Hasil Pencarian  ::  Simpan CSV :: Kembali

"Contents : - Chapter 1: Introduction - Chapter 2: Aluminum casting alloys - Chapter 3: Aluminum casting processes - Chapter 4: The effects of microstructure on properties - Chapter 5: The influence and control of porosity and inclusions in aluminum Castings - Chapter 6: Hot isostatic processing - Chapter 7: Heat treatment of aluminum castings - Chapter 8: Properties and performance of aluminum castings - Data Set 1: Aging response curves - Data Set 2: Growth curves - Data Set 3: Stress-strain curves - Data Set 4: Tensile properties at high and low temperatures and at room- Temperature after high-temperature exposure - Data Set 5: Creep rupture properties - Data Set 6: Rotating-beam reversed-bending fatigue curves - Appendix 1: Glossary of terms - Appendix 2: Abbreviations and symbols - Appendix 3: Test specimen drawings - Subject index - Alloy index "

"Penelitian ini mempelajari pengaruh penambahan partikel nano ZrO2 pada paduan Fe-18Al-5Cr-5Mn terhadap kekerasan, struktur mikro, porositas dan laju korosi melalui proses pemaduan mekanik yang dikuti proses kompaksi, sintering, anil dan hot pressing. Pengujian kekerasan, struktur mikro dengan mikroskop optik, SEM-EDAX, XRD dan porositas diaplikasikan pada paduan yang dihasilkan. Dari hasil pengujian menunjukkan kekerasan tertinggi dihasilkan pada paduan dengan komposisi Fe-18Al-5Cr-5Mn-3ZrO2 dengan ratio ball mill 20:1, waktu milling 6 jam, tekanan kompaksi 100 kg/mm2, temperatur sinter 1000 °C selama 2 jam sebesar 207.32 HVN. Sementara pada proses hot pressing, kekerasan tertinggi pada dihasilkan dari paduan Fe-18Al-5Cr-5Mn-5ZrO2 dengan kekerasan 250 HVN dan pada proses mechanical milling kekerasan tertinggi didapatkan dari paduan Fe-18Al-5Cr-5Mn-2ZrO2 dengan kekerasan 515 HVN. Sedangkan struktur mikro paduan Fe18Al5Cr5Mn yang ditambahkan partikel nano ZrO2 memiliki fasa intermetalik FeAl, α-(Fe,Mn), α-Cr dan partikel ZrO2. Hasil refinement pola difraksi untuk paduan Fe-Zr1, Fe-Zr2 dan Fe-Zr3 didapatkan weighted R profile (Rwp) dan godness of fit (c2) berturut-turut adalah 21,42 dan 1,31, 24,19 dan 1,69 dan 21,08 dan 1,25 dengan fasa FeAl dan α-Cr. Persen berat kedua fasa ini berubah seiring dengan penambahan partikel nano ZrO2 1 wt.% didapatkan fasa FeAl sebesar 82,3 wt.% dan fasa α-Cr sebesar 17,7 wt.% sementara paduan Fe-Zr2 dan Fe-Zr3 dengan penambahan partikel nano masing masing 2 dan 3 wt.% menunjukkan kecendrungan fasa FeAl berkurang dan fasa α-Cr meningkat dengan fasa FeAl sebesar 71,8 dan 51,6 wt.% dan 28,2 dan 48,4 wt.%. Laju oksidasi dan ketebalan oksida dipengaruhi oleh temperatur dan waktu oksidasi dengan laju oksidasi paling rendah yaitu sampel oksidasi 1 jam 900 oC sebesar 0,00023 mpy yang kategori outstanding dan ketebalan oksida 97,96 μm. Morfologi oksida yang terbentuk pada sampel terdiri atas oksida Fe2O3 dan Al2O3 pada lapisan oksida luar, oksida Fe2O3 dan Al2O3 pada lapisan antarmuka dan oksida Al2O3, Cr2O3, Fe2O3 dan fasa FeAl pada substrat.

