Steel for production of high-strength components with excellent low-temperature toughness and uses of a steel of this type

Abstract

The invention provides a high-strength steel that has excellent ductile fracture values J integral even at low temperatures, so the risk of the component, which is produced in each case from the steel, breaking is reduced to a minimum even under unfavourable, hard operating conditions. This is achieved in that it contains (in % by weight) 0.08 to 0.25% C, 0.10 to 0.30% Si, 0.80 to 1.60% Mn,=0.020% P,=0.015% S, the sum of the P and S content being=0.030%, 0.40 to 0.80% Cr, 0.30 to 0.50% Mo, 0.70 to 1.20% Ni, 0.020 to 0.060% Al, 0.007 to 0.018% N,=0.15% V,=0.07% Nb, the sum of the V and Nb content being=0.020% and the remainder being iron and inevitable impurities. The steel according to the invention is particularly suitable for the manufacture of high-strength chains.

1 . Steel for the production of high-strength components with excellent low-temperature toughness, having the following composition (in % by weight): 
 C: 0.08 to 0.25%,    Si: 0.10 to 0.30%,    Mn: 0.80 to 1.60%,    P:=0.020%,    S:=0.015%,    the sum of the P and S content being=0.030%,    Cr: 0.40 to 0.80%,    Mo: 0.30 to 0.50%,    Ni: 0.70 to 1.20%,    Al: 0.020 to 0.060%,    N: 0.007 to 0.018%,    V:=0.15%,    Nb:=0.07%,    the sum of the V and Nb content being=0.020%, the remainder being iron and inevitable impurities.    
   
   
       2 . Steel according to  claim 1 , wherein its C content is from 0.16% by weight to 0.23% by weight.  
   
   
       3 . Steel according to  claim 1 , wherein its Mn content is from 1.00% by weight to 1.35% by weight.  
   
   
       4 . Steel according to  claim 1 , wherein its Cr content is from 0.40% by weight to 0.65% by weight.  
   
   
       5 . Steel according to  claim 1 , wherein its Mo content is from 0.35% by weight to 0.50% by weight.  
   
   
       6 . Steel according to  claim 1 , wherein its Ni content is from 0.75% by weight to 1.00% by weight.  
   
   
       7 . Steel according to  claim 1 , wherein its Al content is from 0.020% by weight to 0.045% by weight.  
   
   
       8 . Steel according to  claim 1 , wherein its N content is from 0.007% by weight to 0.015% by weight.  
   
   
       9 . Steel according to  claim 1 , wherein it has an austenite grain size that is finer than ASTM 10.  
   
   
       10 . Use of a steel composed according to  claim 1  for the production of high-strength components by cold forming with subsequent temper-hardening.  
   
   
       11 . Use according to  claim 10 , wherein the components are means for the carrying, pulling, lifting, conveying or securing of loads.  
   
   
       12 . Use according to  claim 10 , wherein the components are means for the connection of structural elements.  
   
   
       13 . Use according to  claim 10 , wherein the components are chains.  
   
   
       14 . Use according to  claim 13 , Wherein the chains are round steel chains.  
   
   
       15 . Use according to  claim 13 , wherein the chains are welded.  
   
   
       16 . Use according to  claim 10 , wherein the components have a strength of at least 1,200 MPa.  
   
   
       17 . Use according to  claim 16 , wherein the strength is at least 1,550 MPa.  
   
   
       18 . Use according to  claim 16 , wherein the strength is at least 1,600 MPa, in particular at least 1,650 MPa.  
   
   
       19 . Use according to  claim 10 , wherein at a strength of at least 1,550 MPa, the fracture appearance transition temperature FATT of the components is at most −60° C.  
   
   
       20 . Use according to  claim 10 , wherein the notch impact working value is more than 45 J.  
   
   
       21 . Use according to  claim 10 , wherein the material of the component has a technical crack initiation toughness J IC  of more than 170 N/mm 2 .  
   
   
       22 . Use according to  claim 21 , wherein the technical crack initiation toughness J IC  is more than 185 N/mm 2 .  
   
   
       23 . Use according to  claim 10 , wherein the components exhibit an elongation at break of more than 28%.