Toto Ltd.

Toru Uchida

Katsuaki Nakamura

Disclosed is a brass that possesses high corrosion resistance even without undergoing a heat treatment step contemplated for dezincification corrosion suppression. This brass includes 55% by mass to 75% by mass of Cu (copper), 0.01% by mass to 1.5% by mass of Si (silicon), Sn (tin) and Al (aluminum) in such amounts as to satisfy a prescribed relationship with an apparent Zn content, less than 0.25% by mass of Mn (manganese) as an optional ingredient, less than 0.05% by mass of Ti (titanium) as an optional ingredient, less than 0.3% by mass of Mg (magnesium) as an optional ingredient, less than 0.15% by mass of P (phosphorus) as an optional ingredient, and less than 0.004% by mass of a rare earth metal as an optional ingredient with the balance consisting of Zn (zinc) and unavoidable impurities, the apparent zinc content being 37 to 45.

Brass with excellent corrosion resistance

A brass free from lead and possessing excellent machinability, castability, mechanical properties, etc. consists of not less than 55% by weight and not more than 75% by weight of Cu, not less than 0.3% by weight and not more than 4.0% by weight of Bi, and y % by weight of B and x % by weight of Si, y and x satisfying the following requirements: 0&#x2264;x&#x2264;2.0, 0&#x2264;y&#x2264;0.3, and y&#x3e;&#x2212;0.15x+0.015ab, wherein a is 0.2 when Bi is 0.3% by weight&#x2264;Bi&#x3c;0.75% by weight; 0.85 when Bi is 0.75% by weight&#x2264;Bi&#x3c;1.5% by weight; and 1 when Bi is 1.5% by weight&#x2264;Bi&#x2264;4.0% by weight, b is 1 when the apparent content of zinc (Zn) is not less than 37% and less than 41%; and 0.75 when the apparent content of Zn is not less than 41% and not more than 45%, the balance consisting of Zn and unavoidable impurities.

Lead-free free-machining brass having improved castability

There is provided a brass free from lead (Pb) and possessing excellent machinability, castability, mechanical properties and other properties. A brass consisting of not less than 55% by weight and not more than 75% by weight of copper (Cu), not less than 0.3% by weight and not more than 4.0% by weight of bismuth (Bi), and y % by weight of boron (B) and x % by weight of silicon (Si), y and x satisfying the following requirements: 0&#x2266;x&#x2266;2.0, 0&#x2266;y&#x2266;0.3, and y&#x3e;&#x2212;0.15x+0.015ab, wherein a is 0.2 when Bi is 0.3% by weight &#x2266;Bi&#x3c;0.75% by weight; 0.85 when Bi is 0.75% by weight &#x2266;Bi&#x3c;1.5% by weight; and 1 when Bi is 1.5% by weight &#x2266;Bi&#x2266;4.0% by weight, b is 1 when the apparent content of zinc (Zn) is not less than 37% and less than 41%; and 0.75 when the apparent content of Zn is not less than 41% and not more than 45%, the balance consisting of Zn and unavoidable impurities, is excellent in castability, as well as, for example, in machinability and mechanical properties.

An object is to improve machinability and polishability of a brass material prepared through cold working, particularly in a brass pipe material. Before cold working, by having an &agr; phase making heat treatment step for increasing an area ratio of an &agr; phase, cold ductility can be ensured at the time of cold working. Also, after cold working, by having a &bgr; phase making heat treatment step for increasing an area ratio of a &bgr; phase, a brass material excellent in machinability and polishability can be provided.

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Fukuoka-ken, Japan

Toru Uchida