---

This research studied the effect of adding ZrO2 nanoparticles to Fe-18Al-5Cr-5Mn alloy on hardness, microstructure, porosity and corrosion rate through a mechanical alloying process followed by compaction, sintering, annealing and hot pressing processes. Hardness, microstructure with an optical microscope, SEM-EDAX, XRD and porosity testing were applied to the resulting alloy. The results showed that the highest hardness was produced in an alloy with the composition Fe-18Al-5Cr-5Mn-3ZrO2 with a ball mill ratio of 20:1, milling time of 6 hours, compaction pressure of 100 kg/mm2, sintering temperature of 1000 °C for 2 hours of 207.32 HVN. While in the hot pressing process, the highest hardness was obtained from the Fe-18Al-5Cr-5Mn-5ZrO2 alloy with a hardness of 250 HVN and in the mechanical milling process the highest hardness was obtained from the Fe-18Al-5Cr-5Mn-2ZrO2 alloy with a hardness of 515 HVN. Meanwhile, the microstructure of the Fe18Al5Cr5Mn alloy with added ZrO2 nanoparticles has FeAl, α-(Fe,Mn), α-Cr and ZrO2 particles as intermetallic phases. The refinement results for the diffraction patterns for the Fe-Zr1, Fe-Zr2 and Fe-Zr3 alloys obtained the weighted R profile (Rwp) and godness of fit (c2) respectively 21.42 and 1.31, 24.19 and 1, respectively. 69 and 21.08 and 1.25 with FeAl and α-Cr phases. The weight percentage of these two phases changed with the addition of 1 wt.% ZrO2 nanoparticles, which resulted in a FeAl phase of 82.3 wt.% and an α-Cr phase of 17.7 wt.%, while the Fe-Zr2 and Fe-Zr3 alloys with the addition of particles nano respectively 2 and 3 wt.% showed a tendency for the FeAl phase to decrease and the α-Cr phase to increase with the FeAl phase of 71.8 and 51.6 wt.% and 28.2 and 48.4 wt.%. Oxidation rate and oxide thickness are affected by temperature and oxidation time with the lowest oxidation rate, namely the 1 hour 900 oC oxidation sample of 0.00023 mpy which is in the outstanding category and the oxide thickness is 97.96 μm. The morphology of the oxide formed in the sample consisted of Fe2O3 and Al2O3 oxides on the outer oxide layer, Fe2O3 and Al2O3 oxides on the interfacial layer and Al2O3, Cr2O3, Fe2O3 and FeAl phases on the substrate."

"Rasio kekuatan dan densitas aluminium yang tinggi serta ketahanan aluminium yang tinggi terhadap korosi membuat aluminium menjadi material yang populer digunakan oleh industri aviasi. Sebagai salah satu aplikasinya, aluminium kerap digunaakn sebagai komponen pada helikopter. Menurut Rashid, dkk rotor adalah komponen yang paling rentan pada helikopter. Lalu Weber, dkk mengatakan bahwa 65% pilot pernah menerbangkan helikopter dengan kondisi rotor yang rusak. Banyaknya faktor yang dapat menyebabkan kerusakan pada rotor mempersulit penemuan solusi untuk kegagalan komponen. Ketangguhan patah adalah ketahanan suatu material akan perambatan retak. Penambahan laju retak dapat terjadi karena beberapa mekanisme seperti fatigue, creep, kesalahan pemilihan material, SCC, dan lainnya. Karena itu, rekayasa material mengenai ketangguhan patah menarik sangat menarik untuk dipelajari. Metode eksperimental trial and error untuk rekayasa material memerlukan banyak waktu panjang, biaya tinggi, dan akurasi penelitian yang sangat ditentukan oleh kemampuan peneliti. Metode pembelajaran mesin regresi menggunakan data dokumentasi terdahulu sehingga dapat memangkas waktu dan biaya untuk rekayasa material. Pada penelitian ini berhasil dikembangkan model pembelajaran mesin dengan menggunakan algoritma XGBoost. Kemampuan prediksi cukup baik, dibuktikan dari perbandingan nilai aktual dan prediksi serta nilai metrik model sebesar 0,906.

