The bucket tooth is one of an excavator components made of manganese steel used to dig and load land into a truck or elsewhere. The impact of the bucket tooth product needs to be increased so that it has longer lifetime. The objective of this research is to know the right composition of manganese in order to obtain the optimal impact strength. Varying the composition of manganese from 11,2% to 15,1% wt Mn are carried out in an induction furnace. Mechanical tests carried out include microstructure observation, impact and hardness testing. The structure of austenite dominates manganese steel with an average grain size of 60 μm (11,2% Mn) and increases up to 45% for the contents of 15,1% Mn. The lowest impact strength (0,08 J/mm2) in specimens with 11,2% Mn, increases up to 42% (0,142 J/mm2) in specimens with 15,1% Mn. The increase of impact strength is affected by grain size and austenite stability. The hardness of manganese steel with 11,2% Mn (330 VHN) increases up to 376 VHN with 15,1% Mn.

ABSTRAK. Penelitian ini bertujuan untuk mengetahui beberapa hal yaitu 1) Metode latihan piramida meningkatkan kekuatan otot tungkai tim putera hoki Universitas Negeri Jakarta. 2) metode latihan multiple set meningkatkan kekuatan otot tungkai tim putera hoki Universitas Negeri Jakarta. 3) Efektivitas metode latihan piramida lebih efektif dibanding dengan metode latihan multiple set terhadap peningkatan kekuatan otot tungkai pada tim putera hoki Universitas Negeri Jakarta. Proses penelitian sampai tahap akhir yaitu pengolahan data, dilakukan mulai dari bulan Januari sampai bulan Juni 2016 di kampus b Universitas Negeri Jakarta.Menggunakan metode eksperimen, dengan jumlah pertemuan sebanyak 16 kali pertemuan. Populasi dan sampel yang diteliti ialah 30 orang atlet putera hoki Universitas Negeri Jakarta, penelitian ini menerapkan latihan single leg press menggunakan dua metode piramida dan metode multiple set.Berdasarkan hasil penelitian, 1) perbandingan data awal dan akhir pada metode latihan piramida, nilai standar deviasi dari difference 26,71, nilai standar error dari mean of difference 7,14, kemudian diperoleh nilai (thitung) 15,35 dan (t tabel) sebesar 2,14. Berarti terjadi peningkatan yang signifikan hasil metode piramida terhadap kekuatan otot tungkai tim putera hoki UNJ. 2) perbandingan data awal dan akhir pada metode latihan multiple set, nilai standar deviasi dari difference 17,76 , nilai standar error dari meanof difference 5,65, kemudian diperoleh nilai (t hitung) 15,84 dan (t tabel) sebesar 2,14. Berarti terjadi peningkatan yang signifikan hasil latihan single leg press menggunakan metode multiple set terhadap kekuatan otot tungkai tim putera hoki UNJ. 3) perbandingan data tes akhir antara metode metode piramida dan multiple set terhadap peningkatan kekuatan otot tungkai tim putera hoki UNJ, rata-rata variabel x (piramida) sebesar 506,73 standar deviasi 38,57 dan varian 1487,92. Rata-rata variabel y (multiple set) sebesar 481,46, standar deviasi 44,80 dan varian 2007,71. kemudian diperoleh nilai t-hitung 1,6. Sedangkan nilai t-tabel sebesar 2,05. Jadi t-hitung t-tabel. Sehingga dapat disimpulkan, metode piramida lebih efektif dibanding metode multiple set terhadap peningkatan kekuatan otot tungkai tim putera hoki Universitas Negeri Jakarta, hanya saja perbedaan hasil peningkatan kekuatan otot tungkai pada kedua metode tidak signifikan.

Parallel, lap, corner, and T joints are commonly used in fusion welding and solid welding. Other joints made are lap and butt joint. This study aims to evaluate a new design of fitting model single U and double U for friction stirr welding of Aluminum. Aluminum sheet 6061with a thickness of 10 mm, will be cut to a length of 150 mm and a width of 100 mm, then a locking groove will be made with an inner size of 5 mm and a length of 150 mm The flow is used to be paired in the FSW process. This experiment results show the high tensile strength that occurs in the double joint u, is 13.4 kN while the average is 12 kN. Single connection experiment u the highest tensile strength is 12.89 kN, while the average value is 10.37 kN. The hardness is higher in double u joints compared to single u joints.

Bimetal is a combination of two dissimilar metals that form a metallurgical bond. The manufacture of bimetallic bushing by centrifugal casting has not been widely developed. There is still no recommendation for optimum temperature used in the manufacture. The aim of this research was to determine the first frozen layer temperature of the aluminum when bronze was poured to produce a well-integrated bond interface. The materials used were aluminum and bronze. Molten metal was pouring into the mold alternately. First, aluminum was poured into the mold. Then, bronze was poured gradually to form a bushing aluminum-bronze bimetallic. The temperature variations of the first frozen layer of aluminum were 27º C, 350º C, 400º C, and 450º C when bronze poured. The molten metal was poured with the filling speed of about 0.2 kg/s into a rotating sand mold. The rotational speed of the mold was 350 rpm. The result shows that the bond interface’s width increases as the first frozen layer aluminum temperature increases. As a result, interface wear and hardness are increased compared to the base metal. Hence, centrifugal casting with the first frozen layer aluminum was 450ºC recommended for aluminum-bronze bimetal bushing applications.