Brass alloy

…the standard composition of copper alloys used as spring materials is 1.9% Be and 0.3% Co. Through age hardening, it exhibits the strongest strength of any practical copper alloy, comparable to special steel, and extremely excellent spring properties, making it an important material for high-quality springs.
[Brass-based alloy]
The main type is brass (also called shinchu), a copper-zinc alloy; those with up to 20% zinc are called red brass, and those with more than that are called brass. There are alloys with a wide range of zinc contents, but the main ones are 7-3 brass, which contains 30% zinc, 65-35 brass, which contains 35%, and 4-6 brass, which contains 35-45%. As the zinc content increases, the reddish color of the copper disappears, and the brass takes on a beautiful golden color.

*Some of the terminology that refers to "brass-based alloys" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ばね材料として使われるものの標準組成は1.9％Be,0.3％Coであって，時効硬化処理によって特殊鋼に匹敵する実用銅合金中最強の強度と，きわめて優れたばね特性を示し，高級なばね材料として重要な材料である。
［黄銅系合金］
　主体となるものは銅‐亜鉛合金の黄銅(シンチュウとも呼ばれる)で，とくに亜鉛が20％程度までのものを丹銅，それ以上を黄銅といい，亜鉛量の広い範囲にわたる合金があるが，おもなものは亜鉛30％を含む7‐3黄銅と，35％の65‐35黄銅，35～45％の4‐6黄銅である。亜鉛が増すにつれて銅の赤みがなくなり，黄銅は美しい黄金色を示す。…

※「黄銅系合金」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報