Method to achieve variable properties within a component using coating free press hardened steel

Abstract

A method to achieve variable properties of a component using a coating free press hardened steel comprises: transferring a blank of a coating free press hardened steel (CFPHS) material having base blank properties into a heating unit having multiple induction heating coils; heating the blank within the heating unit to create a modified blank having differing modified blank properties throughout the modified blank compared to base blank properties; moving the modified blank out of the heating unit into a die; and forming a shaped part by operation of the die creating a finished CFPHS part.

What is claimed is: 
     
         1 . A method to achieve variable properties of a vehicle component using a coating free press hardened steel (CFPHS), comprising:
 transferring a blank of a CFPHS material having base blank properties into a heating unit having multiple induction heating coils;   heating the blank within the heating unit to create a modified blank having differing modified blank properties throughout the modified blank compared to the base blank properties;   moving the modified blank out of the heating unit into a die; and   forming a shaped part by operation of the die creating a finished CFPHS part.   
     
     
         2 . The method of  claim 1 , further including tailoring mechanical and surface qualities of the finished CFPHS part using a localized heating. 
     
     
         3 . The method of  claim 2 , further including performing the localized heating employing one a uniform heating rate and a tailored or a variable heating rate to achieve a desired temperature profile. 
     
     
         4 . The method of  claim 2 , further including uniformly heating across the blank or in predetermined areas within the blank to enable a selective mechanical and surface property profile defining the modified blank. 
     
     
         5 . The method of  claim 1 , further including energizing the induction heating coils using a variable power supply having a variable frequency device. 
     
     
         6 . The method of  claim 5 , further including generating varying and localized current intensities within the heating unit and across the blank. 
     
     
         7 . The method of  claim 6 , further including:
 generating variable heating rates using the variable power supply; and   providing zoned hold temperatures for the blank.   
     
     
         8 . The method of  claim 7 , further including operating a multi-axis transfer device to manipulate the blank within the heating unit to create the modified blank. 
     
     
         9 . The method of  claim 1 , further including creating the CFPHS material by:
 incorporating carbon (C) in an alloy matrix having a C concentration greater than or equal to about 0.05 wt. % to less than or equal to about 0.35 wt. %;   including chromium (Cr) at a Cr concentration of greater than or equal to about 1 wt. % to less than or equal to about 9 wt. %;   providing silicon (Si) at a Si concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 2 wt. %;   including Manganese (Mn) at a Mn concentration of greater than or equal to about 0.5 wt. % to less than or equal to about 2.5 wt. %; and   providing a balance of iron (Fe).   
     
     
         10 . The method of  claim 9 , further including creating the CFPHS material by:
 including with the alloy matrix martensite greater than or equal to about 95 vol. %;   creating a surface oxide layer on the alloy matrix, the surface oxide layer being continuous, and having a thickness of greater than or equal to about 0.01 μm to less than or equal to about 10 μm; and   enriching with Cr and Si.   
     
     
         11 . A method to achieve variable properties of a component using a coating free press hardened steel (CFPHS), comprising:
 transferring a blank of a CFPHS material into a heating unit having multiple induction heating coils;   energizing the induction heating coils using a variable power supply;   generating varying and localized current intensities within the heating unit and across the blank by operating predetermined ones of the induction heating coils;   heating the blank within the heating unit to create a modified blank having differing modified blank properties throughout the modified blank compared to properties of the blank prior to transferring the blank into the heating unit; and   operating a multi-axis transfer device to manipulate the blank within the heating unit when heating the blank to create the modified blank.   
     
     
         12 . The method of  claim 11 , further including operating a variable frequency device together with the variable power supply. 
     
     
         13 . The method of  claim 11 , further including:
 moving the modified blank out of the heating unit into a die using the multi-axis transfer device; and   forming a shaped part including operating the die to create a finished CFPHS part.   
     
     
         14 . The method of  claim 13 , further including forming a shaped part by operation of the die creating a finished CFPHS part. 
     
     
         15 . The method of  claim 11 , further including tailoring mechanical properties of the modified blank via operation of the induction heating coils to achieve an austenitization temperature in at least one zone of the modified blank and heating the modified blank to sub-critical temperatures in areas other than the at least one zone to achieve tailored mechanical properties within the modified blank. 
     
     
         16 . The method of  claim 11 , further including:
 mitigating an edge effect of overheating risk of the modified blank by tuning a current input and a frequency input to the induction heating coils or controlling a distance from one coil of the multiple induction heating coils for heating; and   varying an energy into the induction heating coils to vary material properties throughout a modified blank thickness.   
     
     
         17 . The method of  claim 11 , further including tailoring an oxide layer of the CFPHS material to provide an optimal thickness ranging between a no oxide layer to a maximum allowable oxide layer in differing areas of the modified blank. 
     
     
         18 . A method to achieve variable properties of a component using a coating free press hardened steel (CFPHS), comprising:
 transferring a blank of a CFPHS material into a heating unit having multiple induction heating coils, the blank having one of multiple shapes including but not exclusive to: flat, rod, wire, coil and bar;   energizing the induction heating coils using a variable power supply;   generating varying and localized current intensities within the heating unit and across the blank by operating predetermined ones of the induction heating coils to create multiple induction heating patterns across the blank to achieve targeted zones of surface properties of the blank; and   completing heating of the blank within the heating unit to create a modified blank having differing modified blank properties throughout the modified blank compared to properties of the blank prior to transferring the blank into the heating unit.   
     
     
         19 . The method of  claim 18 , further including:
 operating a multi-axis transfer device to manipulate the blank within the heating unit during modification of the blank into the modified blank;   moving the modified blank out of the heating unit into a die; and   forming a shape of the modified blank defining a finished CFPHS material component in the die.   
     
     
         20 . The method of  claim 18 , further including:
 heating the blank within the heating unit from a room temperature up to a range including approximately 500° C. to approximately 950° C.; and   applying a heating rate of approximately 20° C./second up to approximately 500° C./second when heating the blank.