Annealing & Surface Cleaning
退火与表面清理
标签：退火, 清理, 酸洗, 氧化
退火消除加工硬化、恢复塑性：紫铜 400–600℃、黄铜 500–600℃ 保温后缓冷（可水冷）。铜退火时表面生成黑色氧化皮，可用稀酸（5–10% 硫酸或专用铜光亮剂）浸泡后水洗刷除，再用石英砂或钢丝绒抛光。注意：黄铜退火温度勿超 700℃，否则脱锌变脆。
Annealing removes work-hardening: copper 400–600℃, brass 500–600℃, hold then cool (water quench ok). Copper forms black scale — dip in dilute acid (5–10% sulfuric or brightener), rinse, brush, then polish with pumice/steel wool. Note: keep brass under 700℃ or it dezincifies and turns brittle. ---