Articles
<![CDATA[HIGH TEMPERATURE GAS NITRIDING TREATMENT OF AISI 430 USING LOW AND HIGH PURITY NITROGEN GAS ]]>
<![CDATA[Suprihanto, Agus]]>
<![CDATA[ ROTASI Vol 18, No 3 (2016): VOLUME 18, NOMOR 3, JULI 2016 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.18.3.65-68
<![CDATA[The properties of stainless steels can be improved by high temperature gas nitriding (HTGN) treatment. The improving of their properties are obtained from nitrogen atom which diffuse into stainless steel. Nitrogen gas is the main source of nitrogen atom on the HTGN treatment. Generally, these treatment use high purity of nitrogen gas. The aim of this research is to investigate the effect of nitrogen gas purity on the HTGN treatment for AISI 430. Stainless steel AISI 430 plate 2 mm thick was processed by HTGN treatment. The specimens was exposed at nitrogen gas atmosphere at temperature 1200oC and held for 2 hours prior quenching in water. The treatment used industrial/welding grade (99.5%) as low nitrogen gas purity and ultra high purity (UHP) grade (99.999%) as high nitrogen gas purity. The vickers micro-hardness test was conducted to evaluate the hardness distribution from surface into middle section of the specimens before and after treatment. Light optical microscope was applied to examine the microstructure of specimens after treatment. Metallographic examination shows both treatments using low and high purity gas have the same grain size. However HTGN treatment using low purity of nitrogen gas produces hardness slightly lower than the high purity. This is due the high content of impurity of the low purity gas that reduces the partial pressure of nitrogen gas. Another effect of impurity is the reaction between nitrogen gas and its impurity especially oxygen gas. These reactions reduce the amount of free nitrogen atom which diffuses on the stainless steel.]]>
<![CDATA[PENGEMBANGAN METODE PENINGKATAN KEKERASAN BAJA TAHAN KARAT AISI 316L LEWAT PROSES NITRIDASI GAS TEMPERATUR TINGGI ]]>
<![CDATA[Umardhani, Yusuf]]>;
<![CDATA[Suprihanto, Agus]]>
<![CDATA[ ROTASI Vol 15, No 1 (2013): VOLUME 15, NOMOR 1, JANUARI 2013 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.15.1.7-10
<![CDATA[Stainless steel AISI 316L merupakan salah satu material teknik yang digunakan sebagai biomaterial terutama untuk aplikasi implan tulang. Upaya perbaikan sifat mekanisnya sangat diperlukan untuk meningkatkan kehandalannya. Penelitian ini bertujuan untuk mengembangkan teknologi nitridasi gas temperatur tinggi (high temperatur gas nitriding/HTGN) guna meningkatkan kekerasan AISI 316L. Teknik yang digunakan adalah dengan mengekspose spesimen stainless steel 316L berukuran 50mm x 100mm x2mm dalam atmosfer nitrogen pada temperatur T = 1000oC, 1100oC dan 1200oC dan t = 15menit, 30menit dan 60menit. Dengan proses tersebut atom nitrogen dapat berdifusi ke dalam spesimen dan membentuk larutan padat interstisi pada sel satuan Fe sehingga akan emningkatkan kekerasannya. Spesimen yang telah dinitridasi dilakukan pengujian kekerasan mikro. Pengujian kekerasan mikro menggunakan metode mikro Vickers yang bertujuan untuk mengetahui distribusi kekerasan searah ketebalan spesimen. Hasil penelitian menunjukkan bahwa semakin tinggi temperatur dan semakin lama waktu penahanan menyebabkan kekerasan dipermukaan spesimen meningkat hampir 75% yaitu dari 143VHN menjadi 249VHN yaitu untuk temperatur proses 1200oC dan waktu 60menit. Peningkatan kekerasan yang diperoleh mengindikasikan bahwa ketahanan korosi akibat gesekan (freeting corrosion) dan ketahanan ausnya meningkat]]>
<![CDATA[ANALISIS CACAT COR PADA PROSES PENGECORAN BURNER KOMPOR (STUDI KASUS DI PT. SUYUTI SIDO MAJU, CEPER) ]]>
<![CDATA[Sulardjaka, Sulardjaka]]>;
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Wahyudi, P]]>
<![CDATA[ ROTASI Volume 12, Nomor 3, Juli 2010 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.12.3.27-33
<![CDATA[Objective of this research is to analysis casting defect in burner casting process. The research have been conducted in Small Medium Enterprise PT. Suyuti Sido Maju. Casting deffects were observeb by visual inspection. There are some casting deffect such as : cold shut, shearing and void. Composition of casting product, pouring temperature and characterization of sand casting have been done to investigate the casting process that caused casting deffect]]>
<![CDATA[PENGARUH PENAMBAHAN UNSUR Cr DAN Cu TERHADAP KEKUATAN TARIK BESI COR KELABU FC20 ]]>
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Satrijo, Djoeli]]>;
<![CDATA[Suratman, Rochim]]>
<![CDATA[ ROTASI Volume 9, Nomor 1, Januari 2007 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.9.1.17-24
<![CDATA[The mechanical properties of grey cast iron are influenced by cooling rate, thickness of casting, heat treatment,liquid treatment and alloying. Some aplications of its materials need high strength grey cast iron. To improve itstensile strength usually its added with unsures which known as carbide promoteur ie. Cr and Cu.In these research the effect of Cr and Cu on the mechanicals properties of grey cast irons has been evaluated.Base material FC 20 which alloyed with Cr 0,23 %, 0, 32% and 0,47% and Cu between 0,6% to 0,7% have beentested. The tensile test and metallographyc examinations have been conducted to known of its efects.From tensile test there is an improvement of tensile strength about 20% from 191MPa to 232MPa. However themicrostructure of specimens are same which are pearlitic grey cast irons, with graphite type VII (flake), Adistributions and size of graphite are 3-5.]]>
