7175Al 단조재의 강도와 인성에 대한 불순물과 제조공정의 효과

Abstract

The effects of impurity content and of fabrication processes on the tensile properties and toughness of 7175 Al forgings have been studied using conventionally processed 7075 and 7175 Al forgings and a specially processed 7175 Al forging. A specially processed 7175 Al forging was superior to a conventional 7075 Al forging in both the strength and toughness. These beneficial effects primarily arise from two effects, i.e., the effect of reduction of impurity level and that of application of special fabrication procedures. The reduction of impurity level of Fe and Si has significantly diminished the number of constituent particles containing Cu and Mg. A further reduction of the number of constituent particles has been observed on applying specially designed fabrication process. The reduction of impurity level exerts no significant effect on the dispersion of Cr and Mg containing E phase. However, the application of special fabrication processes results in a coarsening of E phase. This is believed to have an effect to promote a finer grain structure, which may also contribute to the enhancement of strength and touhgness of the alloy.