Khan Shaheer Ahmed, Sohail Muhammad
Department of Materials Engineering, NED University of Engineering and Technology, Karachi, Pakistan.
PLoS One. 2025 May 8;20(5):e0322456. doi: 10.1371/journal.pone.0322456. eCollection 2025.
The utilization of thermoplastics is extensively prevalent in modern industrial sectors owing to their distinctive mechanical features. Friction stir welding is recognized as a distinctive joining technology that addresses the weaknesses of heat-induced fusion welding. This friction-stirred solid-state welding technology can be effectively employed to join various difficult-to-weld polymeric materials. This paper examines the weldability of friction stir butt welding utilizing a cylindrical tapered threaded tool on a 3 mm thick Acrylonitrile Butadiene Styrene (ABS) and Polycarbonate (PC) polymers. The impact of tool rotational speed (800 and 1200 rpm) and tool traverse speed (10 mm/min to 50 mm/min) on the joint strength of welded samples has been analyzed. The maximum joint efficiency achieved is 52.71% for ABS while using a rotational speed of 1200 RPM and a traverse speed of 10 mm/min. For PC, the maximum joint efficiency is 54% with a rotational speed of 800 RPM and a traverse speed of 40 mm/min. The joint efficiency of polymer is significantly improved as a result of the effective heat distribution and fusion during the welding. The tensile strength of ABS polymer decreases as the traverse speed increases from 10 mm/min to 50 mm/min at both rotational speeds of 800 and 1200 rpm. However, the tensile strength of PC polymer exhibits fluctuations as the traverse speed increases from 10 mm/min to 50 mm/min. This behavior may be attributed to the fluctuating heating and cooling conditions that occur during the welding process at varying rotation and traverse speeds. In contrast to the polymeric base material, the weld zone demonstrated a lower hardness value. The heated tool induces material softening, which results in a reduction in hardness. An examination of alterations in the microstructure of the weld zone was conducted using scanning electron microscopy and stereo microscopy. The observed microstructures were applied to determine the reasons for the decrease in strength. The micrographs illustrate the formation of a fragmentation, attributable to the residual stress generated during the rapid cooling of the liquid polymer. Moreover, a highly increased temperature or traverse speed may result in the formation of voids at the joint interface.
由于其独特的机械特性，热塑性塑料在现代工业领域的应用极为广泛。搅拌摩擦焊被认为是一种独特的连接技术，可解决热致熔焊的缺点。这种搅拌摩擦固态焊接技术可有效地用于连接各种难焊的聚合物材料。本文研究了使用圆柱形锥形螺纹工具对3毫米厚的丙烯腈-丁二烯-苯乙烯（ABS）和聚碳酸酯（PC）聚合物进行搅拌摩擦对接焊的可焊性。分析了工具转速（800和1200转/分钟）和工具横向速度（10毫米/分钟至50毫米/分钟）对焊接样品接头强度的影响。对于ABS，在转速为1200转/分钟和横向速度为10毫米/分钟时，实现的最大接头效率为52.71%。对于PC，在转速为800转/分钟和横向速度为40毫米/分钟时，最大接头效率为54%。由于焊接过程中有效的热分布和熔合，聚合物的接头效率得到显著提高。在800和1200转/分钟的两种转速下，随着横向速度从10毫米/分钟增加到50毫米/分钟，ABS聚合物的拉伸强度降低。然而，随着横向速度从1毫米/分钟增加到50毫米/分钟，PC聚合物的拉伸强度呈现波动。这种行为可能归因于在不同的旋转和横向速度下焊接过程中发生的加热和冷却条件的波动。与聚合物基材相比，焊接区显示出较低的硬度值。加热的工具会导致材料软化，从而导致硬度降低。使用扫描电子显微镜和立体显微镜对焊接区的微观结构变化进行了检查。观察到的微观结构用于确定强度降低的原因。显微照片显示了碎片的形成，这归因于液态聚合物快速冷却过程中产生的残余应力。此外，过高的温度或横向速度可能导致接头界面处形成空隙。
