Orange-peel and Grain Size in Planished Surfaces
打平面橘皮与晶粒度的关系
标签：橘皮, 晶粒度, 再结晶, 表面质量
打平后表面出现粗糙橘皮，根因常在晶粒过粗：0.8 mm 以下薄铜若退火超过 650 ℃ 或保温过久，晶粒长到 0.1 mm 以上，锤击时粗晶沿滑移面不均匀变形即显橘皮。对策是把最终退火降到 550–600 ℃、保温不超过 5 min 并空冷；若已粗晶，可冷轧减径 10–15% 后重新退火细化。经验标准：ASTM 晶粒度 6 级以上（平均晶粒约 45 μm）才能稳定获得缎面；批量生产建议每炉留样做低倍晶粒腐蚀检查。
Coarse orange-peel after planishing usually traces to oversized grains: sheet under 0.8 mm annealed above 650 °C or held too long grows grains past 0.1 mm, and hammering then deforms them unevenly along slip planes. Fix it by dropping the final anneal to 550–600 °C with no more than 5 min soak and an air cool; if grains have already grown, cold-reduce 10–15% and re-anneal to refine. Rule of thumb: ASTM grain size 6 or finer (about 45 μm) is needed for a reliable satin finish, and production lines should etch a sample from every furnace charge.