Baja berkekuatan tinggi sebagai material yang umum digunakan pada kendaraan tempur memiliki densitas yang besar sehingga membatasi mobilitas kendaraan. Untuk meningkatkan mobilitas kendaraan tempur, dilakukan pengembangan material dengan densitas lebih kecil, seperti komposit bermatriks aluminium. Al 2024 adalah salah satu paduan yang dapat dilaku panas untuk menaikkan kekuatannya. Penambahan partikel keramik seperti SiC pun dapat menaikkan kekuatan dan kekerasan matriks, sifat yang dibutuhkan untuk menahan penetrasi balistik. Oleh karena itu, penelitian ini dilakukan untuk mengetahui pengaruh kadar SiC dan laku panas terhadap ketahanan balistik pelat komposit.
Partikel penguat nano SiC sebanyak 0.1, 0.2, dan 0.3 wt% ditambahkan ke dalam matriks Al 2024. Komposit difabrikasi menggunakan metode pengecoran tekan sebelum dilaku panas dengan solution treatment pada 495oC selama 2 jam, didinginkan cepat dengan air, serta dilakukan penuaan pada temperatur 190oC selama 1 jam. Pelat komposit kemudian diuji balistik dengan peluru 9 mm dan MU5-TJ yang setara dengan uji balistik NIJ Tipe II dan Tipe III. Karakterisasi lain seperti pengamatan metalografi, pengujian kekerasan, tarik, dan impak dianalisis berdasarkan data sekunder dari berbagai peneliti.
Hasil pengujian menunjukkan semua sampel tahan terhadap uji balistik NIJ Tipe II, namun semua tidak dengan uji balistik NIJ Tipe III. Penambahan kadar penguat nano SiC pada matriks menaikkan kekerasan, sedangkan elongasi dan nilai impak menurun. Hal ini dikarenakan mekanisme penguatan oleh partikel penguat, seperti transfer beban, penguatan orowan, ketidaksesuaian CTE, serta penghalusan butir. Perlakuan panas menaikkan kekerasan dan kekuatan tarik secara signifikan walaupun menurunkan kekuatan impak, karena partikel penguat bertindak sebagai situs nukleasi heterogen pada pembentukan presipitat penguat pada proses laku panas.
High strength steel as a common material for combat vehicle have high density that will restrict the vehicles mobility. To enhance its mobility, materials with lower density are being developed, one of it is aluminium matrix composite. Al 2024 is an alloy that can be heat treated to increase its strength. The addition of ceramic particles like SiC can also increase the strength and hardness of the alloy. For that, this research is intended to understand the effect of heat treatment and nano SiC content inside Al 2024 matrix on its balistic properties.
Nano SiC reinforcement particles is added to Al 2024 matrix with content variation of 0.1, 0.2, and 0.3 wt%. The composite plates were fabricated by squeeze casting before heat treated with solution treatment at 495oC for 2 hours, water quench, and aging at 190oC for 1 hour. The samples then subjected for balistic impact of 9 mm and MU5-TJ projectile, which equal to Type II and Type III NIJ standard. Other characterization such as microstructure observation, hardness, tensile, and impact testing is analyzed by secondary data from various research.
Testing results showed that all composite plate can endure Type II ballistic testing, but not Type III test. The addition of nano SiC content inside the matrix increases its hardness, but lower the elongation and impact endurance. This is due to the strengthening mechanisms by reinforcement, such as load transfer, orowan strengthening, CTE mismatch strengthening, and grain boundary strengthening. Even so, there are no significant effect to its tensile strength. Heat treatment increases hardness and tensile strength significantly, but lower its impact properties. Reinforcement particles act as heterogen nucleation sites for precipitate to form in heat treatment process.
Komposit dibuat dengan metode squeeze casting yang diikuti dengan perlakuan panas T6 pada temperatur 470°C selama dua jam, pendinginan cepat dengan air, dan penuaan buatan pada temperatur 145°C, 175°C, dan 205°C selama kurang lebih satu jam. Penguatan partikel nano ditambahkan ke dalam lelehan paduan aluminium selama proses fabrikasi dengan kadar 0,3 % berat. Selanjutnya, pelat komposit diuji dengan pengujian karakterisasi berupa pengamatan struktur mikro menggunakan mikroskop optik dan SEM-EDS, serta pengujian mekanik seperti uji kekerasan, uji tarik, dan uji impak.
Hasil karakterisasi menunjukkan bahwa perlakuan panas dan penuaan buatan T6 mempengaruhi konstituen dan fasa struktur mikro. Hasil penelitian juga menunjukkan bahwa perlakuan panas dan penuaan buatan T6 secara signifikan meningkatkan kekerasan dan kekuatan tarik, tetapi tidak secara signifikan meningkatkan ketangguhan impak, yang secara langsung berkaitan dengan perubahan mikrostruktur yang terjadi selama proses penuaan. ......Al 2024 alloy is known as an alloy that has high strength and is capable of being heat treated. Its low density along with good mechanical properties make Al 2024 alloy widely used in the automotive field. On this basis, Al 2024 alloy was studied to determine its usefulness in the automotive industry. The addition of reinforcing particles in the form of Al2O3 ceramics is to improve the mechanical properties of the material such as hardness, tensile strength and impact toughness which are related to the protective ability of the material. This study was conducted to determine the effect of heat treatment in the form of T6 artificial ageing temperature variations on the mechanical properties and microstructure result of Al 2024/Al2O3 nano particle composites.
The composites were fabricated by the squeeze casting method followed by T6 heat treatment at 470 °C for two hours, rapid cooling with water, and artificial ageing at 145°C, 175 °C, and 205 °C for approximately one hour. Nano-particle reinforcement was added to the aluminum alloy melt during the fabrication process at 0.3 wt%. Furthermore, the composite plates were tested by characterization testing in the form of microstructure observation using optical microscope and SEM-EDS, and mechanical testing such as hardness test, tensile test, and impact test.
The characterization show that heat treatment and T6 artificial ageing affected the constituent and phase of the microstructure. The results also show that heat treatment and T6 artificial ageing significantly increase the hardness and tensile strength, but doesn’t significantly increase impact toughness, which directly related to the microstructural changes that occur during the ageing process.
