摘要
搅拌摩擦焊(FSW)的余热溶解析出相降低了沉淀强化AA2014合金的接头质量。本研究采用最小量润滑(MQL)技术来散热,将采用两步法制备的石墨烯纳米流体作为冷却剂,用光学显微镜、扫描电镜、透射电镜、X射线衍射和差示扫描量热法研究晶粒结构和析出相的发展。结果表明,在不同转速和焊接速度组合下,不同的热循环对析出相的转变不同,从而对焊缝性能产生调节作用,成功消除无沉淀析出带的形成。采用n-MQL技术产生了稳定的θ相,从而使焊接接头有更高的焊接性能。在1200 r/min的转速和72 mm/min的焊接速度下,建立了具有优异性能的工艺窗口。
Dissolution of precipitates by excess heat from friction stir welding(FSW)diminishes the joint quality of precipitation strengthened AA2014 alloy.Minimum quantity lubrication(MQL)technique is employed in this study to dissipate the unwanted heat.Graphene nanofluid prepared using two-step method with graphene nanoplatelets in water is used as the coolant.The development of grain structure and precipitation is studied using optical microscopy,scanning electron microscopy,transmission electron microscopy,X-ray diffraction and differential scanning calorimetry.The results show that the distinct thermal cycles occurring at each combination of rotational speed and welding speed transform the precipitates differently,thereby regulating the weld properties.The formation of precipitate free zones has been successfully eliminated.n-MQL has been observed to develop stableθprecipitates that produce higher weld properties.The process window for superior properties is established at the rotational speed of 1200 r/min and welding speed of 72 mm/min.
基金
Project(19242197218/2020/AR1) supported by Anna Centenary Research Fellowship provided by the Center for Research, Anna University, Chennai, Tamilnadu, India。
