherein said temperature is below 35O0C.

4. The method of claim 2, wherein said bainite phase is a lower bainite phase.

5. The method of claim 2, wherein said bainite phase is an upper bainite phase.

6. The method of claim 1, wherein the thickness of said workpiece is no greater than 5 millimeters.

7. The method of claim 1, wherein the thickness of said workpiece is no greater than 3 millimeters.

8. The method of claim 1, wherein the step of inputting heat to said workpiece comprises flowing an electrical current through said workpiece so as to resistively heat said workpiece.

9. The method of claim 1, wherein the step of heating said workpiece to a temperature above an austenizing temperature comprises flowing an electrical current through said workpiece so as to resistively heat said workpiece.

10. The method of claim 1, wherein the step of contacting said workpiece with a quenching medium comprises contacting said workpiece with a liquid medium.

11. The method of claim 1, wherein the step of contacting said workpiece with a quenching medium comprises contacting said workpiece with a gaseous quenching medium.

12. The method of claim 1, wherein the step of contacting said workpiece with a quenching medium comprises immersing said workpiece in said quenching medium.

13. The method of claim 1, wherein the step of contacting said workpiece with a quenching medium comprises spraying said quenching medium onto said workpiece.

14. The method of claim 1, including the further step of measuring the temperature of said workpiece while it is in contact with said quenching medium and said heat is being input thereinto.

15. The method of claim 13, including the further step of controlling the input of heat and/or a parameter of said quenching medium in response to the temperature of said workpiece.

16. The method of claim 1, wherein the step of inputting heat to said workpiece comprises inductively heating said workpiece.

17. The method of claim 1 , including the further step of carrying out a forming operation on said workpiece.

18. An article made by the method of claim 1.

19. An apparatus for preparing a body of a ferrous alloy having a high percentage of a preselected metallic phase, said system comprising:
a quenchant delivery system operable to deliver a quenchant fluid to a workpiece;
a heater operable to heat the workpiece during at least part of the time the quenchant delivery system is delivering said quenchant to the workpiece; and a controller for controlling at least one of said quenchant delivery system and said heater, so that said quenchant delivery system and said heater cooperate to maintain the workpiece at a preselected temperature which is above the martensite phase formation temperature of said alloy.

20. The apparatus of claim 17, further including a temperature sensor for generating a signal corresponding to the temperature of said workpiece, said temperature sensor being further operable to communicate said signal to the controller.