Hasil Pencarian  ::  Simpan CSV :: Kembali

"ABSTRAKSelongsong merupakan salah satu bagian penting pada munisi tempat dimana bubuk mesiu, primer, dan peluru. Material yang digunakan untuk fabrikasi selongsong adalah paduan Cu-28Zn atau cartridge brass. Selongsong munisi dibuat dengan beberapa proses diantaranya adalah pengecoran, canai, dan penarikan dalam. Sering terjadi retak dan robek pada tahap fabrikasi. Telah dilakukan beberapa penambahan unsur paduan, tetapi hasilnya belum optimal. Dibutuhkan unsur paduan untuk meningkatkan kekuatan paduan cartridge brass tanpa mengorbankan keuletan. Aluminium dipilih sebagai unsur paduan tersebut.Pada penelitian ini, paduan cartridge brass dengan penambahan 1.9, 5.7, dan 6.2 wt. % Al dihasilkan dengan pengecoran gravitasi. Paduan tersebut kemudian dihomogenisasi pada 800 °C selama 2 jam. Karakterisasi material meliputi analisis struktur mikro menggunakan mikroskop optik dan Scanning Electron Microscope (SEM) - Energy Dispersive X-Ray (EDX), serta uji kekerasan Rockwell B, mikro Vickers, dan uji tarik.Hasil pengujian menunjukkan bahwa penambahan Al meningkatkan sifat mekanis paduan Cu-28Zn. Kekerasan, kekuatan tarik, dan tegangan luluh meningkat, sedangkan nilai elongasi menurun seiring penambahan Al. Peningkatan sifat mekanis disebabkan penambahan unsur Al mempromosi fasa beta dan memfasilitasi fasa gama dengan penambahan berlebih. Secara keseluruhan fasa gama yang terbentuk meningkatkan sifat mekanis paduan dengan mekanisme penguatan dispersi.

---

ABSTRACTCartridge case is an important part of bullet where the gun powder, primer, and bullet take place. Common material that is used to make cartridge case is Cu-28Zn alloy or known as cartridge brass. Cartridge case is made by some processes, that include casting, rolling, and deep drawing. Cracking and torning are often found in the fabricating process. Many kind of alloying elements were added in order to minimize those problems, but the results obtained are still unsatisfying. Another alloying element is needed that could improve the cartridge case without sacrificing the ductility. Aluminum is chosen to be thataforementioned alloying element.In this research, cartridge brass alloy with addition of 1.9, 5.7, and 6.2 wt.%Al were fabricated by gravity die casting. To homogenize the composition, the alloy was heated at 800 °C for 2 hours. Material characterizations consisted ofmicrostructural analysis using optical microscope and Scanning Electron Microscope (SEM) - Energy Dispersive X-Ray (EDX), Rockwell B, Microvicker hardness testing, and tensile testing.The result obtained shows that Al addition improved the mechanical properties of Cu-28Zn alloy. Hardness, tensile strength, and yield strength increased, but the elongation decreased due to addition of Al. Increasing of Al composition in Cu-28Zn promotes beta phase and facilitates gamma phase with excessive addition. Overall, the gamma phase enhances the mechanical properties of Cu-28Zn alloy with dispersion strengthening mechanism."

"ABSTRACTSelongsong merupakan salah satu bagian penting pada munisi tempat dimana bubuk mesiu, primer, dan peluru. Material yang digunakan untuk fabrikasi selongsong adalah paduan Cu-28Zn atau cartridge brass. Selongsong munisi dibuat dengan beberapa proses diantaranya adalah pengecoran, canai, dan penarikan dalam. Sering terjadi retak dan robek pada tahap fabrikasi. Telah dilakukan beberapa penambahan unsur paduan, tetapi hasilnya belum optimal. Dibutuhkan unsur paduan untuk meningkatkan kekuatan paduan cartridge brass tanpa mengorbankan keuletan. Aluminium dipilih sebagai unsur paduan tersebut. Pada penelitian ini, paduan cartridge brass dengan penambahan 1.9, 5.7, dan 6.2 wt. Al dihasilkan dengan pengecoran gravitasi. Paduan tersebut kemudian dihomogenisasi pada 800 C selama 2 jam. Karakterisasi material meliputi analisis struktur mikro menggunakan mikroskop optik dan Scanning Electron Microscope SEM - Energy Dispersive X-Ray EDX , serta uji kekerasan Rockwell B, mikro Vickers, dan uji tarik. Hasil pengujian menunjukkan bahwa penambahan Al meningkatkan sifat mekanis paduan Cu-28Zn. Kekerasan, kekuatan tarik, dan tegangan luluh meningkat, sedangkan nilai elongasi menurun seiring penambahan Al. Peningkatan sifat mekanis disebabkan penambahan unsur Al mempromosi fasa beta dan memfasilitasi fasa gama dengan penambahan berlebih. Secara keseluruhan fasa gama yang terbentuk meningkatkan sifat mekanis paduan dengan mekanisme penguatan dispersi.