---

The high strength-to-density ratio and corrosion resistance of aluminum have made it a popular material in the aviation industry. One of its applications is in helicopter components. According to Rashid et al., the rotor is the most vulnerable component in a helicopter. Furthermore, Weber et al. stated that 65% of pilots have flown helicopters with damaged rotors. The numerous factors that can cause rotor damage make finding solutions to component failures challenging. Fracture toughness is the resistance of a material to crack propagation. Increased crack propagation can occur due to various mechanisms such as fatigue, creep, material selection errors, SCC (Stress Corrosion Cracking), and others. Therefore, studying fracture toughness in materials engineering is highly interesting. Traditional trial-and-error experimental methods for materials engineering require extensive time, high costs, and research accuracy heavily dependent on the abilities of the researchers. Regression machine learning methods using past documentation data can help reduce time and costs in materials engineering. In this study, a machine learning model using the XGBoost algorithm was successfully developed. The predictive capability was quite good, as evidenced by the comparison between actual and predicted values, as well as a model metric value of 0.906. "

"Piston pada motor adalah komponen dari mesin pembakaran dalam yang berfungsi sebagai penekan udara masuk dan penerima hentakan pembakaran pada ruang bakar cylinder liner. Material penyusun piston tersebut adalah aluminium AC8H yang sifatnya ringan, kuat, dan tahan aus. Dalam proses pengecoran paduan aluminium, penambahan modifier dan perlakuan panas merupakan proses yang dapat mempengaruhi sifat mekanis coran paduan. Sifat mekanis yang dimaksud adalah kekerasan, kekuatan tarik, keuletan serta keausan.Penelitian ini bertujuan untuk mengetahui kemungkinan penggantian proses perlakuan panas T6 (artificial ageing) yang merupakan standar dari proses pembuatan piston dengan proses penambahan modifier dan kemungkinan mempersingkat proses perlakuan T6 (artificial ageing) dengan proses T4 (natural ageing). Penelitian dilakukan dengan melebur ingot AC8H yang kemudian ditambahkan modifier stronsium dalam ladle. Jumlah kandungan stronsium yang dihasilkan setelah proses penambahan modifier adalah sebesar 0,00072% Sr, 0,0068% Sr, 0,0133% Sr dan 0,031% Sr. Hal yang sama dilakukan dengan menambahkan modifier phospor, dimana kandungan phospor yang dihasilkan menjadi 0,0036% P,0,0038% P, 0,0041% P dan 0,0046% P. Pada perlakuan panas setelah proses pengecoran, hasil ascast dilakukan proses T6 (artificial ageing) dan T4 (natural ageing) dengan pengamatan 0 jam, 24 jam, 48 jam , 72 jam, 96 jam dan 120 jam. Masing masing sampel hasil percobaan diatas dilakukan pengujian karakterisasi struktur mikro dan sifat mekanis.Hasil pengujian menunjukkan bahwa penambahan 0,031 % Sr dan Proses perlakuan panas T4 (natural ageing) 96 jam dan 120 jam setelah quenching memiliki sifat mekanis yang telah masuk range standar kualifikasi komponen piston. Dalam implementasi hasil ini masih harus dilanjutkan dengan uji coba melalui proses engine dyno test.

---

Piston is motor components of the engine which works as a press incoming air and recipient burning fuel in the cylinder liner space. Material of aluminum piston is AC8H that are lightweight, strong, and wear resist. In the process of casting aluminum alloy, adding modifiers and heat treatment is a process that can affect the mechanical properties as cast alloy. Mechanical properties of the object is referred to hardness, tensile strength, elongation and wear resistance.This research aims to find out the possibility of replacing the T6 heat treatment process (artificial ageing), as standard process of making a piston with the addition of modifiers and possibility to shorten the treatment T6 (artificial ageing) with the T4 (natural ageing). Research conducted by melt ingot AC8H then added Strontium in ladle. Strontium added that the amount until contain 0.00072% Sr, 0.0068% Sr, 0.0133% Sr, and 0.031% Sr. The same is done by adding Phospor until contain 0,0036% P, 0.0038% P, 0.0041% P and 0.0046% P. In the heat treatment process sample after casting will be process with T6 and T4 observation 0 hour, 24 hours, 48 hours, 72 hours, 96 hours and 120 hours. Each sample of an experiment conducted over the microstructure characterization and mechanical properties test.The test results indicate that the addition of 0.031% Sr. and heat treatment process T4 (natural ageing) 96 hours and 120 hours after quench as mechanical properties have already entered the qualifying standard range of part-piston. Implementation of the experiment must be continued to engine dyno test process before mass production."

