Method for heat treating thick-walled forgings

Abstract

A method for heat treating thick-walled forgings including heating a low alloy steel to an austenitizing temperature, wherein the low alloy steel comprises carbon of about 0.05-0.2 wt. %, manganese of about 0.3-0.8 wt. %, and nickel of about 0.25-1.0 wt. %. The method further includes quenching the low alloy steel in a quench media, and then tempering the low alloy steel for less than about thirty minutes per inch of critical section thickness plus about two hours.

1 . A method for heat treating thick-walled forgings, the method comprising: 
 heating a low alloy steel to an austenitizing temperature, wherein the low alloy steel comprises carbon of about 0.05-0.2 wt. %, manganese of about 0.3-0.8 wt. %, and nickel of about 0.25-1.0 wt. %;    quenching the low alloy steel in a quench media; and    tempering the low alloy steel for less than about thirty minutes per inch of critical section thickness plus about two hours.    
     
     
         2 . The method of  claim 1 , wherein the low alloy steel further comprises phosphorus of greater than 0 up to about 0.04 wt. %, sulfur of greater than 0 up to about 0.04 wt. %, silicon of greater than 0 up to about 0.5 wt. %, chromium of about 2.0-2.5 wt. %, and molybdenum of about 0.45-1.15 wt. %.  
     
     
         3 . The method of  claim 1 , wherein the low alloy steel comprises nickel of about 0.5-1.0 wt. %.  
     
     
         4 . The method of  claim 1 , wherein the low alloy steel further comprises aluminum.  
     
     
         5 . The method of  claim 1 , wherein the low alloy steel further comprises vanadium.  
     
     
         6 . The method of  claim 1 , wherein the low alloy steel is calcium treated during a melting process.  
     
     
         7 . The method of  claim 1 , further comprising normalizing the low alloy steel prior to heating the low alloy steel to an austenitizing temperature.  
     
     
         8 . The method of  claim 1 , wherein the quench media is brine.  
     
     
         9 . The method of  claim 1 , wherein the finish temperature of the quench media is less than about 95 degrees Fahrenheit (35 degrees Celsius).  
     
     
         10 . A blowout preventer made using the method of  claim 1 .  
     
     
         11 . A forging comprising: 
 carbon of about 0.05-0.2 wt. %;    manganese of about 0.3-0.8 wt. %;    nickel of about 0.25-1.0 wt. %;    a cross-section thickness of at least about 8 inches;    an internal yield strength of greater than about 85 Ksi; and    a Brinell hardness value of at most about 237.    
     
     
         12 . The forging of  claim 11 , further comprising phosphorus of greater than 0 up to about 0.04 wt. %.  
     
     
         13 . The forging of  claim 1 , further comprising sulfur of greater than 0 up to about 0.04 wt. %.  
     
     
         14 . The forging of  claim 11 , further comprising silicon of greater than 0 up to about 0.5 wt. %.  
     
     
         15 . The forging of  claim 11 , further comprising chromium of about 2.0-2.5 wt. %.  
     
     
         16 . The forging of  claim 11 , further comprising molybdenum of about 0.45-1.15 wt. %.  
     
     
         17 . The forging of  claim 11 , further comprising an ultimate strength of at least about 100 Ksi.  
     
     
         18 . The forging of  claim 11 , further comprising an elongation of at least about 20%.  
     
     
         19 . The forging of  claim 11 , further comprising a reduction of area of at least about 70%.  
     
     
         20 . The forging of  claim 11 , further comprising a Brinell hardness value of at least about 217.