Flat steel semi-finished product, method for producing a component, and use thereof

Abstract

A semifinished flat steel product (1) includes a first layer (1.1) of a martensitic steel alloy having a tensile strength of >1200 MPa and/or a hardness of >370 HV10, and at least one second layer (1.2, 1.2′) of a soft steel alloy having a tensile strength of <600 MPa and/or a hardness of <190 HV10 which is fully and cohesively bonded to the first layer (1.1).

1 . A semifinished flat steel product comprising:
 a first layer ( 1 . 1 ) of a martensitic steel alloy having a tensile strength of >1200 MPa or a hardness of >370 HV10; and   at least one second layer of a soft steel alloy having a tensile strength of <600 MPa or a hardness of <190 HV10 which is fully and cohesively bonded to the first layer;   wherein:
 the first layer comprises, in % by weight:
 C: 0.15-0.6%; 
 Si: 0.05-0.9%; 
 Mn: 0.3-2.0%; 
 Al: 0.01-2.0%; 
 Cr+Mo: up to 1.5%; 
 Nb+Ti: up to 0.2%; 
 B: up to 0.02%; 
 V: up to 0.25%; 
 Cu: up to 0.2%; 
 Ni: up to 0.3%; 
 Sn: up to 0.05%; 
 Ca: up to 0.01%; 
 As: up to 0.02%; 
 N: up to 0.01%; 
 P: up to 0.06%; and 
 S: up to 0.03%; and 
 
 the second layer comprises, in % by weight;
 C: up to 0.2%; 
 Si: 0.01-0.6%; 
 Mn: 0.1-2.5%; 
 Al: 0.01-2.0%; 
 Cr+Mo: up to 1.4%; 
 Nb+Ti: up to 0.25%; 
 B: up to 0.02%; 
 V: up to 0.05%; 
 Cu: up to 0.2%; 
 Ni: up to 0.2%; 
 Sn: up to 0.05%; 
 Ca: up to 0.01%; Co: up to 0.02%; 
 N: up to 0.01%; 
 P: up to 0.1%; and 
 S: up to 0.06%. 
 
   
     
     
         2 . The semifinished flat steel product as claimed in  claim 1 , characterized in that the semifinished flat steel product has two second layers that are disposed on either side of the first layer and are fully and cohesively bonded thereto. 
     
     
         3 . The semifinished flat steel product as claimed in  claim 2 , characterized in that each of the second layers has a material thickness between 2% and 30%, based on the total material thickness of the semifinished flat steel product. 
     
     
         4 . The semifinished flat steel product as claimed in  claim 3 , characterized in that the semifinished flat steel product has an electrolytically applied zinc coating. 
     
     
         5 . The semifinished flat steel product as claimed in  claim 4 , characterized in that the semifinished flat steel product is produced by means of cladding or by means of casting. 
     
     
         6 . A process for producing a component for use in road vehicle construction, rail vehicle construction, shipbuilding or aerospace applications, wherein the component comprises a semifinished flat steel product as claimed in  claim 1 , and wherein the semi-finished flat steel product is cold-formed. 
     
     
         7 . The process as claimed in  claim 6 , characterized in that a cold forming operation for producing the cold-formed semi-finished flat product is effected by folding, U-O forming or roll profiling for production of a profile. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . The semifinished flat steel product as claimed in  claim 1 , characterized in that each of the second layers has a material thickness between 2% and 30%, based on the total material thickness of the semifinished flat steel product. 
     
     
         11 . The semifinished flat steel product as claimed in  claim 2 , characterized in that each of the second layers has a material thickness between 5% and 20%, based on the total material thickness of the semifinished flat steel product. 
     
     
         12 . The semifinished flat steel product as claimed in  claim 11 , characterized in that the semifinished flat steel product has an electrolytically applied zinc coating. 
     
     
         13 . The semifinished flat steel product as claimed in  claim 1 , characterized in that the semifinished flat steel product is produced by means of cladding or by means of casting. 
     
     
         14 . The semifinished flat steel product as claimed in  claim 2 , characterized in that the semifinished flat steel product is produced by means of cladding or by means of casting. 
     
     
         15 . The semifinished flat steel product as claimed  claim 3 , characterized in that the semifinished flat steel product is produced by means of cladding or by means of casting. 
     
     
         16 . The semifinished flat steel product as claimed in  claim 1 , characterized in that the semifinished flat steel product has an electrolytically applied zinc coating. 
     
     
         17 . The semifinished flat steel product as claimed in  claim 2 , characterized in that the semifinished flat steel product has an electrolytically applied zinc coating. 
     
     
         18 . The semifinished flat steel product as claimed in  claim 1 , characterized in that the semifinished flat steel product at least partly defines a component for use in road vehicle construction, rail vehicle construction, shipbuilding or aerospace applications. 
     
     
         19 . The semifinished flat steel product as claimed in  claim 18 , characterized in that the semifinished flat steel product is cold-formed. 
     
     
         20 . The semifinished flat steel product as claimed in  claim 19 , characterized in that a cold forming operation for producing the cold-formed semi-finished flat product is effected by folding, U-O forming or roll profiling for production of a profile. 
     
     
         21 . The semifinished steel product as claimed in  claim 1 , characterized in that the semifinished steel product is a battery housing of a vehicle. 
     
     
         22 . The semifinished steel product as claimed in  claim 1 , characterized in that the semifinished steel product is a seat rail of a vehicle seat.