Method for manufacturing a steel strip or sheet consisting mainly of mn-austenite

Abstract

The method according to the invention can be used for the economic manufacture of a steel strip (W) or sheet consisting mainly of Mn-austenite which possesses enhanced strength compared with the prior art. For this purpose a steel is melted which contains at least the following alloying components (in wt. %), 15.00-24.00% Cr, 5.00-12.00% Mn, 0.10-0.60% N, 0.01-0.2% C, max. 3.00% Al and/or Si, max. 0.07% P, max. 0.05% S, max. 0.5% Nb, max. 0.5% V, max. 3.0% Ni, max. 5.0% Mo, max. 2.0% Cu as well as iron and unavoidable impurities as the remainder. This steel is cast into a thin strip (D) having a maximum thickness of 10 mm in a casting gap formed between two rotating rollers ( 2, 3 ) or rolls. The rollers ( 2, 3 ) or rolls are cooled so intensively that the thin strip (D) in the casting gap ( 4 ) is cooled at a cooling rate of at least 200 K/s.

1 . Method for manufacturing a steel strip (W) or sheet consisting mainly of Mn-austenite, 
 in which a steel is melted which contains the following alloying constituents (in wt. %):                                            15.00-24.00% Cr,          5.00-12.00% Mn,          0.10-0.60% N,          0.01-0.2% C,         max. 3.00% Al and/or Si,         max. 0.07% P,         max. 0.05% S,         max. 0.5% Nb,         max. 0.5% V,         max. 3.0% Ni,         max. 5.0% Mo,         max. 2.0% Cu,         and iron and unavoidable impurities as the         remainder,                                                           and    in which the steel is cast in a casting gap formed between two rotating rollers ( 2 ,  3 ) or rolls into a thin strip (D) having a maximum thickness of 10 mm, whereby the rollers ( 2 ,  3 ) or rolls are cooled so intensively that the thin strip (D) in the casting gap ( 4 ) is cooled at a cooling rate of at least 200 K/s.    
     
     
         2 . Method according to  claim 1 , characterised in that the thickness of the thin strip (D) is 1 to 5 mm.  
     
     
         3 . Method according to one of the preceding claims, characterised in that the steel contains 17.00-21.00 wt. % Cr.  
     
     
         4 . Method according to one of the preceding claims, characterised in that the steel contains 8.00-12.00 wt. % Mn.  
     
     
         5 . Method according to one of the preceding claims, characterised in that the steel contains 0.40-0.60 wt. % N.  
     
     
         6 . Method according to one of the preceding claims, characterised in that the steel additionally contains Ni, Mo and/or Cu.  
     
     
         7 . Method according to one of the preceding claims, characterised in that the casting of the thin strip (D) takes place in a protective gas atmosphere.  
     
     
         8 . Method according to one of the preceding claims, characterised in that following the casting, the thin strip (D) is continuously hot-rolled to give a hot strip (W).  
     
     
         9 . Method according to  claim 8 , characterised in that before hot rolling the thin strip (D) is heated to an initial rolling temperature.  
     
     
         10 . Method according to  claim 9 , characterised in that the heating takes place under protective gas.  
     
     
         11 . Method according to one of  claims 8  to  10 , characterised in that after hot rolling the hot strip (W) is subjected to a heat treatment.  
     
     
         12 . Use of a steel strip manufactured according to one of  claims 1  to  11  as material for automobile-body sheet-metal parts.  
     
     
         13 . Use of a steel strip manufactured according to one of  claims 1  to  11  as material for stiffening structural components.  
     
     
         14 . Use of a steel strip manufactured according to one of  claims 1  to  11  as material for landing-gear or chassis parts.  
     
     
         15 . Use of a steel strip manufactured according to one of  claims 1  to  11  as material for vehicle wheels.  
     
     
         16 . Use of a steel strip manufactured according to one of  claims 1  to  11  as material for fuel tanks.