| Title |
Strengthening Phenomena in Al - Zn - Mg Alloy through Final Thermomechanical Treatment |
| Authors |
우기도(Kee Do Woo); 이기대(Kee Dae Lee); 조현기(Hyun Kee Cho) |
| Abstract |
An investigation has been carried out to clarify the effects of final thermomechanical treatments(FTMT) on strengthening phenomena in comparison with isothermal and two-step ageing in Al-6.94%Zn-2.69%Mg alloy. Al-6.94%Zn-2.69%Mg alloy processed by FTMT exhibits higher strength than that of conventionally processed. From these results, the super-hardening effects obtained by final thermomechanical treatment may be explained by the interactions between dislocations induced by deformation and precipitates formed by ageing. Deformation less than 30% and final ageing at lower temperature than the solvus temperature of G.P.zones are desirable in obtaining remarkable improvement in mechanical properties by FTMT. The mechanical properties of Al-6.94%Zn-2.69%Mg alloy processed by FTMT exhibit lower strength than those of isothermal and two-step ageing when the temperature of final ageing is higher than the solvus temperature of G.P.zones. Maximum value of 0.2% proof stress resulted by FTMT is 57㎏/㎟, while that resulted by isothermal ageing is 41㎏/㎟. |