---

ABSTRACTCartridge case is an important part of bullet where the gun powder, primer, and bullet take place. Common material that is used to make cartridge case is Cu 28Zn alloy or known as cartridge brass. Cartridge case is made by some processes, that include casting, rolling, and deep drawing. Cracking and torning are often found in the fabricating process. Many kind of alloying elements were added in order to minimize those problems, but the results obtained are still unsatisfying. Another alloying element is needed that could improve the cartridge case without sacrificing the ductility. Aluminum is chosen to be thataforementioned alloying element.In this research, cartridge brass alloy with addition of 1.9, 5.7, and 6.2 wt. Al were fabricated by gravity die casting. To homogenize the composition, the alloy was heated at 800 C for 2 hours. Material characterizations consisted ofmicrostructural analysis using optical microscope and Scanning Electron Microscope SEM Energy Dispersive X Ray EDX , Rockwell B, Microvicker hardness testing, and tensile testing.The result obtained shows that Al addition improved the mechanical properties of Cu 28Zn alloy. Hardness, tensile strength, and yield strength increased, but the elongation decreased due to addition of Al. Increasing of Al composition in Cu 28Zn promotes beta phase and facilitates gamma phase with excessive addition. Overall, the gamma phase enhances the mechanical properties of Cu 28Zn alloy with dispersion strengthening mechanism."

"[Selongsong merupakan salah satu bagian penting pada munisi. Material yang biasanya digunakan untuk mebuat munisi adalah cartridge brass. Dalam pembuatan munisi, sering terdapat masalah yaitu retak dan robek saat proses tarik dalam. Untuk mengurangi masalah tersebut, maka pada penelitian ini mangan digunakan sebagai unsur paduan untuk meningkatkan keuletan cartridge brass. Penelitian ini bertujuan untuk memfabrikasi paduan cartridge brass dengan penambahan unsur Mn serta mengamati pengaruh Mn (1.26, 3.23, dan 5.83 % berat) terhadap struktur mikro dan sifat mekanisnya. Karakterisasi material meliputi uji kekerasan, uji tarik, dan pengamatan struktur mikro menggunakan mirkoskop optik dan SEM/EDX. Hasil pengujian menunjukkan bahwa dengan penambahan 1.26 dan 3.23 wt.% Mn, kekerasan, kekuatan tarik dan keuletan paduan meningkat karena adanya penguatan larutan padat oleh Mn pada fasa α Cu. Sedangkan dengan penambahan Mn sebanyak 5.83 wt.%, kekerasan semakin bertambah namun nilai kekuatan tarik hanya meningkat sedikit dan keuletan menurun karena adanya fasa β? yang terbentuk.

---

, One important part of bullet is its shell. Common material that is used to make bullet shell is cartridge brass. In the making process of bullet shell there are some problems that are often found such as cracking and torning. In order to minimize those problems, manganese is used in this research to increase cartridge brass’ ductility. This research is intended to fabricate cartridge brass alloy with addition of Mn and to study effect of Mn (1.26, 3.23, and 5.83 wt. %) on microstructure and mechanical properties. It was characterized by hardness testing, tensile testing, and microstructure analysis using optical microscope and SEM/EDX. The result showed that with the addition of 1.26 and 3.23 wt. % Mn, the tensile strength and ductility of the alloys are increased. This is due to to solid solution strengthening mechanism of Mn in single α Cu phase. In the other hand, with the addition of 5.83 wt.% Mn, the hardness and tensile strength increased and the elongation decreased. The reason is because there are β’ phases that occur in this composition.

