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"[ABSTRAKKomposit nano Al A356 berpenguat partikel Al2O 3 berpotensi untuk meningkatkan kekuatan sifat mekanis tanpa mengorbankan keuletan pada matriks. Pada penelitian ini dilakukan variasi penambahan fraksi volume dari partikel nano Al2O 3 sebesar yaitu 0.1%, 0.2%, 0.5%, 1%, dan 1,2%. Untuk meningkatkan kemampubasahan dari Al2O 3 pada Al A356 ditambahakn Mg sebesar 10%. Hasil penelitian menunjukkan bahwa komposit Al A356/Al2O 3 dengan 0.5% Vf memiliki sifat mekanis yang lebih baik daripada yang lain. Nilai kekuatan tariknya mencapai 140,3 MPa lalu elongasinya sebesar 9,563% dan kekerasannya mencapai 46,2 HRB. Akan tetapi nilai mekanis dari kekuatan tarik masih dibawah dari Al A356 As cast maupun Al 356. Fenomena ini disebabkan karena adanya porositas dan persebaran partikel nano yang tidak merata.ABSTRACTAluminium A356 nano composite reinforced with Al2O 3 particle have a potential to increase mechanical properties while maintaining good ductility. In this study, the addition %Vt variation of Al2O 3. Variation used is 0.1%, 0.2%, 0.5%, 1%, dan 1,2%. To improve wettability of Al2O 3 in Al A356 addes 10% Mg. The results showed that the composite Al A356 / SiC 0,5% Vf have better mechanical properties than others. The ultimate tensile strength reach 140.3 MPa with 9.56% elongation. Hardness value reach 46,2.1 HRB. However, the value of ultimate tensile strength is still below the mechanical Al A356 As cast and Al 356. This phenomenon is due to the porosity and bad particle dispersion.;Aluminium A356 nano composite reinforced with Al2O 3 particle have a potential to increase mechanical properties while maintaining good ductility. In this study, the addition %Vt variation of Al2O 3. Variation used is 0.1%, 0.2%, 0.5%, 1%, dan 1,2%. To improve wettability of Al2O 3 in Al A356 addes 10% Mg. The results showed that the composite Al A356 / SiC 0,5% Vf have better mechanical properties than others. The ultimate tensile strength reach 140.3 MPa with 9.56% elongation. Hardness value reach 46,2.1 HRB. However, the value of ultimate tensile strength is still below the mechanical Al A356 As cast and Al 356. This phenomenon is due to the porosity and bad particle dispersion.;Aluminium A356 nano composite reinforced with Al2O 3 particle have a potential to increase mechanical properties while maintaining good ductility. In this study, the addition %Vt variation of Al2O 3. Variation used is 0.1%, 0.2%, 0.5%, 1%, dan 1,2%. To improve wettability of Al2O 3 in Al A356 addes 10% Mg. The results showed that the composite Al A356 / SiC 0,5% Vf have better mechanical properties than others. The ultimate tensile strength reach 140.3 MPa with 9.56% elongation. Hardness value reach 46,2.1 HRB. However, the value of ultimate tensile strength is still below the mechanical Al A356 As cast and Al 356. This phenomenon is due to the porosity and bad particle dispersion., Aluminium A356 nano composite reinforced with Al2O 3 particle have a potential to increase mechanical properties while maintaining good ductility. In this study, the addition %Vt variation of Al2O 3. Variation used is 0.1%, 0.2%, 0.5%, 1%, dan 1,2%. To improve wettability of Al2O 3 in Al A356 addes 10% Mg. The results showed that the composite Al A356 / SiC 0,5% Vf have better mechanical properties than others. The ultimate tensile strength reach 140.3 MPa with 9.56% elongation. Hardness value reach 46,2.1 HRB. However, the value of ultimate tensile strength is still below the mechanical Al A356 As cast and Al 356. This phenomenon is due to the porosity and bad particle dispersion.]"

