Recipe: Annealing and Number of Folds
退火与折叠次数的配方
标签：退火节奏, 折叠次数, 厚度递减, 防裂配方, 黄铜参数
经验配方：每折叠锤压 2–3 次即需退火一次，紫铜加热至暗红（约 550°C）后入冷水淬火软化；黄铜同样温度但建议缓冷以减少应力。随折叠次数增加，板材有效厚度递减、鼓起量变小，一般 4–6 次折叠后形态已稳定，过多反而脆弱易裂。每次退火前清理氧化层以免夹渣。
Rule of thumb: anneal after every 2–3 hammer-fold cycles—heat copper to dull red (~550°C) and quench in water to soften; brass at the same temperature but cool slowly to reduce stress. Effective thickness drops with each fold and bulge shrinks; forms usually stabilise after 4–6 folds, beyond which the piece turns brittle. Descale before each anneal to avoid entrapped slag. ---