]"

"Selongsong peluru adalah salah satu komponen yang terpenting dalam peluru karena merupakan tempat mesiu, proyektil, dan primer. Material yang digunakan untuk membuat selongsong peluru adalah paduan cartridge brass (Cu-Zn) dengan kandungan seng dalam rentang 28 ? 32 wt.%. Selongsong peluru difabrikasi dengan melewati beberapa tahap yaitu pengecoran, canai dingin, deep drawing, dan anil. Persen deformasi yang diberikan saat proses fabrikasi mencapai lebih dari 70 %, maka dari itu agar dapat melalui seluruh proses fabrikasi diatas dibutuhkan paduan kuningan yang memiliki keuletan tinggi dan perilaku rekristalisasi yang dapat dikontrol. Penambahan unsur Mn diharapkan dapat meningkatkan keuletan dari paduan cartridge brass tanpa mengorbankan kekuatan dari paduan tersebut. Pada penelitian ini, paduan Cu-31Zn dengan penambahan 9 wt.% Mn difabrikasi dengan pengecoran gravitasi. Untuk memperoleh paduan dengan komposisi kimia yang homogen maka dilakukan perlakuan panas homogenisasi pada temperatur 800 oC selama 2 jam. Kemudian paduan dilakukan canai dingin dengan deformasi 20, 40, dan 70 %. Selanjutnya paduan dengan deformasi 70 % dilakukan perlakuan panas anil dengan variasi temperatur 300, 400, dan 600 oC selama 30 menit. Karakterisasi material yang dilakukan pada penelitian ini meliputi analisis struktur mikro dengan mikroskop optik dan Scanning Electron Microscope (SEM) ? Energy Dispersive Spectroscopy (EDS), dan pengujian kekerasan microvickers. Hasil penelitian menunjukkan bahwa peningkatan derajat deformasi sebesar 20, 40, dan 70 % menyebabkan pemipihan fasa kedua dengan L/T ratio masing-masing sebesar 4, 11,6, dan 18. Selain itu juga terjadi peningkatan kekerasan paduan yaitu sebesar 68, 147, 171, dan 205 HV. Sementara proses anil dengan variasi temperatur 300, 400, dan 600 oC menyebabkan terjadinya fenomena recovery, rekristalisasi (dgrain ~ 5 μm), dan grain growth (dgrain ~ 40 μm) yang ditandai dengan penurunan kekerasan spesimen yaitu sebesar 201, 128, dan 171 HV. Penambahan Mn menyebabkan pertumbuhan fasa kedua mengandung sedikit Zn dan Mn akibat kecenderungan ordering Cu dan Mn yang meningkatkan nilai kekerasan dan memperlambat laju rekristalisasi, sehingga dibutuhkan temperatur anil dan/atau waktu yang lebih tinggi untuk mencapai rekristalisasi sempurna pada paduan cartridge brass dengan penambahan Mn.

---

Cartridge shell is one of the most important components in a bullet because it contains gunpowder, projectiles, and primer. The material used to make cartridge shells are cartridge brass alloys (Cu-Zn) with the zinc content in the range of 28 ? 32 wt.%. Bullet casings are manufactured by passing through several stages fabrication, which are casting, cold rolling, deep drawing, and annealing. The degree of deformation during the fabrication process reaches 70 % or more. Therefore in order to be able to go through the whole process of fabrication it is required to use brass alloys that have high ductility and recrystallization behavior that can be controlled. The addition of Mn is expected to improve the ductility of the cartridge brass alloy without sacrificing its strength.

In this study, the characteristics of Cu-31Zn alloy with the addition of 9 wt.% Mn fabricated by gravity casting was observed. To obtain alloys with homogeneous chemical composition, homogenizing heat treatment was carried out with the temperature of 800 °C for 2 hours. Then the alloys were cold rolled with degree of deformation of 20, 40, and 70 %. Furthermore, the specimens with 70 % degree of deformation were annealed with temperature variation of 300, 400, and 600 °C for 30 minutes. Characterization of material carried out in this study included the analysis of the microstructure by optical microscopy and Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS), and microhardness testing.