"Composite Al A6061 / SiC can be made through methods Stir Casting, this method has been used widely because has middle cost and able to distribute the SiC particle well. This research use variation of SiC, from 2%, 5%, 8%, 10%, and 15%. To enhance the wettability between particle and matrix, Mg 10% was added to the molten aluminium. The result showed that the addition of 10% SiC is optimum among others, with tensile strength reach 247,8 Mpa, elongation 7,04846 % and hardness 54,333 HRB. This mechanical properties is better than the Al A6061 as cast. From datas above, it can be concluded that the more SiC being added, will improve the mechanical properties of material. However, if SiC pass the optimum value, the SiC tend to agglomerated and will deterioriate the mechanical properties of Al A6061/SiC. ;Composite Al A6061 / SiC can be made through methods Stir Casting, this method has been used widely because has middle cost and able to distribute the SiC particle well. This research use variation of SiC, from 2%, 5%, 8%, 10%, and 15%. To enhance the wettability between particle and matrix, Mg 10% was added to the molten aluminium. The result showed that the addition of 10% SiC is optimum among others, with tensile strength reach 247,8 Mpa, elongation 7,04846 % and hardness 54,333 HRB. This mechanical properties is better than the Al A6061 as cast. From datas above, it can be concluded that the more SiC being added, will improve the mechanical properties of material. However, if SiC pass the optimum value, the SiC tend to agglomerated and will deterioriate the mechanical properties of Al A6061/SiC. ;Composite Al A6061 / SiC can be made through methods Stir Casting, this method has been used widely because has middle cost and able to distribute the SiC particle well. This research use variation of SiC, from 2%, 5%, 8%, 10%, and 15%. To enhance the wettability between particle and matrix, Mg 10% was added to the molten aluminium. The result showed that the addition of 10% SiC is optimum among others, with tensile strength reach 247,8 Mpa, elongation 7,04846 % and hardness 54,333 HRB. This mechanical properties is better than the Al A6061 as cast. From datas above, it can be concluded that the more SiC being added, will improve the mechanical properties of material. However, if SiC pass the optimum value, the SiC tend to agglomerated and will deterioriate the mechanical properties of Al A6061/SiC. "

"ABSTRAKPenambahan partikel nano SiC kedalam matriks Al6061 menghasilkan material komposit dengan kekuatan mekanis yang tinggi namun tetap mampu mempertahankan sifat ulet. Magnesium sebesar 10% Vf juga ditambahkan sebagai agen pembasah agar didapatkan ikatan yang kuat pada daerah antarmuka. Pada penelitian ini digunakan variasi penambahan partikel nano SiC sebesar 0,05%, 0,10%, 0,15%, 0,20% dan 0,30% untuk mengetahui titik optimal penambahan penguat. Hasil dari penelitian ini menunjukkan penambahan partikel nano SiC optimal di komposisi 0,15%, dengan kekuatan tarik 263,43 MPa, presentase elongasi 7,67%, kekerasan 56,5 HRB, dan harga impak sebesar 0,0550 J/mm2. Peningkatan kekuatan mekanis pada komposit dihasilkan dari kehadiran fasa penguat Mg2Si, distribusi partikel nano SiC yang merata, serta pembasahan yang baik antara matriks dan partikel penguat.

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ABSTRACTThe addition of nano SiC particles to Al6061 matrix has enhancing the mechanical properties of metal matrix composite while the ductility properties still maintained. 10% Vf of magnesium were used as wetting agent to achieve strong interface bonding. In the present work, Al6061 reinforced with various amounts (0,05%, 0,10%, 0,15%, 0,20% and 0,30%) of nano SiC were prepared. Results of this study shows the optimum content of nano SiC in Al6061 matrix were 0,15% Vf, with UTS (Ultimate Tensile Strength) reached 263,43 MPa, 7,67% elongation, hardness up to 56,5 HRB, and 0,0550 J/mm2 impact value. The enhancement of mechanical properties of Al6061/SiC composite were influenced by the presence of Mg2Si phase, good distribution of nano SiC particles, and also good interface bonding between matrix and reinforce.;"

