High-tensile manganese steel containing aluminium, method for producing a sheet-steel product from said steel and sheet-steel product produced according to this method

Abstract

A formable lightweight steel having improved mechanical properties and a high resistance to delayed hydrogen-induced cracking formation and hydrogen embrittlement includes the following elements (in wt. %): C 0.02 to ≤1.0; Mn 3 to 30; Si≤4; P max. 0.1; S max. 0.1; N max. 0.03; Sb 0.003 to 0.8, particularly advantageously to 0.5, as well as at least one or more of the following carbide-forming elements in the specified proportions (in wt. %): Al≤15; Cr>0.1 to 8; Mo 0.05 to 2; Ti 0.01 to 2; V 0.005 to 1; Nb 0.005 to 1; W 0.005 to 1; Zr 0.001 to 0.3; with the remainder being iron including the usual steel-accompanying elements, with the optional addition of the following elements, in wt. %: max. 5 Ni, max. 10 Co, max. 0.005 Ca, max. 0.01 B and 0.05 to 2 Cu.

What is claimed is: 
     
         1 .- 15 . (canceled) 
     
     
         16 . A high-strength, aluminium-containing manganese steel comprising a following chemical composition in wt. %:
 C: 0.01 to <0.3   Mn: 4 to <10   Al: >1 to 4   Si: 0.01 to 1   Cr: 0.1 to 4   Mo: 0.02 to 1   P: <0.1   S: <0.1   N: <0.3   with the remainder being iron with unavoidable steel-associated elements.   
     
     
         17 . The steel of  claim 16 , further comprising at least one alloying element, in wt. %, selected from the group consisting of:
 V: 0.01 to 1   Nb: 0.01 to 1   Ti: 0.01 to 1   Sn: 0 to 0.5   Cu: 0.005 to 3   W: 0.03 to 3   Co: 0.05 to 3   Zr: 0.03 to 0.5   Ca: 0.0005 to 0.1.   
     
     
         18 . The steel of  claim 16 , wherein a content of Si is 0.01 to <1. 
     
     
         19 . The steel of  claim 16 , wherein a content of V is 0.02 to 1. 
     
     
         20 . The steel of  claim 16 , wherein a content of Nb is 0.02 to 1. 
     
     
         21 . The steel of  claim 16 , wherein a content of Ti is 0.02 to 1. 
     
     
         22 . The steel of  claim 16 , wherein a content of Sn is 0.005 to 0.5. 
     
     
         23 . The steel of  claim 16 , wherein a content of Cu is 0.5 to 3. 
     
     
         24 . The steel of  claim 16 , wherein a content of W is 0.05 to 3. 
     
     
         25 . The steel of  claim 16 , wherein a content of Co is 0.08 to 3. 
     
     
         26 . The steel of  claim 16 , wherein a content of Zr is 0.05 to 0.5. 
     
     
         27 . The steel of  claim 16 , wherein the steel has a tensile strength Rm>800 to 1700 MPa and an elongation at fracture A50 of 6 to 45%. 
     
     
         28 . The steel of  claim 16 , wherein the steel has an elongation at fracture A50 of >8 to 45%. 
     
     
         29 . A method for producing a flat steel product, comprising:
 smelting a steel melt having a chemical composition comprising in wt. %:   C: 0.01 to <0.3   Mn: 4 to <10   Al: >1 to 4   Si: 0.01 to 1   Cr: 0.1 to 4   Mo: 0.02 to 1   P: <0.1   S: <0.1   N: <0.3   with the remainder being iron with unavoidable steel-associated elements;   casting the steel melt to form a pre-strip by a horizontal or vertical strip casting process approximating a final dimension or casting the steel melt to form a slab or thin slab by a horizontal or vertical slab or thin slab casting process;   re-heating the slab or thin slab to 1050° C. to 1250° C. and then hot rolling the slab or thin slab to form a hot strip or thick plate, or re-heating the pre-strip which approximates the final dimension to 1000° C. to 1200° C. and then hot rolling the pre-strip to form a hot strip or thick plate, or hot rolling the pre-strip without re-heating from the casting heat to form a hot strip or thick plate with optional intermediate heating between individual rolling passes of the hot rolling;   reeling the hot strip and optionally the thick plate at a reeling temperature between 780° C. and room temperature;   optionally annealing the hot strip or thick plate at an annealing temperature of 610 to 780° C. and annealing duration of 1 minute to 48 hours;   optionally cold rolling the hot strip or produced pre-strip which approximates the final dimensions, with a thickness of less than or equal to 3 mm to form a cold strip;   optionally annealing the cold strip at an annealing temperature of 610 to 780° C. and annealing duration of 1 minute to 48 hours.   
     
     
         30 . The method of  claim 29 , wherein the steel melt contains at least one alloying element in wt. % selected from the group consisting of:
 V:0.01 to 1   Nb: 0.01 to 1   Ti: 0.01 to 1   Sn: 0 to 0.5   Cu: 0.005 to 3   W: 0.03 to 3   Co: 0.05 to 3   Zr: 0.03 to 0.5   Ca: 0.0005 to 0.1.   
     
     
         31 . The method of  claim 29 , wherein the produced pre-strip has a thickness of greater than 3 mm. 
     
     
         32 . The method of  claim 29 , wherein the slab is hot-rolled to form a hot strip having a thickness of 70 mm to 1.5 mm or the pre-strip is hot rolled to form a hot strip having a thickness of 8 mm to 1 mm. 
     
     
         33 . A flat steel product produced by a method as set forth in  claim 29 , said steel product comprising a tensile strength Rm of >800 to 1700 MPa, and an elongation at fracture A50 of 6 to 45%. 
     
     
         34 . The steel product of  claim 33 , wherein the steel product has an elongation at fracture A50 of >8 to 45%. 
     
     
         35 . The steel product of  claim 33 , wherein the steel product is galvanised by hot-dipping or electrolytically or is coated metallically, inorganically or organically.