——直徑0.2m錠坯的鑄態(tài)組織
(東北大學(xué) 材料電磁過程研究教育部重點(diǎn)實(shí)驗室， 沈陽 110004)
摘 要: 采用低頻電磁鑄造技術(shù)， 半連續(xù)鑄造制備了直徑為0.2m的7A60超高強(qiáng)鋁合金錠坯。 研究了鑄錠表面質(zhì)量和內(nèi)裂紋發(fā)生情況， 考察了電磁場頻率和強(qiáng)度對鑄態(tài)組織的影響。結(jié)果表明： 低頻電磁場可消除錠坯裂紋， 改善其表面質(zhì)量。 在低頻電磁場作用下， 半連續(xù)鑄造組織得到顯著細(xì)化， 鑄錠邊部和中間部位的晶粒大小差別減小， 其平均晶粒尺寸分別為30μm和45μm。 適當(dāng)降低電磁場頻率和增加強(qiáng)度有利于獲得細(xì)小均勻的等軸晶組織，鑄造組織最佳的電磁場頻率為25Hz， 安匝數(shù)為18000A·turn。
關(guān)鍵字: 低頻; 電磁鑄造; 微觀組織; 細(xì)化; Al-Zn-Mg-Cu-Zr
low frequency electromagnetic cast（Ⅰ）——as-cast structures of billets with diameter of 0.2m
ZHAO Zhi-hao， BAO Wei-ping
（Key Laboratory of Electromagnetic Processing of Materials for Ministry of Education, Northeastern University,
Shenyang 110004， China）
Abstract:Under the low frequency electromagnetic field, a super-high strength 7A60 Al alloy was semi-continuously cast into billets with diameter of 0.2m. The surface properties, inner cracks of billets and the effect of electromagnetic frequency and intensity on as-cast microstructures were investigated. The microstructures of 7A60 Al alloy cast under low frequency electromagnetic field are fine, uniform and equiaxed, the difference of the microstructures between the border and center of the billet is small, their average sizes are 30 and 45μm, respectively. The decrease of electromagnetic frequency and increase of intensity are helpful for obtaining fine, uniform and equiaxed as-cast microstructures. The optimum electromagnetic parameters are that the frequency is 25Hz and the number of ampere turns is 18000A·turn.
Key words: low frequency; electromagnetic cast; microstructure; refinement; Al-Zn-Mg-Cu-Zr