"Paduan Al-Zn-Mg (Seri 7xxx) telah banyak dikembangkan dalam berbagai aplikasi, terutama dalam industri penerbangan sebab memiliki kekerasan yang tinggi sementara densitasnya rendah. Paduan tersebut umumnya diperkuat melalui perlakuan penuaan, di mana terjadi difusi atom-atom Zn dan Mg dari larutan padat sangat jenuh sehingga terbentuk presipitat metastabil. Selain itu, paduan dapat diperkuat pula dengan penambahan Ti yang akan memperhalus butir. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh Ti dalam penguatan presipitasi paduan Al-5.1Zn-1.8Mg-0.4Ti (% berat) pada berbagai temperatur. Paduan ini dibuat dengan proses squeeze casting. Kemudian dilakukan homogenisasi pada temperatur 400 oC selama 4 jam dan laku pelarutan pada 440 oC selama 1 jam yang dilanjutkan dengan pencelupan air hingga temperatur ruang. Penuaan dilakukan pada temperatur 90, 130 dan 200 oC selama 200 jam. Untuk mengetahui respon penuaan, dilakukan pengujian kekerasan Rockwell, sementara itu perubahan struktur mikro diamati dengan menggunakan Mikroskop Optik dan Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS). Hasil penelitian menunjukkan bahwa kekerasan tertinggi dihasilkan setelah penuaan di temperatur 90 oC, bahkan pada temperatur ini, kekerasan terus meningkat setelah 200 jam. Semakin tinggi temperatur penuaan, semakin rendah kekerasan puncak yang dihasilkan, tapi waktu yang dibutuhkan untuk mencapai kekerasan puncak akan berkurang. Penambahan Ti diketahui dapat menahan penguatan dengan memperlambat kinetika presipitasi melalui penurunan jumlah kekosongan kompleks zat terlarut. Urutan presipitasi yang terbentuk adalah GP zone  ƞ?  ƞ (MgZn2).

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Al-Zn-Mg alloys (7xxx series Al alloys) have been widely used in many applications, especially in aerospace industry because of their high strength and low density. These alloys are commmonly hardened upon ageing treatment, in which diffusion of Zn and Mg atoms from super saturated solid solution results in formation of metastable precipitates. To further increase the strength of the alloys, Ti is added to decrease the grain size. The objective of this study is to investigate the role of Ti in the precipitation strengthening of Al-5Zn-1.8Mg-0.4Ti (wt.%) alloy.

The alloy was fabricated by squeeze casting process. Then, the alloy was homogenized at 400 oC for 4 hours. Subsequent solution treatment was employed at 440 oC for 1 hour and followed by water quenching to room temperature. The ageing was conducted at 90, 130 and 200 oC for 200 hours. The ageing response was followed by Rockwell hardness testing, while the microstructural evolution was observed by using Optical Microscope (OM) and Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS).

The results showed that the highest hardness was achieved after ageing at 90 oC, and even at this temperature, the hardness remained increase after 200 h of ageing. The higher the ageing temperature, the lower the achieved peak hardness but the time needed to peak hardness reduced. Addition of Ti retarded the strengthening by slowering kinetics of precipitation through decreasing number of solute-vacancy complexes. The suggested major precipitation sequence was GP zones  ƞ?  ƞ (MgZn2)."

