Tin-free, lead-free free-cutting magnesium brass alloy and its manufacturing method

Abstract

A tin-free lead-free free-cutting magnesium brass alloy comprises 56.0 to 64.0 wt % Cu, 0.6 to 2.5 wt % Mg, 0.15 to 0.4 wt % P and other elements 0.002 to 0.9 wt % which comprise at least two elements selected from the group consisting of Al, Si, Sb, Re, Ti and B and the balance being Zn with unavoidable impurities. The process for producing such alloy is also proposed. The invented alloy is excellent in cuttability, castability, hot and cold workability, corrosion resistance, mechanical properties and weldability and particularly applicable in spare parts, forging and casting which need cutting and grinding process. The cost of necessary metal materials of the invented alloy is lower than lead-free free-cutting bismuth and antimony brass alloy and is equivalent to lead-contained brass alloy.

1 . A lead-free free-cutting magnesium brass alloy comprising: 56.0 to 64.0 wt % Cu, 1.0 to 2.5 wt % Mg, 0.20 to 0.4 wt % P, and other elements 0.002 to 0.9 wt % which comprise at least two elements selected from the group consisting of Al, Si, Sb, Re, Ti and B and the balance being Zn with unavoidable impurities. 
   
   
       2 . The lead-free free-cutting magnesium brass alloy of  claim 1  wherein the content of P is between 0.20 to 0.3 wt % 
   
   
       3 . The lead-free free-cutting magnesium brass alloy of  claim 2  wherein the content of P is between 0.2 to 0.29 wt %. 
   
   
       4 . The lead-free free-cutting magnesium brass alloy of  claim 1  wherein the content of Mg is between 1.0 to 2.0 wt %. 
   
   
       5 . The lead-free free-cutting magnesium brass alloy of  claim 4  wherein the content of Mg is between 1.0 to 1.6 wt %. 
   
   
       6 . (canceled) 
   
   
       7 . The lead-free free-cutting magnesium brass alloy of  claim 5  wherein other elements are selected from Ti and B. 
   
   
       8 . The lead-free free-cutting magnesium brass alloy of  claim 1  wherein the content of other elements is between 0.003 to 0.8 wt %. 
   
   
       9 . The lead-free free-cutting magnesium brass alloy of  claim 8  wherein the content of other elements is between 0.003 to 0.05 wt %. 
   
   
       10 . (canceled) 
   
   
       11 - 14 . (canceled) 
   
   
       15 . The lead-free free-cutting magnesium brass alloy of  claim 1  wherein the cutting ratio percentage of said alloy is at least 85%. 
   
   
       16 . The lead-free free-cutting magnesium brass alloy of  claim 1  wherein the cutting ratio percentage of said alloy is at least 90%.