Steel composition and parts forged by a forging die

Abstract

The invention relates to a steel composition, comprising the following components: C; 0.12-0.45 wt. % Si; 0.10-1.00 wt. % Mn; 0.50-1.95 wt. % S; 0.005-0.060 wt. % Al; 0.004-0.050 wt. % Ti; 0.004-0.050 wt. % Cr; 0-0.60 wt. % Ni; 0-0.60 wt. % Co; 0-0.60 wt. % W; 0-0.60 wt. % B; 0-0.01 Mo; 0-0.60 wt. % Cu; 0-0.60 wt. % Nb; 0-0.050 wt. % V; 0.10-0.40 wt. % N; 0.015-0.040 wt. % remaining: Fe and unavoidable impurities with the proviso that: 1) wt. % V×wt. % N=0.0021 0.0120 2) 1.6×wt. % S+1.5×wt. % Al+2.4×wt. % Nb+1.2×wt. % Ti=0.035 0.140 3) 1.2×wt. % Mn+1.4×wt. % Cr+1.0×wt. % Ni+1.1×wt. % Cu+1.8×wt. % Mo=1.00 3.50. The steel composition is highly suitable for use in the production of highly resistant, highly tenacious parts forged by a forging die without terminal quenching, which can be used as chassis parts for passenger cars and commercial vehicles.

1 . A steel composition, characterized in that it comprises the following components in % by weight: 
 C: 0.12-0.45    Si: 0.10-1.00    Mn: 0.50-1.95    S: 0.005-0.060    Al: 0.004-0.050    Ti: 0.004-0.050    Cr: 0-0.60    Ni: 0-0.60    Co: 0-0.60    W: 0-0.60    B: 0-0.01    Mo: 0-0.60    Cu: 0-0.60    Nb: 0-0.050    V: 0.10-0.40    N: 0.015-0.040    Remainder: Fe and unavoidable impurities    with the proviso that:    1) wt % V×wt % N=0.0021 to 0.0120    2) 1.6×wt % S+1.5×wt % Al+2.4×wt % Nb+1.2×wt % Ti=0.035 to 0.140    3) 1.2×wt % Mn+1.4×wt % Cr+1.0×wt % Ni+1.1×wt % Cu+1.8×wt % Mo=1.00 to 3.50    
     
     
         2 . A die-formed part made of steel, characterized in that the steel has a composition according to  claim 1 .  
     
     
         3 . A method of producing a die-formed part according to  claim 2 , comprising the steps of: 
 (a) heating the ingoing material made of a steel composition according to  claim 1  to a temperature of 1,000 to 1,300° C.;    (b) forming the ingoing material of step (a) by forging;    (c) cooling the die-formed part obtained in step (b) to room temperature, wherein the cooling rate in the temperature range to 580° C. is at least 0.2° C./s.    
     
     
         4 . A method according to  claim 3 , characterized in that the cooling in step (c) occurs at a cooling rate of 0.2° C./s to 0.6° C./s until a temperature of 580° C.  
     
     
         5 . A method according to  claim 3 , characterized in that the cooling in step (c) occurs at a cooling rate of 0.7° C./s to 6° C./s until a temperature of 580° C.  
     
     
         6 . The use of the die-formed part obtainable by the method according to one of  claims 3  to  5  as a chassis part for commercial vehicles.  
     
     
         7 . The use of the die-formed part obtainable by the method according to  claim 5  as a chassis part for passenger cars.