"Material komposit matriks aluminium grafit saat ini banyak digunakan karena sifatnya yang ringan dan memiliki kekuatan mekanis yang baik. Salah satu aplikasi yang mulai dikembangkan adalah untuk aplikasi tribologi, yakni material self-lubricating bearing dimana keunggulan material komposit ini ialah memiliki berat jenis yang ringan dibandingkan dengan material bronze bearing sehingga mampu menghemat penggunaan bahan bakar dari kendaraan. Pada penelitian ini digunakan material komposit matriks aluminium dengan penguat berupa grafit 1% Vf, dan tembaga 0,5% Vf sebagai wetting agent. Metode yang digunakan ialah metalurgi serbuk dengan tekanan kompaksi sebesar 300 bar, variabel temperatur sinter 500°C, 550°C, 600°C, 650°C, dan 700°C dengan waktu tahan sinter selama 60 menit. Penelitian ini bertujuan untuk menganalisa pengaruh temperatur sinter terhadap sifat mekanis dari material komposit aluminium grafit. Pengujian yang dilakukan adalah pengujian kekerasan (ASTM E-10), laju aus dengan metode Ogoshi, kuat tekan (ASTM E-9-89a), densitas dan porositas (ASTM 373-88), serta pengamatan struktur mikro dengan mikroskop optik dan SEM (Scanning Electron Microscope) dan uji komposisi dengan EDS (Energy Disperse Spectroscopy). Dari hasil pengujian didapatkan kondisi optimum pada temperatur sinter 700°C dimana nilai kekerasan mencapai 78 BHN, nilai laju aus mencapai 13,8 x 10^-6 mm³/mm, nilai kuat tekan mencapai 589 N/mm², nilai densitas mencapai 2,14 gram/cm³, dan nilai porositas mencapai 21,56%. Sedangkan dari hasil pengamatan struktur mikro menggunakan mikroskop optik dan SEM didapatkan adanya fasa intermetallic, dan pada pengujian komposisi menggunakan EDS didapatkan fasa matriks aluminium, Al₂O₃, dan intermetallic AlCu₂. Hasil ini membuktikan bahwa sampel reinforced sinter memiliki sifat mekanis yang lebih baik dibandingkan dengan sampel unreinforced maupun reinforced non sinter. Untuk aplikasi material bearing, nilai kekerasan dan laju aus yang didapat pada hasil penelitian ternyata masih belum memenuhi persyaratan. Oleh sebab itu, perlu dilakukan proses pengerasan lebih lanjut atau penambahan kadar grafit untuk meningkatkan sifat mekanis dari material komposit aluminium grafit.

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Nowadays, aluminum graphite composite has been widely use because of lightweight and good mechanical properties. One of the applications of using aluminum graphite composite is for tribological application, such as self lubricating bearing which is having an advantage that aluminum graphite composite has lower density than bronze bearing, so that it can reduce the using of fuels on the vehicles.

Material used in this experiment is aluminum matrix composite with 1% Vf graphite as a reinforced, and 0.5% Vf copper as a wetting agent. Powder metallurgy was used as a method to make an aluminum graphite composite material. Using pressure of 300 bars and sintering temperature variable from 500°C, 550°C, 600°C, 650°C to 700°C for 60 minutes. The aim of experiment is to analyze the effect of sintering temperature on mechanical properties of aluminum graphite composite. Mechanical tests are hardness testing (ASTM E-10), wear rate testing with Ogoshi technique, compression testing (ASTM E-9-89a), density and porosity. Micro structure was analyzed both optical microscope and scanning electron microscope (SEM), while energy disperse spectroscopy (EDS) to analyze the chemical composition of phases produced during sintering.

The optimum condition was sintering temperature at 700°C with hardness of 78 BHN, wear rate of 13,8 x 10^-6 mm3/mm, compression of 589 N/mm², density 2,14 gram/cm³, and porosity 21,56%. Meanwhile, micro structure analyzed using optical microscope and SEM found an intermetallic phase, it is confirmed by EDS which is the micro structure containing of aluminum matrix phase, Al₂O₃, and intermetallic AlCu2.

These results prove that reinforced sinter sample has better mechanical properties than unreinforced and reinforced non sinter sample. Indeed for bearing material application, the hardness and wear rate in this experiment has not yet achieved. That is why, need further process to harden the material or by increasing the graphite content."