"Aluminium adalah material yang banyak digunakan dalam industri otomotif karena sifatnya yang ringan, kuat dan tahan korosif. Salah satu penggunaanya untuk komponen cylinder head, komponen ini menggunakan jenis paduan aluminium AC4B dengan proses low pressure die casting. Namun produk yang dihasilkan dalam proses pengecoran ini banyak ditemukan kegagalan seperti porositas, penyusutan (shrinkage) yang menyebabkan kebocoran.Dari permasalahan tersebut maka dilakukan penelitian yaitu dengan penambahan titanium kedalam aluminium AC4B yang bertujuan untuk menigkatkan sifat mekanis dan meminimalisasi kegagalan pada komponen cylinder head yang dihasilkan. Penelitian ini secara khusus ditujukan untuk mempelajari pengaruh variasi persentase titanium (0.019 wt % dan 0.029 wt %) terhadap penghalusan butir aluminium AC4B dengan proses low pressure die casting. Kemudian menguji sampel cylinder head dengan uji tarik, uji kekerasan, pengukuran besar dendrite arms spacing dan menganalisa mikrostuktur dengan mikroskop optik dan dengan SEM dan EDS, serta pengujian bocor.\Penambahan penghalus butir sebesar 0.019 wt % Ti dan 0.029 wt % Ti pada aluminium AC4B meningkatkan kekuatan tarik sebesar 13.4 % dan 20.1 % dengan bentuk perpatahan getas. Sementara, nilai kekerasan juga mengalami peningkatan dengan panambahan titanium. Pada bagian tipis, penambahan 0.019 wt % Ti dan 0.029 wt % Ti meningkatkan nilai kekerasan sebesar 3.06 % dan 5.65 %. Pada bagian tebal, penambahan 0.019 wt % Ti dan 0.029 wt % Ti meningkatkan nilai kekerasan sebesar 2.14 % dan 5.19 %. Untuk besar dendrite arms spacing terjadi penurunan dengan penambahan titanium. Pada bagian tipis, panambahan 0.019 wt % Ti dan 0.029 wt % Ti menurunkan besar DAS sebesar 29.3 % dan 48.5 %. Pada bagian tebal, dengan penambahan 0.019 wt % Ti dan 0.029 wt % Ti menurunkan besar DAS sebesar 6.67 % dan 28.6 %. Pada pengamatan mikrostruktur menggunkan SEM tidak ditemukannya fasa Al3Ti. Untuk hasil uji bocor terdapat cylinder head yang mengalami bocor. Penambahan 0.019 wt % Ti dan 0.029 wt % Ti tidak terlalu efektif untuk mengurangi kegagalan shrinkage dan bocor pada komponen cylinder head tapi dapat mengurangi kegagalan karena blow hole.

---

Aluminum is the material most used in automotive industry because of light, good strength and corrosion resistant. One of the application of aluminum is used for cylinder head component, this component use aluminum alloy AC4B with low pressure die casting process. But the product in casting process much have failure such as porosity and shrinkage which cause leakage.This experiment was conducted to counter these problems with addition of titanium to increase mechanical properties and minimize reject from cylinder head manufacturing. The subject of this research was to study the effect of 0.019 wt. % and 0.029 wt. % titanium addition on grain refinement of AC4B alloy produced with low pressure die casting. Cylinder head samples were tested with tensile test, hardness test, dendrite arms spacing observation. Microstructure analysis was performed with optical microstructure and SEM/EDS, and also leakage test.Grain refiner addition of 0.019 wt. % Ti and 0.029 wt. % Ti increased tensile strength 13.4 % and 20.1 % with brittle fracture. Meanwhile, hardness value also increased with the addition of titanium. On thin parts, addition of 0.019 wt % Ti and 0.029 wt % Ti increased hardness value for 3.06 % and 5.65 %. On thick parts, the addition of 0.019 wt % Ti and 0.029 wt % Ti increased hardness value for 2.14 % and 5.19 %. The addition of titanium decreased dendrite arms spacing value. On thin parts, the addition of 0.019 wt % Ti and 0.029 wt % Ti decreased DAS value for 29.3 % and 48.5 %. On thick parts, the addition of 0.019 wt % Ti and 0.029 wt % Ti decreased DAS value for 6.67 % and 28.6 %. Al3Ti was not found with microstructure analysis using SEM. On leakage test, there were some cylinder head that exhibit leakage. On 0.019 wt % Ti there were 5 cylinder head that experience leakage, or 6.25 % and on 0.029 wt % Ti addition there were 8 cylinder head that experience leakage, or 10 %.On leakage test, there are several cylinder head that exhibit shrinkage. The addition of 0.019 wt % Ti and 0.029 wt % Ti were not very effective in decreasing shrinkage failure and leakage on cylinder head component, but effective in decreasing failure caused by blow hole."

