(重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶400030)
摘 要: 采用硬度和單軸拉伸測試，結(jié)合差示掃描量熱法(DSC)，分析預(yù)時效、預(yù)應(yīng)變和預(yù)應(yīng)變后預(yù)時效3種預(yù)處理工藝對Al-Mg-Si合金自然時效的抑制及烘烤硬化性能的影響。結(jié)果表明：預(yù)時效能有效抑制合金的自然時效，提高烘烤硬化效果(BHR)，但預(yù)時效時間為10 min時，烘烤前強度較高，并且烘烤后塑性降低；預(yù)時效前加入預(yù)應(yīng)變不僅能進一步抑制合金的自然時效，且在烘烤強度明顯增加的同時保持合金伸長率較高，其中合金經(jīng)5%預(yù)應(yīng)變及5 min預(yù)時效的烘烤硬化性能最好。預(yù)處理后合金的DSC曲線中原子團簇的溶解峰消失，且β″相析出峰提前，說明預(yù)處理可抑制合金在自然時效過程中原子團簇的形成，加速烘烤過程中β″強化相的析出從而抑制自然時效，增加烘烤效果。
關(guān)鍵字: 鋁合金；預(yù)應(yīng)變；預(yù)時效；自然時效；烘烤硬化
（College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China）
Abstract:The effects of pre-ageing, pre-straining and pre-straining in combination with pre-ageing on the suppressing of natural ageing and bake hardening response (BHR) of Al-Mg-Si alloys were investigated by means of hardness, tensile test and differential scanning calorimetry (DSC) analysis. The results show that pre-ageing can suppress natural ageing of the alloy and improve its BHR effectively. When pre-ageing time is 10 min, the strength of the alloy before baking is too high and the plasticity after baking decreases. Adding pre-straining before pre-ageing can suppress natural ageing further and retain the good elongation, while improves BHR obviously. The alloy after 5% pre-straining and 5 min pre-ageing sample has the best BHR. In DCS curves, the dissolution peak of clusters disappear, β″ precipitation peak shifts to lower temperature in pre-treated samples. It indicates that the pre-treatments suppress the formation of clusters during natural ageing of the alloy, and accelerate the precipitation of β″ phase during baking, with the results of natural ageing suppressed and BHR enhanced.
Key words: aluminum alloy; pre-straining; pre-ageing; natural ageing; bake hardening response