"Retak dingin merupakan salah satu kendala yang sering terjadi pada pengelasan baja tahan aus. Skripsi ini berisi tentang penelitian pengaruh preheat dan perbedaan kawat las terhadap ketahanan retak dan sifat mekanis dari baja tahan aus CREUSABRO® 8000 dengan menggunakan pengelasan Shielded Metal Arc Welding (SMAW). Elektroda yang digunakan adalah elektroda E 7018 dan MG NOX 35. Sampel terdiri dari 6 buah plat CREUSABRO® 8000 yang dilas dengan elektroda E 7018 dan MG NOX 35. Proses preheat dilakukan dengan menggunakan burner pada hasil sambungan dengan varibel tanpa preheat, preheat 150°C, preheat 250°C. Berdasarkan hasil analisa data, penerapan perlakuan preheat pada temperatur 150°C dan 250°C tidak mengakibatkan adanya retak dingin pada hasil lasan. Selain itu, perlakuan preheat dan penggunaan elektroda MG NOX 35 mampu meningkatkan sifat mekanis pada hasil lasan. Perlakuan preheat dan pemilihan elektroda memberikan pengaruh signifikan terhadap terjadinya retak dingin dan sifat mekanis serta dapat dijadikan salah satu metode pengendalian retak dingin pada pengelasan baja tahan aus CREUSABRO® 8000.

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Cold cracking is the one of problem on wear resistance plate welding. On this project consist of reseach on influence preheating treatment and welding electrode in crack resistance and mechanical properties of CREUSABRO® 8000 wear resistance steel with SMAW process. Welding electrodes that be used are E 7018 and MG NOX 35. All of sample consisted of 6 CREUSABRO® 8000 wear resistance steel plates that be joined with E 7018 and MG NOX 35 electrode. The process of preheat is done by using burner with 3 joining for each variable consisting of without preheat, preheat 150°C, dan preheat 250°C.

Based on the results of data analysis, cold cracking is not consist to the application of preheat at 150°C and 250°C. Application of preheat and MG NOX 35 electrode also can improve mechanical properties of weld area. Application preheating and selection of welding electrode provides a significant influence on cold cracking and mechanical properties as well as can be used as a method of controlling cold cracking in welding of CREUSABRO® 8000 wear resistance steel."

"Pada industri bangunan kapal, pengelasan merupakan metode yang sangat umum dipakai untuk melakukan penyambungan pelat-pelat baja. Di galangan, juru las menggunakan besar arus dan kecepatan pengelasan yang bervariasi. Seringkali alasan yang sering dipakai adalah untuk mengejar deadline pengerjaan kapal sehingga sesuai dengan timeline yang telah direncanakan. Ada juga dengan motivasi yang kurang bisa dipertanggungjawabkan, yaitu agar pekerjaan cepat selesai. Fenomena yang biasa terjadi adalah kuat arus dinaikkan dari standar galangan atau kecepatan pengelasan ditingkatkan menjadi lebih tinggi. Hal ini mempengaruhi kualitas sambungan akhir, seperti perbedaan struktur makro dan mikro hasil las yang selanjutnya berimplikasi pada sifat-sifat mekanis material. Penelitian ini bertujuan untuk mencari hubungan antara parameter proses MMAW terhadap struktur makro hasil las serta hubungannya dengan sifat mekanis material baja berkekuatan tarik tinggi setelah proses pengelasan. Parameter pengelasan yang dipakai adalah kuat arus dan kecepatan pengelasan. Arus las yang dipakai dalam penelitian ini adalah 110 A yang merupakan standar galangan, 120 A, dan 130 A sedangkan kecepatan pengelasan divariasikan berdasarkan kecepatan pengelasan normal (yang biasa dipakai juru las), dipercepat, dan diperlambat dari kecepatan pengelasan normal. Hasil pengelasan tersebut diuji di laboratorium untuk memperoleh foto struktur makro sambungan material setelah melalui proses pengelasan. Dari foto struktur makro, akan diperoleh analisis perubahan struktur makro pada material yang selanjutnya akan dihubungkan terhadap sifat-sifat mekanis akhir material. Penelitian ini nantinya akan memperlihatkan parameter pengelasan optimum yang akan digunakan pada industri bangunan kapal (galangan) untuk membangun kapal.

