Abstract

In the present study, the influence of the pin rotating speed on corrosion behavior and mechanical properties of the friction stir welded (FSW) 6063 aluminum alloy joints was investigated. The welding process was performed at rotating speeds of 800, 1000, and 1200 rpm and a constant traverse speed of 50 mm/min. The joints were analyzed via optical microscopy, scanning electron microscopy, and microhardness test. A cyclic polarization test and electrochemical impedance spectroscopy (EIS) were performed so as to study the effect of the pin rotating speed on corrosion behavior of joints in the solution of sodium chloride (3.5%). Microhardness results showed that the maximum amount of hardness is related to the sample with 1000 rpm rotating speed because of optimized input heat, which caused an increase in the grain refinement and dynamic recrystallization. The cyclic polarization test demonstrated that the corrosion rate in the heat affected zone (HAZ) was higher than that of the base and weld metals; this is due to grain coarsening and an increase of secondary phase particles, which causes intensification of galvanic corrosion. It was found that the higher the pin rotating speed, the higher the corrosion rate. The growth of secondary phase particles was identified due to an input heat increase. Also, EIS results indicated that increasing the pin rotating speed at FSW reduces the polarization resistance (R_P) amount at the Nyquist diagram, followed by a decrease of corrosion resistance. A lower amount of R_P and corrosion resistance verified in the HAZ was compared to those of the weld metal.

中文翻译：

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AA6063搅拌摩擦焊接头的电化学和显微组织研究

摘要

在本研究中，研究了销旋转速度对搅拌摩擦焊接（FSW）6063铝合金接头的腐蚀行为和力学性能的影响。焊接过程以800、1000和1200 rpm的转速以及50 mm / min的恒定移动速度进行。通过光学显微镜，扫描电子显微镜和显微硬度测试对接头进行分析。进行了循环极化试验和电化学阻抗谱（EIS），以研究销钉转速对氯化钠溶液（3.5％）中接头腐蚀行为的影响。显微硬度结果表明，由于优化了输入热量，最大硬度量与转速为1000 rpm的样品有关。这导致晶粒细化和动态再结晶的增加。循环极化试验表明，热影响区（HAZ）的腐蚀速率高于母材和焊缝金属。这是由于晶粒粗化和次级相颗粒的增加，导致电偶腐蚀加剧。已经发现，销旋转速度越高，腐蚀速率越高。由于输入热量增加，确定了次级相颗粒的生长。同样，EIS结果表明，提高FSW引脚的旋转速度会降低极化电阻（这是由于晶粒粗化和次级相颗粒的增加，导致电偶腐蚀加剧。发现销旋转速度越高，腐蚀速率越高。由于输入热量增加，确定了次级相颗粒的生长。此外，EIS结果表明，提高FSW引脚的旋转速度会降低极化电阻（这是由于晶粒粗化和次级相颗粒的增加，导致电偶腐蚀加剧。发现销旋转速度越高，腐蚀速率越高。由于输入热量增加，确定了次级相颗粒的生长。此外，EIS结果表明，提高FSW引脚的旋转速度会降低极化电阻（奈奎斯特图上的R _P）量，随后耐蚀性降低。与焊接金属相比，在热影响区中验证了较低的R _P和耐腐蚀性。