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    固溶工艺对7075铝合金薄板组织与损伤容限性能的影响

    Effect of Solution Process on Microstructure and Damage Tolerance Properties of 7075 Aluminum Alloy Sheet

    • 摘要: 在热空气循环炉中将退火态和加工硬化态7075铝合金薄板加热(升温速率约5 ℃·min−1)至不同温度(466,479 ℃)保温不同时间(5,55 min)进行固溶处理,在气垫炉中将加工硬化态7075铝合金薄板加热(升温速率151~227 ℃·min−1)至479 ℃保温2~3 min进行固溶处理,对固溶处理后的铝合金薄板进行121 ℃保温24 h时效处理,研究了固溶工艺对铝合金薄板组织与损伤容限性能的影响。结果表明:在热空气循环炉中延长保温时间或提高固溶温度时,退火态薄板中的第二相颗粒聚集现象改善,断裂韧度提高,加工硬化态薄板中的第二相颗粒尺寸仍偏小且分布均匀,断裂韧度未发生明显改变。采用气垫炉时由于升温速率高、保温时间较短,加工硬化态薄板中的大尺寸第二相未能充分回溶且呈不规则形貌,断裂韧度相比采用热空气循环炉时下降。孤立或聚集的大尺寸第二相是影响损伤容限性能的关键因素。

       

      Abstract: Annealed and work-hardened 7075 aluminum alloy sheets were soluted at different temperatures (466, 479 ℃) for different times (5, 55 min) in a hot air circulation furnace (heating rate of 5 ℃ · min−1). The work-hardened 7075 aluminum alloy sheet was soluted at 479 ℃ for 2–3 min in a hot air circulation furnace (heating rate of 151–227 ℃ · min−1). The sheets after solution treatment were aged at 121 ℃ for 24 h. The effect of solution treatment process on the microstructure and damage tolerance properties of aluminum alloy sheet was studied. The results show that when the holding time was prolonged or the solution temperature was increased in the hot air circulation furnace, the aggregation behavior of the second phase particles in the annealed sheet was improved, and the fracture toughness was improved; the second phase particles in the work-hardened sheet were small in size and evenly distributed, and the fracture toughness did not change significantly. Due to the high heating rate and short holding time in the air cushion furnace, the large-sized second phases in the work-hardened sheet could not be fully redissolved and showed irregular morphology, and the fracture toughness decreased compared with that in the hot air circulation furnace. Isolated or aggregated large-sized second phases were the key factors affecting the damage tolerance properties.

       

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