Root-cause Tree: Precipitate, Entrapped & Reaction Porosity
气孔根因树：析出、侵入与反应性
标签：气孔, 根因分析, 除气, 脱氧
气孔诊断先分三类再逐支排查：析出性——溶解氢随凝固析出，孔洞圆整、遍布断面，查炉料受潮与油污，浇前 700–750℃ 静态除气或吹氮 5–10 min；侵入性——型腔气体卷入，靠近表面沿型壁分布，查排气孔数量与涂料起皮；反应性——铜液中 Cu₂O 与氢反应生成水汽，孔壁发亮，锡青铜加磷铜 0.02–0.05% 脱氧。配合密度称重、断面位置图与浇温记录三件套，两三炉即可把废品率归因到具体工序。
Sort porosity into three families before diagnosing: precipitated — rounded holes scattered through the section from dissolved hydrogen; check damp or oily charge and degas statically at 700–750°C or nitrogen-bubble 5–10 min before pouring. Entrapped — mold gas near surfaces along the mold wall; check vents and peeling coatings. Reaction — Cu₂O plus hydrogen forming steam with shiny hole walls; deoxidize tin bronze with 0.02–0.05% phosphor-copper. Density weighing, defect-location maps and pour-temperature logs together pin the scrap to its true process step within a few melts.