US2005269074A1PendingUtilityA1

Case hardened stainless steel oilfield tool

40
Individually held — no corporate assignee on recordPriority: Jun 2, 2004Filed: Jun 2, 2004Published: Dec 8, 2005
Est. expiryJun 2, 2024(expired)· nominal 20-yr term from priority
Inventors:Gregory B. Chitwood
C21D 1/06C23C 8/22C21D 1/78C22C 38/44C23C 8/60C21D 6/04C21D 6/002C22C 38/18
40
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Claims

Abstract

An oilfield tool comprising a body of high chromium, low carbon steel and a high hardness surface having a supersaturated level of carbon. The body may be manufactured from a Super 13Cr type stainless steel. The tool may be carburized to a supersaturated level providing a surface hardness of about 55 HRC to 62 HRC and have an effective case depth of at least 0.020 inch at which depth the hardness is 50 HRC. The tool body is heat treated to a body hardness of about 39 HRC. A surface of the tool may be surface coated, e.g. nitrided or borided. The tool may be an expansion cone and may be a variable diameter expansion cone.

Claims

exact text as granted — not AI-modified
1 . An oilfield tool, comprising: 
 a body comprising a high chromium low carbon steel alloy, and    a case at least partially supersaturated with carbon.    
   
   
       2 . An oilfield tool according to  claim 1 , wherein the steel alloy comprises from about 8% chromium to about 19% chromium.  
   
   
       3 . An oilfield tool according to  claim 1 , wherein the steel alloy comprises from about 13% chromium to about 19% chromium.  
   
   
       4 . An oilfield tool according to  claim 1 , wherein the steel alloy comprises less than about 0.10% carbon.  
   
   
       5 . An oilfield tool according to  claim 1 , Wherein the steel alloy comprises a super 13Cr type stainless steel.  
   
   
       6 . An oilfield tool according to  claim 1 , wherein the steel alloy comprises less than about 0.05% carbon.  
   
   
       7 . An oilfield tool according to  claim 1 , wherein the case comprises from about 0.1% carbon to more that about 0.7% carbon.  
   
   
       8 . An oilfield tool according to  claim 1 , wherein the case comprises from about 0.1% carbon to about 1.6% carbon.  
   
   
       9 . An oilfield tool according to  claim 1 , wherein the case carbon saturation varies from supersaturated at the surface of the tool to about 0.1% or less adjacent the body of the tool.  
   
   
       10 . An oilfield tool according to  claim 1 , wherein the case carbon saturation varies from about 1.6% at the surface of the tool to about 0.1% or less adjacent the body of the tool.  
   
   
       11 . An oilfield tool according to  claim 1 , wherein the case has an effective case depth of from about 0.020 inch to about 0.040 inch.  
   
   
       12 . An oilfield tool according to  claim 1 , wherein the case has a total case depth of from about 0.080 inch to about 0.140 inch.  
   
   
       13 . An oilfield tool according to  claim 1 , wherein the steel alloy comprises a martensitic microstructure.  
   
   
       14 . An oilfield tool according to  claim 1 , further comprising a surface coating on at least one surface.  
   
   
       15 . An oilfield tool according to  claim 14 , wherein the surface coating is selected from a nitride and a boride.  
   
   
       16 . An oilfield tool according to  claim 1 , wherein the tool comprises a completion tool.  
   
   
       17 . An oilfield tool according to  claim 1 , wherein the tool comprises an expansion cone.  
   
   
       18 . A method of making an oilfield tool, comprising: 
 forming the tool from a high chromium low carbon steel alloy, and    carburizing the tool to produce a case at least partially supersaturated with carbon on at least one surface of the tool.    
   
   
       19 . A method according to  claim 18 , further comprising further heat treating the tool after carburizing.  
   
   
       20 . A method according to  claim 19 , wherein the further heat treating comprises multiple heating and cooling steps.  
   
   
       21 . A method according to  claim 20 , wherein one of the cooling steps is a sub-zero cooling step.  
   
   
       22 . A method according to  claim 19 , wherein further heat treating comprises hardening.  
   
   
       23 . A method according to  claim 22 , wherein further heat treating comprises tempering.  
   
   
       24 . A method according to  claim 22 , wherein further heat treating comprises tempering after hardening.  
   
   
       25 . A method according to  claim 19 , wherein further heat treating comprises tempering.  
   
   
       26 . A method according to  claim 18 , further comprising using a gas carburizing process.  
   
   
       27 . A method according to  claim 18 , further comprising using a vacuum carburizing process.  
   
   
       28 . A method according to  claim 18 , further comprising nitriding at least one surface of the tool.  
   
   
       29 . A method according to  claim 28 , wherein nitriding occurs after carburizing.  
   
   
       30 . A method according to  claim 18 , further comprising boriding at least one surface of the tool.  
   
   
       31 . A method according to  claim 30 , wherein boriding occurs after carburizing.

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