鋁合金攪拌摩擦焊后人工時效力學性能數值模擬

鋁合金攪拌摩擦焊后人工時效力學性能數值模擬Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

采用KWN模型構建攪拌摩擦焊接中Al-Mg-Si系鋁合金沉淀相演化計算模型，通過將屈服強度分為晶粒大小、固溶相和析出相三部分貢獻，可以計算平板攪拌摩擦焊后的屈服強度和硬度。進一步研究不同焊后人工時效條件下，焊接平板力學性能變化的機理。結果表明：更長的焊后保溫時間有利于攪拌區(qū)力學性能的回復；較高的保溫溫度有利于攪拌區(qū)力學性能的快速回復，但是當溫度高于200℃時，長時間保溫會使母材軟化，不利于力學性能回復；通過焊后人工時效不能明顯改善熱影響區(qū)的力學性能。

KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

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