Copper alloy having excellent corrosion cracking resistance and dezincing resistance, and method for producing same

Abstract

A copper alloy having an excellent corrosion cracking resistance and an excellent dezincing resistance consists of: 58 to 66 wt % of copper (Cu); 0.1 to 0.8 wt % of Sn; 0.01 to 0.5 wt % of Si; at least one of 0.3 to 3.5 wt % of lead (Pb), 0.3 to 3.0 wt % of bismuth (Bi), 0.02 to 0.15 wt % of phosphorus (P), 0.02 to 3.0 wt % of nickel (Ni) and 0.02 to 0.6 wt % of iron (Fe) if necessary; and the balance being zinc (Zn) and unavoidable impurities, wherein the proportion of an alpha phase is 80 vol % or more. The apparent content of zinc (Zn) in the copper alloy is in the range of from 34 to 39 wt %.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention generally relates to a copper alloy and a method for producing the same. More specifically, the invention relates to a copper alloy having an excellent corrosion cracking resistance and an excellent dezincing resistance, in addition to characteristics of conventional brasses having an excellent machinability or cutting workability and an excellent recyclability, and a method for producing the same. [0003] 2. Description of the Prior Art [0004] Conventional brasses, such as free-cutting brass rods / bars (JIS C3604) and forging brass rods / bars (JISC3771), which are copper-zinc alloys containing lead (Pb), are widely used for metal parts for water lines and valve parts due to their excellent malleability, hot workability and cutting workability. In addition, the scraps of brasses can be easily provided due to the large amount of distribution, so that brasses have an excellent recyclability and are ...

AI Technical Summary

Benefits of technology

The present invention provides a copper alloy with excellent corrosion cracking resistance and dezincing resistance while maintaining the characteristics of conventional brasses. The alloy includes copper, tin, silicon, and zinc, with an apparent content of zinc ranging from 34 to 39 wt%. The alloy may also contain lead, bismuth, nickel, phosphorus, and iron in specific amounts to further enhance its properties. The method for producing the alloy involves preparing raw materials, casting the raw materials to form an ingot, hot working the ingot, cold or hot working the hot worked ingot, annealing the cold or hot worked ingot, and cooling the annealed ingot. The technical effects of the invention include improved durability and reliability of the copper alloy, as well as reduced costs and improved manufacturing efficiency.

Problems solved by technology

However, if conventional copper-zinc alloys are used in warm water in a corrosive water quality environment, the ionization tendency of zinc in a beta phase is strong to give the elution of zinc priority, so that they have a very low dezincing corrosion resistance.

In particular, brasses of an alpha-plus-beta phase, such as forging brass rods / bars (JIS C3771) and free-cutting brass rods / bars (JIS C3604), have an inferior stress corrosion cracking resistance.

In the method for adding the large amount of Sn to improve the dezincing resistance, the local coagulation time of brass increases with the increase of the amount of Sn, so that the inverse segregation of Sn occurs during forging to cause surface detects on an ingot and to damage hot workability in extrusion and so forth.

Therefore, there is a problem in that the yields of products are remarkably deteriorated.

In addition, Sn is more expensive than copper-zinc scraps, so that there is a problem in that the costs increase if the amount of Sn to be added is large.

However, there is a problem in that this method can not improve the stress corrosion cracking resistance of the alloy.