Highly corrosion-resistant copper tube

Abstract

A corrosion resistant copper tube which can exhibit a further improved resistance to ant nest corrosion, and which is suitably usable as a heat transfer tube and refrigerant tube in air-conditioning equipment and refrigerating equipment. The copper tube is formed of a copper material consisting of 0.15-0.6% by weight of phosphorus and the balance being copper and impurities, and has electric conductivity (Y1 or Y2: % IACS) which satisfies 50-75X≤Y1≤60-75X in the case where the tube includes a recrystallized structure, or 47-75X≤Y2≤57-75X in the case where the tube includes a deformation structure, wherein X (% by weight) represents a content of phosphorus.

1 . A highly corrosion-resistant copper tube formed of a copper material consisting of 0.15-0.6% by weight of phosphorus and the balance being copper and impurities, wherein the tube includes a recrystallized structure and has electric conductivity (Y1: % IACS) which satisfies the following formula:
   50-75X≤Y1≤60-75X
   
       wherein X (% by weight) represents a content of phosphorus. 
     
     
         2 . A highly corrosion-resistant copper tube formed of a copper material consisting of 0.15-0.6% by weight of phosphorus and the balance being copper and impurities, wherein the tube includes a deformation structure and has electric conductivity (Y2: % IACS) which satisfies the following formula:
   47-75X≤Y2≤57-75X
   
       wherein X (% by weight) represents a content of phosphorus. 
     
     
         3 . The highly corrosion-resistant copper tube according to  claim 1 , wherein a content of a group of specific impurity elements consisting of Cr, Mn, Fe, Co, Zr and Mo among the impurities is not higher than 0.01% by weight in total. 
     
     
         4 . The highly corrosion-resistant copper tube according to  claim 2 , wherein a content of a group of specific impurity elements consisting of Cr, Mn, Fe, Co, Zr and Mo among the impurities is not higher than 0.01% by weight in total. 
     
     
         5 . The highly corrosion-resistant copper tube according to  claim 3 , wherein a content of inevitable impurity elements other than the group of the specific impurity elements among said impurities is not higher than 0.005% by weight in total. 
     
     
         6 . The highly corrosion-resistant copper tube according to  claim 4 , wherein a content of inevitable impurity elements other than the group of the specific impurity elements among the impurities is not higher than 0.005% by weight in total. 
     
     
         7 . The highly corrosion-resistant copper tube according to  claim 1 , wherein the tube is arranged in a damp environment and subjected to corrosion that progresses in the form of an ants' nest from a surface of the tube in a direction of a wall thickness of the tube by a corrosive medium in the form of a lower carboxylic acid. 
     
     
         8 . The highly corrosion-resistant copper tube according to  claim 2 , wherein the tube is arranged in a damp environment and subjected to corrosion that progresses in the form of an ants' nest from a surface of the tube in a direction of a wall thickness of the tube by a corrosive medium in the form of a lower carboxylic acid. 
     
     
         9 . A process for producing a highly corrosion-resistant copper tube comprising:
 a step of providing a copper ingot consisting of 0.15-0.6% by weight of phosphorus and the balance being copper and impurities;   a step of heat-treating the copper ingot at a temperature of 750-950° C.;   a step of hot-extruding the heat-treated copper ingot at a temperature of 750-950° C. so as to obtain a copper tube;   a step of cold-working the copper tube by a drawing process and further a grooving process as necessary to form a desired size of copper tube; and   a step of subjecting the copper tube obtained by the cold working to final annealing so as to obtain the copper tube including a recrystallized structure and having electric conductivity (Y1: % IACS) which satisfies the following formula:
   50-75X≤Y1≤60-75X
 
   
       wherein X (% by weight) represents a content of phosphorus. 
     
     
         10 . The process for producing a highly corrosion-resistant copper tube according to  claim 9 , wherein the final annealing is performed at a temperature of 300-600° C. 
     
     
         11 . A process for producing a highly corrosion-resistant copper tube comprising:
 a step of providing a copper ingot consisting of 0.15-0.6% by weight of phosphorus and the balance being copper and impurities;   a step of heat-treating the copper ingot at a temperature of 750-950° C.;   a step of hot-extruding the heat-treated copper ingot at a temperature of 750-950° C. so as to obtain a copper tube; and   a step of cold-working the copper tube by a drawing process and further a grooving process as necessary to form a desired size of copper tube including a deformation structure and having electric conductivity (Y2: % IACS) which satisfies the following formula:
   47-75X≤Y2≤57-75X
 
   
       wherein X (% by weight) represents a content of phosphorus. 
     
     
         12 . The process for producing a highly corrosion-resistant copper tube according to  claim 9 , wherein the heat-treating step of the copper ingot is a homogenization process. 
     
     
         13 . The process for producing a highly corrosion-resistant copper tube according to  claim 11 , wherein the heat-treating step of the copper ingot is a homogenization process. 
     
     
         14 . The process for producing a highly corrosion-resistant copper tube according to  claim 9 , wherein the heat-treating of the copper ingot is a preliminary heat treatment performed in advance of the extrusion. 
     
     
         15 . The process for producing a highly corrosion-resistant copper tube according to  claim 11 , wherein the heat-treating of the copper ingot is a preliminary heat treatment performed in advance of the extrusion. 
     
     
         16 . A heat transfer tube for air-conditioning equipment or refrigerating equipment, consisting of the highly corrosion-resistant copper tube according to  claim 1 . 
     
     
         17 . A heat transfer tube for air-conditioning equipment or refrigerating equipment, consisting of the highly corrosion-resistant copper tube according to  claim 2 . 
     
     
         18 . A refrigerant tube for air-conditioning equipment or refrigerating equipment, consisting of the highly corrosion-resistant copper tube according to  claim 1 . 
     
     
         19 . A refrigerant tube for air-conditioning equipment or refrigerating equipment, consisting of the highly corrosion-resistant copper tube according to  claim 2 . 
     
     
         20 - 21 . (canceled)