Influence of tool offset on microstructure and properties of Mg/Al dissimilar alloys by friction stir welding joints at low heat input

• Published in: International journal of advanced manufacturing technology 2020-08, Vol.109 (9-12), p.2845-2853
• Main Authors: Deng, Yongfang, Qiu, Zherui, Zuo, Dunwen, Zeng, Jincheng, Zhang, Weichao
• Format: Article
• Language: English
• Subjects: CAE) and Design; Computer-Aided Engineering (CAD; Dissimilar material joining; Engineering; Eutectic temperature; Friction stir welding; Industrial and Production Engineering; Intermetallic compounds; Macrostructure; Magnesium base alloys; Mechanical Engineering; Mechanical properties; Media Management; Microstructure; Optical microscopes; Original Article; Welded joints
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-020-05788-8

The composition of intermetallic compounds and mechanical properties during friction stir welding of 2024 aluminum and AZ31B magnesium alloys was investigated by using offset tool at low heat input. The macrostructure of the Mg/Al joints was investigated by optical microscope, and microstructure characteristics were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. The fracture section was also observed. It is found that the mechanical strength of the joint slowly decreases as the value of tool offset increases first and then decreases at the Al-side. The result showed that the joints have the best mechanical properties when offset 0.5 mm and the amount of IMCs is low. And it is found that only IMCs Al12Mg17 is found in the joints. Since Al 3 Mg 2 and Al 12 Mg 17 have eutectic temperatures of 450 °C and 437 °C, respectively, the offset caused the temperature to decrease during the FSW process, allowing Al 12 Mg 17 , with a lower eutectic temperature, to form easily.