The results showed that the addition of Mn up to 9 wt.% to cartridge brass alloy led to the formation of second phase particles that are less rich in Zn and Mn content due to ordering tendency of Cu and Mn. The increase in the degree of deformation of 20, 40, and 70 % led to the decrease of second phase L/T ratio, each for 4, 11.6, and 18. There were also increase in the alloy hardness with the values of 68, 147, 171, and 205 HV respectively. The annealing process with temperature variation of 300, 400, and 600 °C led to the phenomena of recovery, recrystallization (dgrain ~ 5 μm), and grain growth (dgrain ~ 40 μm) that resulted in the decrease of hardness with the values of 201, 128, and 171 HV respectively. The effect of Mn addition in the cartridge brass alloy is to increase the hardness by solid solution and dispersion strengthening mechanisms and to decrease the rate of recrystallization, so it required higher annealing temperature and / or longer annealing time to reach full recrystallization."

"[Salah satu komponen terpenting pada peluru adalah selongsong yang memuat bubuk mesiu, primer, dan proyektil. Material yang umum digunakan untuk memfabrikasi selongsong peluru adalah cartridge brass (kuningan) yang mengandung 26-32 wt.% Zn. Selongsong peluru diproduksi dengan proses metalurgi yang kontinu, yang terdiri atas pengecoran, pencanaian, dan deep drawing. Dalam proses deep drawing biasanya ditemukan beberapa masalah mayor, seperti keretakan dan perobekan. Untuk meminimalisir masalah tersebut, pengembangan material dengan keuletan yang lebih baik menjadi penting untuk digunakan sebagai selongsong peluru. Mangan digunakan sebagai unsur paduan pada kuningan untuk meningkatkan keuletannya. Pada penelitian ini, paduan Cu-28Zn dengan penambahan 3,2 wt.% Mn difabrikasi dengan pengecoran gravitasi. Untuk menghomogenisasi komposisi kimia, paduan diberi perlakuan panas pada 800 oC selama 2 jam. Kemudian spesimen dicanai dingin dengan deformasi 20, 40, dan 70 % reduksi. Proses anil selanjutnya dilakukan setelah pencanaian dingin sebesar 70 % dengan temperatur 350, 400, dan 450 oC selama 15 menit. Karakteriasi material yang dilakukan pada penelitian ini terdiri dari analisis struktur mikro menggunakan mikroskop optik dan Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS), serta pengujian kekerasan mikro. Hasil penelitian menunjukkan bahwa peningkatan derajat deformasi sebesar 20, 40, dan 70 % menyebabkan butir menjadi semakin pipih dengan L/D ratio masing-masing bernilai sekitar 0,7, 2,2, 7,7, dan 14,1. Selain itu juga terjadi peningkatan nilai kekerasan spesimen, yakni sebesar 56, 127, 145, dan 207 HV secara berurutan. Sementara proses anil setelah canai dingin sebesar 70 % pada temperatur 350, 400, dan 450 oC menyebabkan terjadinya peristiwa stress relieve yang ditandai dengan fenomena recovery, diikuti dengan rekristalisasi (dgrain ~ 7 μm), hingga grain growth (dgrain ~ 14 μm). Selain itu juga terjadi penurunan nilai kekerasan spesimen, yakni sebesar 204, 131, dan 100 HV secara berurutan. Pengaruh penambahan unsur Mn di dalam paduan cartridge brass adalah meningkatkan nilai kekerasan dan memperlambat laju rekristalisasi, dibutuhkan temperatur anil yang lebih tinggi untuk mencapai rekristalisasi sempurna pada paduan cartridge brass dengan penambahan Mn.

