Bainitic steel for rock drilling component

Abstract

A bainitic steel comprising, in weight % (wt %): C: 0.16-0.23, Si: 0.8-1.0, Mo: 0.67-0.9, Cr: 1.10-1.30, V: 0.18-0.4, Ni: 1.60-2.0, Mn: 0.65-0.9, P: ≦0.020, S: ≦0.02, Cu: <0.20, N: 0.005-0.012 balance Fe and unavoidable impurities.

1 . Bainitic steel comprising, in weight % (wt %):
 C: 0.16-0.23   Si: 0.8-1.0   Mo: 0.67-0.9   Cr: 1.10-1.30   V: 0.18-0.4   Ni: 1.60-2.0   Mn: 0.65-0.9   P: ≦0.020   S: ≦0.02   Cu: <0.20   N: 0.005-0.012 wt %   balance Fe and unavoidable impurities.   
     
     
         2 . The bainitic steel according to  claim 1 , wherein the amount of Si is 0.85-0.95 wt %. 
     
     
         3 . The bainitic steel according to  claim 1 , wherein the amount of Mo is 0.70-0.80 wt %. 
     
     
         4 . The bainitic steel according  claim 1 , wherein the amount of Cr is 1.20-1.25 wt %. 
     
     
         5 . The bainitic steel according  claim 1 , wherein the amount of V is 0.20-0.30 wt %, preferably 0.2-0.25 wt %. 
     
     
         6 . The bainitic steel according  claim 1 , wherein the amount of N is 0.008-0.012 wt %. 
     
     
         7 . A component for rock drilling comprising a bainitic steel comprising, in weight % (wt %):
 C: 0.16-0.23   Si: 0.8-1.0   Mo: 0.67-0.9   Cr: 1.10-1.30   V: 0.18-0.4   Ni: 1.60-2.0   Mn: 0.65-0.9   P: <0.020   S: <0.02   Cu: <0.20   N: 0.005-0.012 wt %   balance Fe and unavoidable impurities.   
     
     
         8 . The component according to  claim 7 , wherein the component is a threaded male or female connector for a drill rod. 
     
     
         9 . The component according to  claim 7 , wherein the component is a drill rod including a threaded male and a threaded female connector. 
     
     
         10 . A method for manufacturing a component for rock drilling comprising the steps of:
 a. forming a component for rock drilling, the component being a threaded male or female connector, in a steel comprising, in weight % (wt %):
 C: 0.16-0.23 
 Si: 0.8-1.0 
 Mo: 0.67-0.9 
 Cr: 1.10-1.30 
 V: 0.18-0.4 
 Ni: 1.60-2.0 
 Mn: 0.65-0.9 
 P: <0.020 
 S: <0.02 
 Cu: <0.20 
 N: 0.005-0.012 wt % 
   balance Fe and unavoidable impurities;   b. heating said component to an austenitizing temperature;   c. holding said component at the austenitizing temperature in a carbon containing atmosphere for a predetermined time; and   d. cooling said component.   
     
     
         11 . The method according to  claim 10 , wherein the component is heated to a temperature of 900-1000° C. 
     
     
         12 . The method according to  claim 10 , wherein the component is heated in an atmosphere of CO and H 2 . 
     
     
         13 . The method according to  claim 10 , wherein the component is heated for 3-6 hours. 
     
     
         14 . The method according to  claim 10 , wherein the component is cooled in air. 
     
     
         15 . The component according to  claim 7 , wherein the component is a case hardened connector for drill rods used during air-cold top hammer drilling above ground.