PENGARUH PROSES QUENCHING TERHADAP SIFAT FISIK DAN MEKANIK SAMBUNGAN LAS AA 2024

PENGARUH PROSES QUENCHING TERHADAP SIFAT FISIK DAN MEKANIK SAMBUNGAN LAS AA 2024
Gilang Cahyo Septian
Program Studi Teknik Mesin, Universitas Muhammadiyah Ponorogo e-mail : cgilang921@gmail.com
ABSTRACT
This study aims to analyze the effect of variations in cooling media on the quality of AA 2024 aluminum alloy welded joints produced using the MIG welding process, in terms of macrostructure, microstructure, and mechanical properties. The welding process was carried out using the MIG (Metal Inert Gas) method with ER 5356 filler metal and argon shielding gas in the 1G position. After welding, the specimens were cooled through a quenching process using air, propylene glycol, and saltwater as cooling media. The tests conducted included a weld bead test, macrostructural and microstructural observations, and tensile testing. The results showed that variations in cooling media affected the quality of AA 2024 aluminum alloy welded joints. Propylene glycol produced the best joint quality, with the lowest amount of porosity, a more homogeneous microstructure, the highest tensile strength of 207.11 MPa, and a strain of 2.41%. Air cooling produced a coarser microstructure and more porosity due to its slower cooling rate. Meanwhile, saltwater cooling produced the finest microstructure and the highest elastic modulus of 9159.12 MPa, but had the lowest tensile strength of 121.65 MPa due to the formation of porosity, microcracks, and high residual stresses. Based on the results, propylene glycol was found to be the most optimal cooling medium because it provided the best balance between tensile strength, ductility, and material stiffness.
Keywords: AA 2024, Cooling Media Variation, MIG Welding, Weld Bead Test, Macrostructure and Microstructure, Tensile Test.