Flame Coloring Copper-steel Assemblies
铜与钢/不锈钢拼接件的火焰着色
标签：拼接件, 不锈钢, 热传导, 遮蔽, 火焰
铜-钢拼接件火焰着色的两大难点：①导热差近 8 倍——铜侧 10 s 内到温，钢侧同点仍冷，接缝两侧色带错位；对策是铜侧先着色，钢侧边焰烤边用湿布或喷水雾背冷，把热锁在铜侧。②钢的回火色区间（230 °C 草黄、290 °C 蓝）与铜干涉色区间重叠但不一致，若需钢侧同色，须按钢的色-温曲线单独标定并缩短焰距。焊缝区宜用镍基焊材，普通铜焊料在钢侧焰烤时易过熔流挂，污染已完成的色面。
Two problems dominate copper-steel assemblies: (1) an ~8× conductivity gap — copper hits temperature in 10 s while adjacent steel stays cold, offsetting color bands across the seam; color the copper first and back-chill the steel with wet cloth or water mist to lock heat into the copper side. (2) Steel temper colors (straw ~230 °C, blue ~290 °C) overlap copper's interference band imperfectly — if the steel must match, calibrate against steel's own color-temperature curve with a shorter flame distance. Use nickel-based filler at welds: copper brazing alloys sag when the steel side is flamed and stain finished color.