Machinable copper-based alloy and production method

Abstract

Alloys based on copper, nickel, tin and lead obtained by a method of continuous or semi-continuous casting, or static billet casting or sprayforming billet casting, and capable of spinodal hardening. The machinability index of the inventive alloys exceeds 80% relatively to standard ASTM C36000 brass and can even reach 90%.

1 . Production method of a metallic product composed of an alloy comprising between 1% and 20% by weight of Ni, between 1% and 20% by weight of Sn, between 0.5% and 2% of Pb, the remainder being constituted essentially of Cu, the method comprising: 
 a heat treatment comprising a step of heating and homogenizing said alloy,    determining a cooling speed sufficiently slow to prevent fissuring and sufficiently high to limit the formation of a two-phased structure,    followed by a cooling step at the determined speed.    
   
   
       2 . The method of  claim 1 , wherein said heat treatment is followed by a step of cold deformation by rolling, wire-drawing, stretch-forming or hammering.  
   
   
       3 . The method of  claim 1 , wherein said heat treatment is performed in a through-type furnace.  
   
   
       4 . Method according to  claim 1 , comprising an initial step of continuous casting followed by a hammering step or an initial step of static billet casting or a step of sprayforming billet casting, or a step of semi-continuous billet casting, followed by an extrusion step.  
   
   
       5 . The method of  claim 1 , wherein said heat treatment takes places at a temperature comprised between 690° C. and 920° C.  
   
   
       6 . The method of  claim 1 , wherein the transversal dimension of said metallic product during said heat treatment is comprised between 1 mm and 100 mm.  
   
   
       7 . The method of  claim 1 , wherein said cooling step of said heat treatment has a cooling speed comprised between 10° C./min and 24000° C./min or between 10° C./min and 4000° C./min or between 100° C./min and 1500° C./min.  
   
   
       8 . The method of  claim 1 , wherein said cooling step of said heat treatment has a cooling speed comprised between 100° C./min and 1000° C./min.  
   
   
       9 . The method of  claim 1 , comprising a step of wire-drawing or stretch-forming or hammering or rolling.  
   
   
       10 . The method of  claim 1 , comprising a step of spinodal hardening.  
   
   
       11 . The method of  claim 1 , wherein said alloy comprises between 6% and 8% of Ni, between 4% and 6% of Sn and between 0.5% and 2% of Pb.  
   
   
       12 . The method of  claim 1 , wherein said alloy comprises between 8% and 10% of Ni, between 5% and 7% of Sn and between 0.5% and 2% of Pb.  
   
   
       13 . The method of  claim 1 , wherein said alloy comprises between 14% and 16% of Ni, between 7% and 9% of Sn and between 0.5% and 2% of Pb.  
   
   
       14 . Product from the method of  claim 1.