Lead-free brass alloy

Abstract

The invention relates to a lead-free brass alloy containing the following components in percentage by weight: 0.3%-0.8% of aluminum, 0.01%-0.4% of bismuth, 0.05%-0.15% of ferrum and more than 96% of copper and zinc, wherein the copper content of the lead-free brass alloy is 58%-75%. The brass not only accords with the standard of the lead-free alloy environmental protection laws and regulations that the lead content is less than 0.25%, but also contains 0.05%-1.5% of ferrum and less than 0.4% of bismuth, so that the production cost can be reduced, the defects of cracks, slag inclusion and the like existing in castings can also be reduced, and therefore, the yield and the qualified rate of the product are effectively improved.

Description

technical field [0001] The invention relates to a brass alloy, in particular to a lead-free brass alloy with a lead content of less than 0.25% by weight. Background technique [0002] The main components of brass are copper and zinc, usually in a ratio of about 7:3 or 6:4, and usually contain a small amount of impurities. In order to improve the properties of brass, the known brass often contains 1 to 3% lead by weight to achieve the mechanical properties required by the industry, and thus become an important material in industry, widely used in metals for pipelines, faucets, water supply / drainage systems Devices or metal valves and other products. [0003] However, with the rise of environmental protection awareness, the impact of heavy metals on human health and environmental pollution has gradually been paid attention to. Therefore, restricting the use of lead-containing alloys has become a current trend. Japan, the United States and other countries have successively re...

AI Technical Summary

Problems solved by technology

[0004] On the other hand, when the zinc content in the brass exceeds 20% by weight, the corrosion phenomenon of dezincification (dezincification) is prone to occur, especially when the brass is exposed to an environment with high chloride ions, such as seawater environment, the dezincification corrosion phenomenon will be accelerated happened

Dezincification will seriously damage the structure of the brass alloy, reduce the surface strength of the brass product, and even cause the brass tube to perforate, greatly shorten the service life of the brass product, and cause problems in application

[0005] In order to overcome the above problems of high lead content and dezincification, the industry continues to develop new copper alloy formulations, in addition to the necessary components of copper and zinc, such as Taiwan Patent TW 421674, US Patent US7,354,489, US 2007-0062615, US 2006 -0078458, US 2004-023441, and US2002-069942 teach lead-free copper alloy formulations with addition of silicon (Si) and other elements, but the above alloys still have the disadvantage of poor machinability

Chinese patent CN 10144045 discloses a lead-free copper alloy formula with aluminum, silicon, and phosphorus as the main alloying elements. Although the alloy can be used for casting, it has the disadvantage of poor machinability, and its processing efficiency is much lower than that of lead-containing brass, so it is not suitable for mass production

Chinese patents CN101285138 and CN 101285137 also disclose the formula of lead-free copper alloy with phosphorus added, but this kind of alloy is prone to defects such as cracks and slag inclusions when used for casting

[0006] 另一方面,美国专利US 7,297,215、US 6,974,509、US 6,955,378、US6,149,739、US 5,942,056、US 5,653,827、US 5,487,867、US 5,330,712、US2006-0005901、US 2004-0094243、US 5,637,160、US 2007-0039667等揭示添加 A brass alloy of bismuth (Bi), the content of bismuth in the above-mentioned alloy formulation ranges from about 0.5% by weight to 7% by weight, but the high amount of bismuth in the alloy is likely to cause defects such as cracks and slag inclusions on the surface of the casting, and The cost is too high, which is not conducive to commercialization

Chinese patent CN 101403056 discloses a lead-free brass alloy containing bismuth and manganese, but this alloy still has the disadvantage of excessively high bismuth content. However, if the bismuth content is reduced and the manganese content is increased, the hardness will increase, and it is not easy to break chips, and Poor machinability

In addition, the above-mentioned brass alloy formula still has disadvantages such as poor casting performance and material embrittlement.

Chinese patent CN101440445 discloses a lead-free free-cutting aluminum-brass alloy containing bismuth and zinc. The alloy contains a considerable proportion of tin. Although it can improve the machinability of lead-free brass, it still has the disadvantages of high hardness and unfavorable processing.

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