---

One of the most important part of bullet is its cartridge shell which contains gun powder, primer, and projectile altogether. Common material used to fabricate bullet shell is cartridge brass which contains 26-32 wt.% Zn. Cartridge shell is produced by a continuous metallurgical processes, which are casting, rolling, and deep drawing. In deep drawing process, some major problems are typically found, such as cracking and tearing. In order to minimize these problems, it is essential to develop materials with enhanced ductility to be used as cartridge shell. Manganese is used as an alloying element of cartridge brass to increase its ductility. In this research, Cu-28Zn alloy with addition of 3,2 wt.% Mn were fabricated by gravity die casting. To homogenize the chemical composition, the alloy was heated at 800 °C for 2 hours. Afterwards, the specimens were cold-rolled with deformation of 20, 40, and 70 %. Subsequent annealing process after 70 % cold-rolled with temperature of 350, 400, and 450 oC for 15 minutes was carried out. Material characterizations consisted of microstructure analysis using optical microscope and Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS), and microvickers hardness testing. The result showed that higher degree of deformation of 20, 40, and 70 % led to more elongated grains with L/D ratio of 0.7, 2.2, 7.7, and 14.1, respectively. Moreover, the hardness of material increased with the increase in the level of deformation, with the values of 56.1, 126.6, 144.6, and 206.7 HV, respectively. Meanwhile, annealing at the temperatures of 350, 400, and 450 oC to specimens with prior deformation of 70 %, resulted in recovery and stress relieve, followed by recrystallization (dgrain ~ 7 μm), and finally grain growth (dgrain ~ 14 μm). Furthermore, the hardness of material decreased with the increase in level of annealing temperature, with the values of 204, 131, and 100 HV, respectively. The roles of Mn in the cartridge brass is to increase the hardness and to slower the recrystallization rate. In general, addition of Mn in cartridge brass increased the annealing temperatures needed to achieve full recrystallization.;One of the most important part of bullet is its cartridge shell which contains gun powder, primer, and projectile altogether. Common material used to fabricate bullet shell is cartridge brass which contains 26-32 wt.% Zn. Cartridge shell is produced by a continuous metallurgical processes, which are casting, rolling, and deep drawing. In deep drawing process, some major problems are typically found, such as cracking and tearing. In order to minimize these problems, it is essential to develop materials with enhanced ductility to be used as cartridge shell. Manganese is used as an alloying element of cartridge brass to increase its ductility. In this research, Cu-28Zn alloy with addition of 3,2 wt.% Mn were fabricated by gravity die casting. To homogenize the chemical composition, the alloy was heated at 800 °C for 2 hours. Afterwards, the specimens were cold-rolled with deformation of 20, 40, and 70 %. Subsequent annealing process after 70 % cold-rolled with temperature of 350, 400, and 450 oC for 15 minutes was carried out. Material characterizations consisted of microstructure analysis using optical microscope and Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS), and microvickers hardness testing. The result showed that higher degree of deformation of 20, 40, and 70 % led to more elongated grains with L/D ratio of 0.7, 2.2, 7.7, and 14.1, respectively. Moreover, the hardness of material increased with the increase in the level of deformation, with the values of 56.1, 126.6, 144.6, and 206.7 HV, respectively. Meanwhile, annealing at the temperatures of 350, 400, and 450 oC to specimens with prior deformation of 70 %, resulted in recovery and stress relieve, followed by recrystallization (dgrain ~ 7 μm), and finally grain growth (dgrain ~ 14 μm). Furthermore, the hardness of material decreased with the increase in level of annealing temperature, with the values of 204, 131, and 100 HV, respectively. The roles of Mn in the cartridge brass is to increase the hardness and to slower the recrystallization rate. In general, addition of Mn in cartridge brass increased the annealing temperatures needed to achieve full recrystallization., One of the most important part of bullet is its cartridge shell which contains gun powder, primer, and projectile altogether. Common material used to fabricate bullet shell is cartridge brass which contains 26-32 wt.% Zn. Cartridge shell is produced by a continuous metallurgical processes, which are casting, rolling, and deep drawing. In deep drawing process, some major problems are typically found, such as cracking and tearing. In order to minimize these problems, it is essential to develop materials with enhanced ductility to be used as cartridge shell. Manganese is used as an alloying element of cartridge brass to increase its ductility.

