Systems, methods and devices for hot forming of steel alloy parts

Abstract

Disclosed are hot forming systems and apparatuses for metalworking components from micro-alloyed press hardened steel (PHS), methods for operating such systems/apparatuses, processes for hot forming components from micro-alloyed PHS, and components formed from such processes. A method of hot forming components from steel is disclosed. The method includes transferring a workpiece formed from a PHS micro-alloyed with niobium (e.g., 0.02-0.1 wt % Nb) to a furnace, e.g., via material handling robot. The workpiece is then heated to a peak furnace temperature and during a furnace time (e.g., total ramp and soak time) selected from a pentagon having heating time and temperature coordinates of: A (about 2 minutes, about 940° C.), B (about 2 minutes, about 1100° C.), C (about 3.5 minutes, about 1100° C.), D (about 5 minutes, about 975° C.), and E (about 5 minutes, about 940° C.). The heated workpiece is then transferred to a hot forming apparatus.

What is claimed: 
     
         1 . A method of hot forming a component from steel, the method comprising:
 transferring a workpiece to a furnace, the workpiece being formed from a press hardened steel alloyed with niobium (Nb);   heating the workpiece in the furnace to a furnace temperature and during a furnace time selected from a pentagon having heating time and temperature coordinates ABCDE of: A (about 2 minutes, about 940° C.), B (about 2 minutes, about 1100° C.), C (about 3.5 minutes, about 1100° C.), D (about 5 minutes, about 975° C.), and E (about 5 minutes, about 940° C.); and   transferring the heated workpiece from the furnace to a hot forming apparatus.   
     
     
         2 . The method of  claim 1 , wherein the press hardened steel is micro-alloyed with approximately 0.02 to 0.1 weight percent (wt. %) Nb. 
     
     
         3 . The method of  claim 2 , wherein the press hardened steel is micro-alloyed with approximately 0.05 wt. % Nb. 
     
     
         4 . The method of  claim 1 , wherein a final austenite grain size for the heated workpiece is approximately 10-40 microns. 
     
     
         5 . The method of  claim 1 , wherein a final austenite grain size for the heated workpiece is approximately 15 microns or less. 
     
     
         6 . The method of  claim 1 , wherein the furnace time includes heat ramp and soaking for a total furnace time of approximately 3 minutes, and the furnace temperature includes a heating rate of approximately 10° C./s to a peak furnace temperature of approximately 980° C. 
     
     
         7 . The method of  claim 1 , wherein the press hardened steel includes an aluminum silicon (AlSi) coating. 
     
     
         8 . The method of  claim 1 , wherein the press hardened steel includes a boron-alloyed press hardened steel. 
     
     
         9 . The method of  claim 8 , wherein the boron-alloyed quenched and tempered press hardened steel is 22MnB5 grade press hardened steel. 
     
     
         10 . The method of  claim 1 , further comprising:
 hot forming the heated workpiece via the hot forming apparatus; and   concurrent to the hot forming of the heated workpiece, cooling the workpiece in the hot forming apparatus at a predetermined cooling rate until a predetermined workpiece temperature is achieved,   wherein the predetermined cooling rate is not less than a critical cooling rate.   
     
     
         11 . The method of  claim 11 , wherein the predetermined workpiece temperature is between approximately 150 to 200° C., and wherein the critical cooling rate is not greater than 35 Kelvin per second. 
     
     
         12 . The method of  claim 1 , wherein the hot forming apparatus is a stamping press with a pair of opposing die, the method further comprising:
 hot stamping the heated workpiece in the die to form an intermediate workpiece; and   cooling the intermediate workpiece in the die at a predetermined cooling rate to form a final steel component.   
     
     
         13 . The method of  claim 12 , wherein the final steel component has a ductility of between approximately 6 to 12% and a tensile strength of approximately 1,800 megapascals (MPa) or greater. 
     
     
         14 . A metalworking system for hot forming a component from steel, the metalworking system comprising:
 a transfer device operable to transfer a workpiece between stations of the metalworking system, the workpiece being formed from a press hardened steel alloyed with niobium (Nb);   a furnace operable to receive the workpiece from the transfer device, the furnace being configured to heat the workpiece to a furnace temperature and during a furnace time selected from a pentagon having heating time and temperature coordinates ABCDE of: A (about 2 minutes, about 940° C.), B (about 2 minutes, about 1100° C.), C (about 3.5 minutes, about 1100° C.), D (about 5 minutes, about 975° C.), and E (about 5 minutes, about 940° C.); and   a hot forming apparatus operable to receive the heated workpiece from the furnace and mechanically deform the heated workpiece.   
     
     
         15 . A method of operating a metalworking system for hot forming a component from steel, the metalworking system including multiple metalworking stations, including a furnace and a hot forming apparatus, the method comprising:
 commanding a transfer device to transfer a workpiece to the furnace, the workpiece being formed from a press hardened steel alloyed with niobium (Nb);   commanding the furnace to heat the workpiece to a furnace temperature and during a furnace time selected from a pentagon having heating time and temperature coordinates ABCDE of: A (about 2 minutes, about 940° C.), B (about 2 minutes, about 1100° C.), C (about 3.5 minutes, about 1100° C.), D (about 5 minutes, about 975° C.), and E (about 5 minutes, about 940° C.);   commanding the transfer device to transfer the heated workpiece from the furnace to the hot forming apparatus; and   commanding the hot forming apparatus to mechanically deform the heated workpiece.   
     
     
         16 . The method of  claim 15 , wherein the press hardened steel is micro-alloyed with approximately 0.02 to 0.1 wt. % Nb. 
     
     
         17 . The method of  claim 15 , wherein a final austenite grain size for the heated workpiece is approximately 10-40 microns. 
     
     
         18 . The method of  claim 15 , wherein the press hardened steel includes a boron-alloyed press hardened steel. 
     
     
         19 . The method of  claim 15 , further comprising, concurrent to the hot forming apparatus mechanically deforming the heated workpiece, commanding the hot forming apparatus to cool the workpiece at a predetermined cooling rate until a predetermined workpiece temperature is achieved, wherein the predetermined workpiece temperature is between approximately 150 to 200° C., and wherein the critical cooling rate is not greater than 35 Kelvin per second. 
     
     
         20 . The method of  claim 19 , wherein the furnace time includes heat ramp and soaking for a total furnace time of approximately 3 minutes, and the furnace temperature includes a heating rate of approximately 10° C./s to a peak furnace temperature of approximately 980° C.