Cold-formable chrome steel

Abstract

A cold-formable, corrosion-resistant chrome steel includes, by weight percent, 14% to 20% chromium, 0.005% to 0.05% carbon, up to 0.01% nitrogen, 0.2% to 0.6% silicon, 0.3% to 1.0% manganese, 0.1% to 1.0% molybdenum, up to 0.8% nickel, 0.2% to 1.0% copper, 0.15% to 0.65% sulfur, as well as separately or in combination 0.01% to 0.1% lead, 0.01% to 0.5% bismuth, 0.01% to 0.1% arsenic, 0.01% to 0.1% antimony, 0.005% to 0.08% of each of vanadium, titanium, niobium, and zirconium, 0.02% to 0.2% of each of selenium and tellurium, the remainder iron and incidental smelting-related impurities.

1 . A chrome steel alloy having a composition comprising, by weight percent, 
 14% to 20% chromium,    0.005% to 0.05% carbon,    up to 0.01% nitrogen,    0.2% to 0.6% silicon,    0.3% to 1.0% manganese,    0.1% to 1.0% molybdenum,    up to 0.8% nickel,    0.2% to 1.0% copper,    0.02% to 0.2% selenium    and in addition, separately or in combination    0.01% to 0.1% lead,    0.01% to 0.5% bismuth,    0.01% to 0.1% arsenic,    0.01% to 0.1% antimony,    0.005% to 0.08% vanadium,    0.005% to 0.08% titanium,    0.005% to 0.08% niobium,    0.005% to 0.08% zirconium,    0.1 5% to 0.65% sulfur,    up to 0.20% tellurium,    the remainder iron and incidental smelting-related impurities.    
   
   
       2 . The chrome steel alloy of  claim 1 , having, by weight percent, 
 14% to 18% chromium,    0.01% to 0.03% carbon,    up to 0.01% nitrogen,    0.03% to 0.5% silicon,    0.4% to 0.7% manganese,    0.1% to 0.6% molybdenum,    up to 0.5% nickel,    0.2% to 0.6% copper,    0.02% to 0.2% selenium,    and in addition, separately or in combination    0.01% to 0.05% lead,    0.01% to 0.3% bismuth,    0.01% to 0.05% arsenic,    0.01% to 0.05% antimony,    0.005% to 0.08% vanadium,    0.005% to 0.08% titanium,    0.005% to 0.08% niobium,    0.005% to 0.08% zirconium,    0.15 % to 0.65% sulfur,    0.01% to 0.2% tellurium,    the remainder iron and incidental smelting-related impurities.    
   
   
       3 . The chrome steel alloy of  claim 1 , satisfying the following condition  
         K 1=(% Ti+% V+% Nb+% Zr)/% C=3 to 12.  
   
   
       4 . The chrome steel alloy of  claim 1 , satisfying the following condition  
         K 2=(% S+3% Se+3% Te)/10(% C++% N)=1.5 to 3.5.  
   
   
       5 . The chrome steel alloy of  claim 1 , satisfying the following condition  
         K 3=% S/(% S+% Se+% Te)=0.68 to 0.98.  
   
   
       6 . A method of thermal treatment of a cold-formed chrome steel alloy according to  claim 1 , comprising the steps of: 
 cold-forming the steel at least once for a total deformation from 65% to 90%; and    annealing the steel for 30 to 60 minutes at a temperature from 750 to 1080° C.    
   
   
       7 . The method of  claim 6 , further comprising the step of cooling the steel from the annealing temperature down to a temperature of 700° C. at small energy supply over a period of 30 to 180 minutes.  
   
   
       8 . The method of  claim 7 , wherein the steel is cooled down to a temperature of 500° C.  
   
   
       9 . The method of  claim 7 , further comprising the step of maintaining the temperature of the steel during the cool-down at least once for 10 to 30 minutes at an approximately constant temperature value.  
   
   
       10 . The method of  claim 9 , wherein the steel is maintained at a constant temperature of 680° C.  
   
   
       11 . The method of  claim 7 , wherein in a final processing step, the steel is heated up to a maximum temperature of 450° C. for at least 30 minutes.  
   
   
       12 . A method of using a chrome steel alloy according to  claim 1  for producing an article to be machined with a cutting tool.  
   
   
       13 . The method of  claim 12 , wherein the cutting tool includes a micro-cutting tool.  
   
   
       14 . A method of using a chrome steel alloy according to  claim 1  for producing an article selected from the group consisting of printer nozzles, writing stylus, injection nozzles for chemical and electronic devices, spinnerets, and articles of small size with or without recesses.  
   
   
       15 . An article for industrial use having a feature size of 0.6 mm or less and being made from a chromium steel alloy having a composition according to  claim 1.