In this research, Cu-28Zn alloy with addition of 3,2 wt.% Mn were fabricated by gravity die casting. To homogenize the chemical composition, the alloy was heated at 800 °C for 2 hours. Afterwards, the specimens were cold-rolled with deformation of 20, 40, and 70 %. Subsequent annealing process after 70 % cold-rolled with temperature of 350, 400, and 450 oC for 15 minutes was carried out. Material characterizations consisted of microstructure analysis using optical microscope and Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS), and microvickers hardness testing.

The result showed that higher degree of deformation of 20, 40, and 70 % led to more elongated grains with L/D ratio of 0.7, 2.2, 7.7, and 14.1, respectively. Moreover, the hardness of material increased with the increase in the level of deformation, with the values of 56.1, 126.6, 144.6, and 206.7 HV, respectively. Meanwhile, annealing at the temperatures of 350, 400, and 450 oC to specimens with prior deformation of 70 %, resulted in recovery and stress relieve, followed by recrystallization (dgrain ~ 7 μm), and finally grain growth (dgrain ~ 14 μm). Furthermore, the hardness of material decreased with the increase in level of annealing temperature, with the values of 204, 131, and 100 HV, respectively.

The roles of Mn in the cartridge brass is to increase the hardness and to slower the recrystallization rate. In general, addition of Mn in cartridge brass increased the annealing temperatures needed to achieve full recrystallization.]"

"Munisi merupakan salah satu bagian esensial dari sebuah sistem persenjataan. Munisi bertugas sebagai penyimpan dan penyalur daya ledak yang dapat digunakan pada berbagai macam senjata api. Pada beberapa waktu yang lalu, PT. PINDAD mengimpor brass cup sebagai material dasar pembuatan selongsong peluru dalam jumlah besar. Namun ketika tahap manufaktur, bahan impor tersebut mengalami kegagalan mendekati 100% ketika proses lekuk botol. Untuk itu dikembangkanlah paduan cartridge brass yang mampu meningkatkan sifat mampu bentuk, elongasi dan mampu cor. Unsur paduan yang digunakan sebagai alloying element adalah Bismuth (Bi). Bismuth mampu meningkatkan pressure tightness, machinability dan castability paduan cartridge brass pada penambahan optimum. Pada penelitian ini, dikembangkan paduan cartridge brass dengan penambahan 0,1, 0,5 dan 1,0 wt. % Bi. Sampel difabrikasi melalui proses pengecoran gravitasi dengan dimensi 110 x 110 x 6 mm. Sampel kemudian dihomogenisasi selama 2 jam pada suhu 800 ˚C sebelum dikarakterisasi. Karakterisasi material yang dilakukan antara lain pengujian komposisi kimia paduan menggunakan Optical Emission Spectrometry (OES) analisis struktur mikro dengan menggunakan mikroskop optik dan Scanning Electron Microscope (SEM) dan analisis komposisi Energy Dispersive X-Ray (EDX), Hasil gambar struktur mikro dilakukan dengan Image Pro Analysis. Pengujian tarik dan keras juga dilakukan untuk mengetahui sifat mekanik dari paduan cartridge brass. Dari hasil pengujian ditemukan bahwa penambahan wt. % Bi meningkatkan jumlah segregasi Bi dan porositas pada paduan sebesar 1,2, 3,2 and 7,3 % untuk masing-masing komposisi 0,22, 0,41 dan 0,80 wt. % Bi. Pengamatan SEM mengkonfirmasi peningkatan jumlah segregasi Bi baik pada butir maupun batas butir seiring dengan meningkatnya wt. % Bi. Pengujian mekanik menunjukan hasil optimum pada komposisi 0,22 wt. % dengan kekuatan tarik, tegangan luluh dan elongasi masing-masing sebesar 209 MPa, 105 MPa dan 61 % serta hasil deterioratif pada komposisi 0,41 dan 0,80 wt. %. Pengamatan makro dan SEM ? EDX dari permukaan perpatahan mengkonfirmasi jenis perpatahan ulet dan segregasi Bi pada ketiga sampel.

