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为确定晶粒直径与力学性能之间的量化关系,用摩擦搅拌焊(Friction stir welding,FSW)将1.1mm厚的铝合金AA5182-O制作成拼焊板。利用单向拉伸试验获得焊缝和母材的屈服强度;利用显微硬度试验获得横截面显微硬度分布;利用金相分析获得平均晶粒直径。基于经典的晶粒直径与力学性能关系,确定了Hall-Petch方程待定参数。结果发现,焊缝的屈服强度和显微硬度均高于母材;焊缝的平均晶粒直径显著小于母材,分别为5μm和80μm。母材和焊缝的Hall-Petch常数分别为120MPa/107.33MPa·μm1/2和55.33MPa/68.57MPa·μm~(1/2)。
To determine the relationship between grain size and mechanical properties, a 1.1mm thick aluminum alloy AA5182-O was made into a tailor welded plate by Friction stir welding (FSW). The yield strength of the weld and the base metal is obtained by a one-way tensile test; the cross-section microhardness distribution is obtained by the microhardness test; and the average grain diameter is obtained by the metallographic analysis. Based on the relationship between the classical grain diameter and mechanical properties, the Hall-Petch equation to be determined is determined. The results show that the yield strength and microhardness of the weld are higher than the base metal; the average grain size of the weld is significantly smaller than the base metal, respectively 5μm and 80μm. The Hall-Petch constants of the base metal and the weld are respectively 120MPa / 107.33MPa · μm1 / 2 and 55.33MPa / 68.57MPa · μm ~ (1/2).