Silicon bismuth lead-free casting brass alloy and preparing method thereof

Abstract

The invention relates to a silicon bismuth lead-free casting brass alloy and a preparing method thereof. The brass alloy comprises, by mass percent, 61 to 67% of Cu, 0.5 to 1.0% of Bi, 0.8 to 1.25% of Si, 0.3 to 0.7% of Al, 0.05 to 0.3% of Sn, smaller than 0.01% of Pb, not larger than 0.002% of B, not larger than 0.008% of Ti, not larger than 0.01% of a rare earth modifier (at least comprising three of Nd, Eu, Er, Y, Zr and the like) and the balance Zn and smaller than 0.3% of impurities. Bi / Si is larger than or equal to 0.4 and smaller than or equal to 1.1.

Description

technical field [0001] The invention relates to the technical field of alloys, in particular to a silicon-bismuth lead-free cast brass alloy and a preparation method thereof. Background technique [0002] The wide application of lead brass (common grade HPb59-1) in the field of wading copper alloy products is based on the combined effect of many factors such as material composition optimization, preparation process optimization and manufacturing process level improvement for a long time. Lead brass will pollute the environment and endanger human health in the process of production and use. The harm of lead has been deeply rooted in the hearts of the people and has far-reaching effects. Therefore, developed countries and regions such as the United States, the European Union, and Japan have successively formulated a series of "lead-free" standards and laws, such as NSF-ANSI61, NSF-ANSI372, AB-1953, RoHS, AS / NZS, S3874, etc. Among them, the S3874 lead-free act of the United S...

AI Technical Summary

Problems solved by technology

However, when the alloy uses the zinc equivalent to calculate the alloy phase composition, it uses the wrong zinc equivalent formula (the denominator part is obviously wrong), which makes the composition optimization results unreliable

In addition, using the metallographic micrographs provided by the patent to calculate, the matrix grain size is quite coarse (at least greater than 300 μm), which cannot reflect the effect of grain refinement at all.

According to the basic knowledge of materials science, coarse grains will directly lead to the deterioration of the mechanical properties and molding properties of the material, and it is difficult to reflect the performance improvement effect mentioned in the patent

In the preparation process, the copper and copper-silicon intermediate alloys are completely melted (1050-1100°C) and then cooled to 400-700°C to add aluminum ingots and zinc ingots sequentially, which is obviously energy-consuming and expensive.

[0009] In summary, although some schemes in the existing above-mentioned technical schemes claim to prepare lead-free brass, there is a phenomenon of deliberately adding lead elements; in some schemes, the high melting point alloy elements (such as: Si) are mostly in the form of master alloys ( Such as: Cu-Si alloy) is added, although the composition ratio is relatively well regulated, but the cost is high; in some schemes, the low melting point components are often added when the high temperature melt is lowered to a lower temperature, and the energy consumption is serious.

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