(1. 北京科技大學 材料先進制備技術(shù)教育部重點實驗室，北京 100083； 2. 北京科技大學 現(xiàn)代交通金屬材料與加工技術(shù)北京實驗室，北京 100083)
摘 要: 研究熱冷組合鑄型(HCCM)水平連鑄H62 (UNS C27400)黃銅管坯外表面點狀缺陷的特點和形成機理，提出消除點狀缺陷的措施。結(jié)果表明：管坯外表面點狀缺陷主要為富鋅低熔點物質(zhì)，其鋅含量達80%(質(zhì)量分數(shù))；點狀缺陷的出現(xiàn)沿連鑄方向呈周期性特征，管坯上部的點狀缺陷數(shù)量明顯多于下部的；連鑄過程中，揮發(fā)的鋅在冷型內(nèi)表面形成的鋅液滴與管坯外表面接觸后發(fā)生熔蝕反應，使管坯外表面形成富鋅的點狀缺陷；通過快速降低冷型段內(nèi)管坯溫度，減少鋅元素揮發(fā)及石墨鑄型內(nèi)表面鋅液滴的形成，可有效消除點狀缺陷。
關鍵字: HCCM水平連鑄；黃銅管坯；富鋅物質(zhì)；表面缺陷；形成機理
（1. Key Laboratory for Advanced Materials Processing, Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China; 2. Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The characteristic and formation mechanism of spot defect on the outer surface of H62 (UNS C27400) brass tube fabricated by HCCM horizontal continuous casting were studied, and an effective method for eliminating the defect was proposed. The results show that the spot defect on the tube outer surface is main zinc-rich low-melting-point substance, whose zinc content (mass fraction) reaches 80%. The spot defects are periodically formed along the casting direction and the number of the defects on the upper part of the tube is much more than that on the lower part. During casting, the volatilized zinc attaches to the graphite mold inner surface and forms zinc droplets which causes an erosion effect on the tube surface when the zinc droplets contact with the tube, leading to the formation of the zinc-rich spot defect on the tube surface. A method of rapidly lowering the temperature of the solidified tube in the cold mold, which can reduce the zinc volatilization and the number of the zinc droplets on the inner surface of the mold, is proposed to eliminate the spot defects effectively.
Key words: HCCM horizontal continuous casting; brass tube; zinc-rich substance; surface defect; formation mechanism