"ABSTRAKPaduan aluminium AA5083 merupakan jenis paduan aluminium yang sering digunakan untuk konstruksi badan kapal khususnya untuk kapal patroli atau kapal-kapal cepat. Untuk proses penyambungan pada konstruksi lambung kapal pada umumnya digunakan metode pengelasan gas metal arc welding (GMAW). Kekuatan hasil pengelasan sangat penting khususnya ketangguhan terhadap retakan (crack toughness), dikarenakan operational dari kapal cepat tersebut. Pada penelitian ini dilakukan pengelasan paduan aluminium AA5083 dengan ukuran 150 mm x 350 mm , dengan ketebalan 15 mm dan 20 mm. Metode pengelasan dengan gas metal arc welding dengan dua logam pengisi yang berbeda yaitu ER5183 dan ER5356 dan gas pelindung yang digunakan adalah 99% argon.Hasil penelitian diperoleh bahwa maksimum nilai ketangguhan retak didapatkan pada pengelasan dengan material tebal 15 mm dengan logam pengisi ER5356 dan masukan panas 7.8 kj/cm.

---

ABSTRACTAluminium alloys AA5083 is alloys which mostly used in the hull components of ship and high speed craft. Normally gas metal arc welding (GMAW) are used for joining the construction. Welding strength especially crack toughness is very important on this welding due to normal operation of the ship or high speed craft. On this research welding of aluminium alloys AA5083 with dimension 150 mm x 350 mm and thickness 15 mm and 20 mm, were carried out by gas metal arc welding method using two difference filler metal ER5183 and ER5356, and 99% argon are used as shielding gas.The result of experiment that the maximum value of crack toughness was shown on welding with thickness plate 15 mm using filler metal ER5356 and heat input 7.8 kj/cm."

"The anodizing process was conducted in an Al7xxx aluminum alloy with silicon carbide which yielded a non-uniform thickness of anodic film with cavities, micro-pores and micro-cracks within it. This phenomenon occurred due to the presence of Silicon Carbide (SiC) particles within the Aluminum Matrix Composite (AMC), which impedes the initiation and growth of the protective anodic alumina oxide layer. Therefore, cerium sealing has been considered as the cheapest and simplest post treatment to remedy the poor anodic alumina oxide film in order to further enhance the corrosion resistance in aggressive circumstances. This paper examined the protection effect of an integrated layer which was composed of an anodized oxide layer and cerium deposits on an Al7075/SiC composite. Electrochemical Impedance Spectroscopy (EIS) was used to examine the corrosion protection effect and the corrosion behavior of an integrated layer in 3.5% sodium chloride (NaCl) solution at room temperature. In this study, anodizing of Al7075/SiC was carried out in a sulfuric acid H2SO4 solution at current density values of 15, 20, and 25 mA/cm2, respectively at room temperature, 0oC and -25oC for 30 minutes. Subsequently, cerium sealing was conducted in a cerium choloride plus hydrogen peroxide (CeCl3.6H2O + H2O2) solution at room temperature and pH 9 for 30 minutes. The best protection effect was found for Al7075/SiC, anodized at 0oC. Field Emission-Scanning Electron Microscope (FE-SEM) examination confirmed that the enhancement of corrosion resistance was due to the cerium deposit formed on the entire surface of the oxide anodized layer."

