pISSN : 1598-706X / eISSN : 2288-8381
한국주조공학회지 (31권6호 347-353)
The Effect of Ca Addition on the Grain Growth Inhibition During Reheating Process of Al-Zn-Mg Al Alloys for Thixo-extrusion
반응고 Al-Zn-Mg계 합금의 반용융 압출을 위한 재가열 시 결정립 성장 억제에 미치는 Ca 첨가의 영향
Hyung-Won Park, Dae-Hwan Kim, Sung-Yong Shim, Hee-Kyung Kim, Bong-Hak Seong, Chang-Ock Choi*, Su-Gun Lim
Gyeongsang National University, *Korea institute of Science and Technology Information
There is thixo-extrusion to form high strength aluminum alloy. But, it is a problem that grains become grain coarsening during reheating process because the alloy was exposed at high temperature. In order to solve grain growth during reheating process, calcium was added in Al-Zn-Mg alloys. Primary a grain sizes of semi-solid Al- Zn-Mg-(0, 0.4, 0.6 and 0.9, wt.%)Ca were measured with image analyzer after reheating. Measured primary a grain sizes were applied to LSW(Lifshitz-Slyozov and Wagner) equation to check the effect of Ca on grain coarsening. Coarsening rate constant K values of semi-solid Al-Zn-Mg-(0, 0.4, 0.6 and 0.9, wt.%)Ca alloys were 371 mm3s−1, 247 mm3s−1, 198 mm3s−1 and 166 mm3s−1, respectively. As increasing calcium content, K value decreased which means grains are refined. Also, grains of calcium addition were more spherical than that of calcium free.
Al-Mg-Zn alloy, Ca addition, Reheating, Thixo-extrusion.
PDF