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In ship building industry, welding is a very common method used to establish joining plates of steel. In the shipyard, welder often use vary large current and travel speed. Frequently, the reason often used is to pursue the construction deadline so that the vessel in accordance with the timeline. There is also lack of motivation that can be accounted for, such as speedy completion. A common phenomenon is welding currents of shipyard standard raised or welding speed increased becomes higher than the normal. This affects the quality of the final joining, such as differences in the macro-structur and micro-structur of welds which would have implications for the mechanical properties of the material.

This study aimed to explore the relationship between process parameters MMAW against the macro-structure of welds and its relationship with the mechanical properties of high tensile strength steel material after the welding process. Welding parameters used are welding currents and welding speed. Welding currents used in this study was 110 A which is a standard of shipyard, 120 A, and 130 A while welding speed was varied by normal welding speed (which is usually used by welder), accelerated and slowed from the normal welding speed.

Welds are tested in the laboratory to obtain macro-structure photo of the joining after the welding process. From the photo, it will be obtained the analysis of changes macro-structure of the material which would be linked to the mechanical properties of the final material then. This study will show the optimum welding parameters to be used in the ship building industry (shipyard) to build the ship."

"Friction stir welding merupakan jenis pengelasan solid state dengan memanfaatkan gesekan dari tool yang berputar sebagai sumber panas untuk menyambung logam. Selain metode pengelasan ini tidak memerlukan logam pengisi dan gas pelindung, metode ini efektif untuk mengelas logam berbeda, salah satunya adalah antara aluminium dengan tembaga yang akan sangat berguna untuk aplikasi komponen listrik. Friction stir welding pada penelitian ini diaplikasikan untuk mengelas aluminium 6061 dengan tembaga murni menggunakan variasi kecepatan putar tool sebesar 600, 1000, 1200, 2000 rpm. Perbedaan kecepatan putar tool tersebut diberikan untuk mengetahui pengaruhnya terhadap makrostruktur, mikrostruktur, konduktivitas listrik, dan kekerasan sambungan. Mikrostruktur diamati menggunakan mikroskop optik. Uji konduktivitas listrik dilakukan menggunakan alat uji mikro ohmmeter dan pengujian kekerasan dilakukan menggunakan alat uji mikro-vickers. Hasil penelitian memperlihatkan bahwa semakin besar kecepatan putar tool, masukan panas yang terjadi semakin meningkat sehingga cacat void yang terbentuk semakin sedikit. Masukan panas yang semakin meningkat juga menghasilkan nilai konduktivitas listrik sambungan menurun. Selain itu, nilai kekerasan sambungan meningkat seiring dengan meningkatnya kecepatan putar tool. Hal ini terjadi akibat semakin banyaknya senyawa intermetalik yang terbentuk.

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Friction stir welding is a solid-state welding method that utilizes friction from a rotating tool that becomes a heat source for joining the metals. Besides this welding method does not require filler metal and gas shielding, it is effective for welding dissimilar metals such as aluminium and copper which would be very useful in electrical components applications. Friction stir welding in this research was used for joining aluminium 6061 to pure copper using various tool rotational speed of 600, 1000, 1200, and 2000 rpm. Those different tool rotational speed was given to determine its effect on macrostructure, microstructure, electrical conductivity, and joints hardness. The microstructure was observed using an optical microscope. The electrical conductivity test was carried out using a micro ohmmeter and the hardness test was carried out using a microhardness vickers testing machine. The results shows that the higher the tool rotational speed applied, the higher heat input gained, so that fewer voids were formed. The increasing heat input also made the electrical conductivity value of the joints decreased. Besides that, the joints hardness value increased with the increasing tool rotational speed. It occurred because more intermetallic compounds formed."

