The aim of the present study is to investigate the dependence of the tensile properties of A356 aluminum alloy with respect to the sonication time and holding time after sonication treatment, in terms of the quality index of the tensile properties on the variation in microporosity. The test specimens were fabricated through ultra-high density sonication treatment of Ti-horn, and the tensile properties of sonication-treated alloys were evaluated, together with the variation in the hydrogen concentration, microstructural features, and microporosity with sonication condition. The hydrogen concentration in a melt was practically reduced by degassing action with an increase in sonication time, even though the effectiveness of grain refinement was valid only around an optimal sonication of approximately 5 min and gradually deteriorated beyond this optimal sonication treatment. The grain refinement and degassing action at an optimal sonication treatment practically improved the tensile properties, even at T6-treated condition. Additionally, the nominal level of hydrogen concentration was maintained up to a holding time of approximately 15 min after optimal sonication, and then gradually increased with loss of grain refinement to the level of the no sonication condition. However, any sonication condition could not surpass the effectiveness of T6-treatment on the improvement of tensile properties, even though the overall level of tensile properties could be practically improved through an optimal sonication treatment. The overall level of quality index is practically determined by the strength coefficient and strain-hardening exponent, and the distribution aspect of the quality index with microporosity variation is restricted in a flow curve by the strain-hardening exponent.

本研究的目的是根据拉伸性能的质量指数对微孔率变化的影响，研究 A356 铝合金的拉伸性能与超声处理时间和保持时间的关系。试样通过 Ti-horn 的超高密度超声处理制成，并评估了超声处理合金的拉伸性能，以及氢浓度、显微结构特征和微孔率随超声处理条件的变化。随着超声处理时间的增加，通过脱气作用实际上降低了熔体中的氢浓度，即使晶粒细化的有效性仅在大约 5 分钟的最佳超声处理时有效，并且在超过该最佳超声处理后逐渐恶化。即使在 T6 处理的条件下，最佳超声处理下的晶粒细化和脱气作用实际上也改善了拉伸性能。此外，氢浓度的标称水平在最佳超声处理后保持约 15 分钟的保持时间，然后随着晶粒细化的损失逐渐增加到无超声处理条件的水平。然而，任何超声处理条件都不能超过 T6 处理在提高拉伸性能方面的有效性，即使通过最佳超声处理实际上可以提高拉伸性能的整体水平。