摘要
增材搅拌摩擦沉积(additive friction stir deposition,AFSD)具有沉积温度低、增材质量好、制造效率高等特点,在航空航天制造领域具有广阔的应用前景。本文详细介绍了AFSD技术,深入剖析了AFSD对三类析出强化型铝合金组织和性能的影响规律及机理,并指出了制约高强铝合金构件AFSD制造的关键问题。AFSD在固相下进行沉积,克服了基于激光和电弧沉积的气孔和热裂纹缺陷。然而,在AFSD过程中,由于沉积金属的冷却速度较慢,敏感温度区间的停留时间较长,在增材时后续沉积层对前一层,甚至前几层均有热作用。因此,沉积样品中部与底部的晶内强化相粗大,使得沉积层中下部的强度急剧下降。沉积层顶部不受二次或多次热循环的影响,析出相分布均匀,力学性能较好,但仍低于基体材料。时效处理可使AFSD过程固溶的部分元素再次析出,性能轻微提升,但始终无法达到固溶+时效(T6)的水平。虽然沉积态经过T6处理后可再次形成均匀细小的强化相,使其强度重新达到峰值,但在固溶的同时,沉积材料将发生晶粒的异常长大(abnormal grain growth,AGG)问题,因此,通常不建议对AFSD沉积金属进行固溶处理。为了实现高强度析出强化铝合金构件的AFSD制造,未来还需要在合金化设计、复合强化、工艺创新等方面开展进一步的研究工作。
Additive friction stir deposition(AFSD)is a technology with several advantages for aerospace manufacturing.It is particularly valuable because it can deposit materials at low temperatures while retaining high quality and efficiency.This article introduces the operations of AFSD in detail and investigates its effect on three types of precipitation-reinforced aluminum alloys.Key challenges hindering the production of high-strength aluminum alloy components through AFSD are highlighted.AFSD utilizes solid-phase deposition to avoid problems like porosity and thermal cracking that can occur with other types of deposition,such as laser and arc depositions.However,the slow cooling of the deposited metal and the long residence time in the sensitive temperature range can cause issues.Subsequent layers exert a thermal effect on the previous layers during the AFSD process.This can lead to coarsening of the precipitates in the middle and lower regions,resulting in decreased strength in these areas.The top layer remains unaffected,but has poorer mechanical properties compared to the base material.To improve performance,aging treatment can be used to cause reprecipitation of some elements dissolved during AFSD,but it does not reach the values achieved by solid solution and aging(T6)treatment.T6 treatment after AFSD can renew uniformly distributed fine-strengthening precipitates,but it triggers abnormal grain growth(AGG)in the deposited material.Therefore,it is generally not recommended to subject solution treatment to metals deposited with AFSD.Further research should focus on alloy design,composite reinforcement and innovative techniques,which are essential to obtain high-strength precipitation-reinforced aluminum alloy components through AFSD.
作者
吴永泰
杜成超
任旭东
WU Yongtai;DU Chengchao;REN Xudong(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu,China;School of Mechanical Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu,China)
出处
《材料工程》
北大核心
2025年第12期109-121,共13页
Journal of Materials Engineering
基金
国家自然科学基金项目(U21A20138,52205369)
江苏省自然科学基金(BK20210756)
江苏省博士后基金(2021K035A)。
关键词
固相增材制造
铝合金
搅拌摩擦增材
增材搅拌摩擦沉积
析出相
solid-state additive manufacturing
aluminium alloy
friction stir additive
AFSD
precipitated phase
