(廣東省材料與加工研究所，廣州 510650)
摘 要: 本文以自主設(shè)計的鎂合金油氣潤滑鑄造裝置制備了直徑154 mm的AZ80鎂合金鑄坯，系統(tǒng)研究油氣潤滑對AZ80鎂合金鑄坯表面質(zhì)量和凝固組織的影響，并對其機理進行了探討。采用結(jié)果表明：采用油氣潤滑鑄造時，氬氣和潤滑油在石墨環(huán)內(nèi)表面形成了一層油氣混合膜，改變了熔體和結(jié)晶器的接觸方式和熱交換狀態(tài)，從而制備出高品質(zhì)的AZ80鎂合金鑄坯。隨著氣體壓力的增加，鑄坯表面粗大的偏析瘤和皮下偏析層得到抑制，凝固組織得到了明顯細化。當(dāng)氣體壓力增加到0.4 MPa時，鑄坯皮下偏析層厚度從1252 μm降至628 μm，鑄坯R/2、心部晶粒尺寸和二次枝晶間距顯著減小。隨著凝固組織的細化，Al、Zn和Mn元素的宏觀偏析得到了改善。
關(guān)鍵字: AZ80鎂合金；油氣潤滑；半連鑄；表面質(zhì)量；凝固組織
（Guangdong Institute of Materials and Processing, Guangzhou 510650, China）
Abstract:AZ80magnesium alloy billets with diameter of 154 mm were prepared using oil-gas slip casting device designed in dependently. The effects of oil-gas slip on surface quality and solidification structure of AZ80 magnesium alloy billets were systematically studied and theoretically discussed. The results indicate that high quality AZ80 magnesium alloy billets can be prepared by oil-gas casting process. Argon and lubricating oil form an oil-gas film on the inner surface of the graphite ring, which changes the contact mode and thermo exchanging state between melt and graphite ring. With the increase of gas pressure, the coarse segregation tumors and the subsurface segregation layer on the billets surface are inhibited, and the solidification structure is refined obviously. When the gas pressure increases to 0.4 MPa, the thickness of subsurface segregation layer decreases from 1252 μm to 628 μm, and the grain size and secondary dendrite spacing at R/2 and center of the billets decrease significantly. Meanwhile, macrosegregation of Al, Zn and Mn elements is improved with the refinement of solidification structures.
Key words: AZ80 magnesium alloy; oil-gas slip; semi-continuous casting; surface quality; solidification structure