---

Ammunition is one of the essential aspect of weaponry system. Ammunition acts as a storage and channel for explosive compound in firearms, creating sufficient momentum to expel the bullet. Recently, PT.PINDAD, an Indonesian state owned defense industry, imported cartridge brass in the form of brass cup, which experienced a near 100% failure upon manufacturing. Brass cups fractured before it reached the final form: ammunition?s shell. Hence, cartridge brass is alloyed to breed a new alloy which its castability, formability and elongation increased. In this research, Cartridge brass (Cu-28Zn) is alloyed with Bi, a post transition metal with similar properties of Pb yet non-toxic and environmentally safe. Bismuth addition promotes machinability, pressure tightness and castability. Produced by pre-simulated gravity die casting, a 99.99% pure copper, zinc and bismuth ingot were casted into Cu-28Zn-0,1, 0,5 and 1,0 Bi alloy with dimension of 110 x 110 x 6 mm3. The specimens were homogenized at 800˚C for 2 hours before characterized both mechanically and microstructurally. Chemical composition was tested using Optical Emission Spectrometry, microstructural examination was covered by Optical Microscope, Scanning Microscope Electron ? Energy Dispersive X-Ray analysis (SEM-EDX), image results was also processed by Image Pro Analysis software. Last but not least, Mechanical testing was done by tensile and hardness testing. Results implied that Bi addition increases the area fraction of Bi segregation in the amount of 1,2, 3,2 and 7,3 % for each 0,22, 0,41 and 0,80 wt.% Bi composition. SEM examination confirmed the increase of Bi segregation respective to the increase of Bi addition. Mechanical testing showed optimum value on 0,22 wt. % composition with tensile, yield strength and elongation of 209 MPa, 105 MPa and 61 % respectively while 0,41 and 0,80 wt.% Bi cartridge brass showed deteriorative effect. Macro and SEM ? EDX examination confrmed the vicinity of Bi segregation and ductile mode on fractured surface."

" ABSTRAK Berkembangnya kereta api sebagai moda transportasi massal yang murah dan cepat bukan berarti tidak meninggalkan masalah. Salah satu masalah yakni pada sistem pengereman yang kurang efektif dan efisien. Saat ini, blok rem kereta api menggunakan material besi tuang yang memiliki berat 11-12 kg dan umur pemakaian hanya mencapai satu bulan sehingga menyebabkan biaya operasional tinggi. Penelitian ini bertujuan membuat material alternatif blok rem kereta api berupa komposit Aluminium A356 berpenguat mikro Al2O3 dengan penambahan variasi penghalus butir TiB sebesar 0; 0,01; 0,0347; 0,0362; 0,0622; dan 0,0689 wt dengan penambahan 2 wt magnesium sebagai agen pembasahan menggunakan metode pengecoran aduk. Karakterisasi hasil pengecoran menggunakan pengujian tarik, keras, aus, impak, densitas, porositas, komposisi kimia OES dan XRD , mikrostruktur OM, SEM, dan EDX . Hasil pengujian menunjukkan penambahan TiB sebesar 0,0347 wt mampu mereduksi ukuran dan mengubah bentuk SDAS dari panjang dan kasar menjadi bulat dan halus sehingga meningkatkan kekuatan tarik, kekerasan, dan ketahanan aus secara signifikan, namun menurunkan elongasi dan harga impak.

---

ABSTRACT The development of train as a mode of mass transportation which are cheap and quick does not mean with no problem. One of the problems is the braking system is less effective and efficient. Nowadays, brake blocks train using cast iron material that weight up to 11 12 kg and life time only reached one month which causing high operating costs. This study aims to create an alternative material for brake blocks train in the form of Aluminium A356 reinforced micro Al2O3 composite material with the addition of grain refiner TiB of 0 0.01 0.0347 0.0362 0.0622 and 0.0689 wt with the addition of 2 wt magnesium as a wetting agent using stir casting method. Material characterization consisted of tensile testing, hardness testing, wear testing, impact testing, density and porosity testing, chemical composition testing OES and XRD , and microstructure testing OM, SEM and EDX . The test results showed that the addition of 0.0347 wt TiB capable of reducing the size and changing the shape of a long and coarse SDAS become round and fine that increasing tensile strength, hardness, and wear resistance significantly, but decreasing elongation and impact strength."