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<p>This study investigates the relationship between heat input and the mechanical performance of friction stir-welded joints of AA7075 with different tool rotational speeds. The Linear Energy Index (LEI) changed significantly between low welding speeds at 600&#xa0;rpm and high welding speeds at 1800&#xa0;rpm, despite the constant travel speed of 50&#xa0;mm/min, resulting in different levels of heat generation. Tensile testing showed that joints produced under moderate heat input, particularly at 1200&#xa0;rpm with an LEI of 24 and at 1500&#xa0;rpm with an LEI of 30, exhibited superior mechanical properties. At 1500&#xa0;rpm, the joint achieved an ultimate tensile strength of 231.6&#xa0;MPa with an elongation of 15.55%, significantly higher than the 143.8&#xa0;MPa strength and 6.29% elongation recorded at 600&#xa0;rpm. Microstructural observations revealed fine equiaxed grains of approximately 6&#xa0;μm within the stir zone, along with uniformly distributed dimples on the fracture surface, confirming ductile failure. EBSD results showed a larger fraction of high-angle grain boundaries (HAGBs), ranging between 76% and 79%, and an average misorientation of 30 ° to 33°, indicating extensive dynamic recrystallization. Microhardness measurements followed a characteristic valley-shaped pattern, with the stir zone displaying the highest hardness of nearly 80 HV.</p>

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Effects of Heat Supplied on Metallurgical and Mechanical Properties in Friction Stir Welding of Aerospace Grade Non-Heat-Treated AA7075

  • 期刊论文

  • 发表日期：

    2026年2月20日

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  • Gyander Ghangas,
  • Vikas Goyat,
  • Sunil Kadiyan,
  • Santosh Kumar Rai,
  • Mahesh Kumar Gupta,
  • Husain Mehdi

摘要

This study investigates the relationship between heat input and the mechanical performance of friction stir-welded joints of AA7075 with different tool rotational speeds. The Linear Energy Index (LEI) changed significantly between low welding speeds at 600 rpm and high welding speeds at 1800 rpm, despite the constant travel speed of 50 mm/min, resulting in different levels of heat generation. Tensile testing showed that joints produced under moderate heat input, particularly at 1200 rpm with an LEI of 24 and at 1500 rpm with an LEI of 30, exhibited superior mechanical properties. At 1500 rpm, the joint achieved an ultimate tensile strength of 231.6 MPa with an elongation of 15.55%, significantly higher than the 143.8 MPa strength and 6.29% elongation recorded at 600 rpm. Microstructural observations revealed fine equiaxed grains of approximately 6 μm within the stir zone, along with uniformly distributed dimples on the fracture surface, confirming ductile failure. EBSD results showed a larger fraction of high-angle grain boundaries (HAGBs), ranging between 76% and 79%, and an average misorientation of 30 ° to 33°, indicating extensive dynamic recrystallization. Microhardness measurements followed a characteristic valley-shaped pattern, with the stir zone displaying the highest hardness of nearly 80 HV.