"ABSTRAKPaduan Cu-Zn 70/30 atau dikenal juga sebagai Cartridge Brass memilikisifat konduktivitas panas dan listrik yang sangat baik, ketahanan korosi yangtinggi, serta kemampubentukan yang baik. Cu-Zn 70/30 sangat luas digunakansebagai core dan tank radiator otomotif, komponen amunisi, maupun perangkatbangunan dan arsitektur sehingga sangat rentan sekali terpapar oleh lingkunganyang korosif seperti air laut dan ammonia. Thermo-Mechanical ControlledProcessing (TMCP) adalah salah satu metode rangkaian pengontrolan pemanasandan pembentukan dengan tujuan meningkatkan kualitas sifat material. Olehkarena itu, pada penelitian ini digunakan metode TMCP dengan canai hangatuntuk meningkatkan sifat mekanik dan ketahanan korosi paduan Cu-Zn 70/30.Proses canai dilakukan dengan metode bolak-balik dengan deformasi sebesar 60%(30%-30%) dimana pada setiap pass-nya paduan Cu-Zn dipanaskan terlebihdahulu pada temperatur 300oC dengan waktu tahan berbeda mulai dari 30, 60, dan120 menit. Berdasarkan hasil penelitian didapatkan kesimpulan bahwa dengansemakin lamanya waktu pemanasan dan kemudian dideformasi lebih lanjut makaterjadi penurunan ukuran butir dari 92.2 μm menjadi 36.5 μm yang berpengaruhpada peningkatan kekerasan sebesar 174.12 HV dan kekuatan tarik mencapai525.4 MPa pada waktu tahan 120 menit. Selain itu, semakin lama waktupemanasan juga memberikan perilaku korosi yang berbeda pada dua lingkungankorosif. Pada lingkungan air laut (NaCl 3.5%), paduan kuningan cenderungmengalami penurunan laju korosi hingga 0.0218 mm/yr untuk weight loss dan0.1404 mm/yr untuk polarisasi. Sedangkan pada lingkungan ammonia (Mattsson?sSolution) terjadi hal yang berkebalikan dimana paduan kuningan cenderungmengalami kenaikan laju korosi hingga mencapai 0.1906 mm/yr untuk weight lossdan 5.1209 mm/yr untuk polarisasi. Ditambah lagi, terdapat indikasi adanyafenomena Anneal Hardening karena tersegregasinya atom terlarut pada dislokasiatau batas butir sehingga memberikan pengaruh yang cukup signifikan terhadapnilai kekerasan, kekuatan tarik, dan ketahanan korosi paduan Cu-Zn 70/30.

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ABSTRACTCu-Zn alloy (70/30) also known as Cartridge Brass possesses high thermaland electrical conductivity, high corrosion resistance, and good formability. Thus,used extensively for core and tank automotive radiator, ammunition component,and architectural hardware. This wide applications are susceptible to exposure ofcorrosive environments such as seawater and ammonia environments. Thermo-Mechanical Controlled Processing (TMCP) is one method consists of controlledheating and controlled forming to produce high quality materials. Therefore, thisresearch focuses on the study of mechanical properties and corrosion resistanceCu-Zn 70/30 by implementing warm rolling TMCP method. Rolling process wasconducted in reversible way with deformation degree of 60% (30%-30%) andbefore each pass of the rolling the material is heated up to temperature 300oC withdifferent holding time from 30, 60, and 120 minutes. The results showed that asthe longer holding time of the heating and was continued by further deformation,it affects the grain size to be much smaller from 92.2 μm to 36.5 μm and thuscorresponds to the increasing of hardness value up to 174.12 HV dan UltimateTensile Strength (UTS) up to 525.4 MPa for 120 minutes of holding time. On theother hand, the longer holding time of heating, it gives brass different behaviour intwo different corrosive environments. In the seawater environment (NaCl 3.5%),brass tend to have lower corrosion rate in value of 0.0218 mm/yr and 0.1404mm/yr for weight loss and polarization respectively. On the contrary, in theammoniacal environment (Mattsson?s Solution) brass tend to have highercorrosion rate with value up to 0.1906 mm/yr and 5.1209 mm/yr for weight lossand polarization respectively. In addition, it indicates that Anneal Hardeningcaused by segregation of solute atoms into dislocations or grain boundary hastaken place that affect a significant change in hardness, tensile strength, andcorrosion resistance of Cu-Zn 70/30."