"Aluminum alloys, such as A6061-T6, are widely used in engineering components. However, detailed knowledge is needed to understand the way they respond to a fracture due to mechanical loading. Fractures occur in the structural component from crack propagation, and it is important to understand the mixed mode fracture behavior of crack growth. In this research, mixed mode fracture testing was conducted on the aluminum alloy A6061-T6 by employing a compact tension shear specimen. Crack growth behavior was investigated by applying a quasi-static loading at a constant cross-head speed using a Servopulser universal testing machine. The crack growths were observed by a Keyence digital microscope, and the critical stress intensity factors of the material were examined. Results showed that the shear type of crack initiation preceded the opening-type fracture. The dimple-type fracture on the fracture surface occurred under mode I and mixed mode with a loading angle of about 60o and 75o, respectively. The transition of crack initiation behavior from the opening-type fracture to the shear-type fracture occurred at a loading angle from 15o to 30o. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode at a loading angle 60o and 75o, respectively, for the compact tension shear specimen. Crack propagation behavior with three small holes occurring in a zigzag pattern ahead of the crack tip showed that crack initiation and propagation occurred only in the opening-type fracture. The experimental data followed the maximum hoop stress criterion under mode I and mixed mode with a lower mode II component at a loading angle of 75o. When the small holes occured inline, there were two types of fractures occurring: an opening fracture at crack initiation and then crack propagation caused by shear fracture."

"ABSTRAKResistance Spot Welding (RSW) merupakan proses menyambung logam dengan menggunakan arus dan sifat physical properties logam. Sehingga diperlukan gabungan analisis Electrical-Themal-Mechanical untuk mempelajari hasil las yang memiliki qualitas yang baik. Untuk memprediksi besar nugget las, simulasi RSW model 2D axissymetric dikembangkan dengan menggunakan sifat dari Electrical Contact Resistace (ECR). Tujuan penelitian ini adalah mempelajari pengaruh initial value ECR dan ketebalan ECR terhadap formasi nugget las. Variasi parameter pada penelitian ini adalah arus, ketebalan permukaan kontak, dan initial value ECR. Pada penelitian ini menunjukan bahwa untuk mendapatkan hasil nugget las yang berbentuk elips dan dapat menyambung antar plat metal yaitu dengan menentukan initial value ECR dan ketebalan ECR pada permukaan kontak antar plat metal (Al-Al) lebih besar dibandingkan dengan permukaan plat metal dan elektroda (Al-Cu). Setelah melakukan perbandingan dengan hasil experimen, simulasi RSW dengan menggunakan arus 8 kA dan initial value ECR dari permukaan kontak antar plat metal (Al-Al) dan plat - elektroda (Al-Cu) yaitu 230-28.75 µΩ memiliki selisih rata-rata 4.8 %. Dengan gaya elektroda 500 N dan expansi thermal yang terjadi pada specimen, stress maksimal yang dihasilkan sebesar 4 GPa.

---

ABSTRACTResistance Spot Welding (RSW) is a process of joining metals using current and the physical properties of metals. A coupled of Electrical-Thermal-Mechanical analysis is needed to study welding results that have good quality. To predict the size of the welding nugget, the RSW simulation of the 2D axisymmetric model was developed using the properties of the Electrical Contact Resistance (ECR). The purpose of this study was to investigate the effect of the initial value ECR and ECR thickness on the formation of weld nuggets. The parameter variations in this study were current, contact surface thickness, and initial value of ECR. The results of this study showed that in order to achieve weld nuggets that could join metal sheets with ellipse formation weld nugget, the simulation used initial value ECR and ECR thickness of between metal sheets (Al-Al) greater than the contact surface of metal sheet and electrode (Al-Al). By making comparisons with experimental results, welding simulations by using 8 kA current and the initial ECR value of the contact surface between metal sheets (Al-Al) and the metal sheet-electrode (Al-Cu) with 230-28.75 µΩ, had an average error of 4.8%. By using electrode force 500 N and occurring thermal expansion, the maximum generated stress was 4 GPa."