Invention Publication
- Patent Title: Process for Manufacturing a Press Hardened Laser Welded Steel Part
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Application No.: US18377943Application Date: 2023-10-09
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Publication No.: US20240035109A1Publication Date: 2024-02-01
- Inventor: Pascal Drillet , Maria Poirier , Sujay Sarkar
- Applicant: ArcelorMittal
- Applicant Address: LU Luxembourg
- Assignee: ArcelorMittal
- Current Assignee: ArcelorMittal
- Current Assignee Address: LU Luxembourg
- Priority: WO TIB2015001156 2015.07.09
- The original application number of the division: US17491785 2021.10.01
- Main IPC: C21D9/46
- IPC: C21D9/46 ; B32B15/01 ; C22C38/00 ; C22C38/02 ; C22C38/06 ; C22C38/26 ; C22C38/28 ; C22C38/32 ; C22C38/38 ; B21D22/02 ; C21D1/673 ; C21D8/02 ; C22C38/46 ; C22C38/44 ; C22C38/50 ; C22C38/54 ; C22C38/48 ; C22C21/02 ; B23K26/21 ; B21B1/22 ; C21D6/00 ; C22C38/22 ; C23C2/12

Abstract:
A process for manufacturing a press hardened laser welded steel part, includes providing at least one first steel sheet with a composition containing, by weight 0.062≤C≤0.095%, the at least one first steel sheet precoated with a metallic precoating of aluminum, or aluminum-based alloy, or aluminum alloy.
providing at least one second steel sheet with a composition containing, by weight, from to 0.38% of carbon, the at least one second steel sheet precoated with a metallic precoating of aluminum, or aluminum-based alloy, or aluminum alloy;
removing a portion of a thickness of the aluminum precoating at upper and lower sides along one side of a periphery of the at least one first steel sheet and the at least one second steel sheet;
creating a welded blank by laser welding the at least one first steel sheet and the at least one second steel sheet, such that an aluminum content in a weld metal is lower than 0.3% by weight, the laser welding being performed along the periphery wherein the portion of the thickness of the aluminum precoating has been removed;
heating the welded blank and holding the welded blank at a temperature Tm between 890 and 950° C., a holding duration Dm at the temperature being between 1 and 10 minutes, so as to obtain a heated welded blank;
transferring the heated welded blank within a forming press, the transfer duration Dt being less than 10 s;
hot forming the heated welded blank in the forming press so as to obtain a welded formed part; and
cooling the welded formed part at a first cooling rate CR1 between 40 and 360° C./s in a temperature range between 750 and 450° C., and at a second cooling rate CR2 between 15 to 150° C./s in a temperature range between 450° C. and 250° C., wherein CR2
providing at least one second steel sheet with a composition containing, by weight, from to 0.38% of carbon, the at least one second steel sheet precoated with a metallic precoating of aluminum, or aluminum-based alloy, or aluminum alloy;
removing a portion of a thickness of the aluminum precoating at upper and lower sides along one side of a periphery of the at least one first steel sheet and the at least one second steel sheet;
creating a welded blank by laser welding the at least one first steel sheet and the at least one second steel sheet, such that an aluminum content in a weld metal is lower than 0.3% by weight, the laser welding being performed along the periphery wherein the portion of the thickness of the aluminum precoating has been removed;
heating the welded blank and holding the welded blank at a temperature Tm between 890 and 950° C., a holding duration Dm at the temperature being between 1 and 10 minutes, so as to obtain a heated welded blank;
transferring the heated welded blank within a forming press, the transfer duration Dt being less than 10 s;
hot forming the heated welded blank in the forming press so as to obtain a welded formed part; and
cooling the welded formed part at a first cooling rate CR1 between 40 and 360° C./s in a temperature range between 750 and 450° C., and at a second cooling rate CR2 between 15 to 150° C./s in a temperature range between 450° C. and 250° C., wherein CR2
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