<![CDATA[Magnetic Properties of Austenitic Stainless Steel 316l and 316lvm after High Temperature Gas Nitriding Treatment ]]>
<![CDATA[Suprihanto, Agus]]>
<![CDATA[ ROTASI Vol 19, No 2 (2017): VOLUME 19, NOMOR 2, APRIL 2017 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.19.2.72-75
<![CDATA[Biometallic materials for implant devices not only have to good corrosion resistance but also stable nonmagnetic properties. Various method have been developed for enhanced the corrosion resistance i.e low temperature gas nitriding treatments. Unfortunatelly, low temperature gas nitriding produce weakly ferromagnetic due the presence of expanded austenitic phases. Another treatments methods which is capable for improvement the mechanical properties is high temperature gas nitriding. However, the evaluation of magnetic properties of austenitic stainless steel 316L and 316LVM not yet investigation. The evaluation of magnetic properties of austenitis stainless steel 316L and 316LVM after high temperature gas nitriding treatments have been succesfully done. The magnetic properties are evaluated by vibrating sample magnetometre (VSM) test. The magnetic properties such as magnetic remenance, magnetic saturation and magnetic permeability are improved. As treated 316L and 316LVM have more stable non-magnetic properties and they more safe and compatible for MRI test]]>
<![CDATA[PENGUJIAN MEKANIK DAN FISIK PADA METAL MATRIX COMPOSITE (MMC) ALUMINIUM FLY ASH ]]>
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Setyana, Budi]]>
<![CDATA[ ROTASI Volume 8, Nomor 4, Oktober 2006 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.8.4.50-57
<![CDATA[Fly ash (abu terbang) merupakan salah satu hasil sisa (limbah) batubara yang diperoleh dari penyaringan gas yang dikeluarkan dari saluran pembuangan pada suatu power plant. Berton-ton fly ash yang semakin menumpuk setiap tahunnya dibiarkan begitu saja sehingga menimbulkan polusi bagi lingkungan bahkan manusia. Oleh sebab itu diperlukan solusi untuk menaggulangi masalah ini. Penelitian yang dilakukan menunjukkan bahwa ternyata fly ash ini mempunyai sifat fisik dan kimia yang berguna dalam material konstruksi dan industri. Aluminium yang merupakan salah satu material yang banyak digunakan manusia di jadikan sebagai matriks bagi pemanfaatan fly ash yang salah satunya berfungsi sebagai partikel penguat (reinforcement). Penggunaan fly ash ini diharapkan dapat meningkatkan sifat mekanik dari aluminium. Untuk mengetahui seberapa besar pengaruh penambahan fly ash ini terhadap sifat mekanik aluminium maka dalam tugas sarjana ini dilakukan pengujian tarik, impak dan kekerasan, sedangkan pengujian koefisien muai linear, konduktivitas termal dan densitas dilakukan sebagai pengujian sifat fisik, dimana sebelumnya dilakukan proses pembuatan komposit aluminium fly ash dengan metode stir casting. Dengan mengunakan variasi awal persentase berat fly ash sebesar 5%, 10% dan 15%, dapat diketahui bahwa nilai kekuatan tarik, impak dan kekerasan cenderung meningkat seiring dengan semakin besar persentase penambahan fly ash dan terjadi penurunan nilai koefisien muai, konduktivitas termal dan densitas seiring dengan semakin besar persentase penambahan fly ash]]>
<![CDATA[PENGARUH PENAMBAHAN KROMIUM DAN TEMBAGA TERHADAP KEKUATAN LELAH BESI COR KELABU ]]>
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Suratman, Rochim]]>
<![CDATA[ ROTASI Volume 8, Nomor 1, Januari 2006 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.8.1.1-7
<![CDATA[The mechanical properties of grey cast irons can be modified with alloying elements. Cr and Cu have beenknown as elements that can improve tensile strength of grey cast irons. The improvement of tensile strength can beinfluence of fatigue strength. The goal of this research is to study the effect of alloying Cr and Cu on the fatiguestrength.Four materials of grey cast irons have been conducted to high cycle fatigue testing on the rotating bendingmachine. The first material is grey cast irons without added Cr and Cu, and the other have added. The percentages ofCr have been added are 0,23% wt, 0,32%wt and 0,47%wt and Cu 0,6%wt to 0,7%wt. The metallographyc examinationsand tensile test also have been conducted.The result of this research are the material has the same microstructure. The microstructures of its materials arepearlitic grey cast irons with graphite type VII, distribution A and size of graphite 3-5. The tensile, endurance andfatigue strength of materials, which added Cr and Cu significantly rising, compared with base materials. The tensilestrength rose from 191MPa to 232MPa and the endurance strength raised from 94 MPa to 110MPa. However threemodified materials, which added Cr, and Cu has the same effects.]]>
<![CDATA[Dampak Kemiringan Dinding Silo Terhadap Distribusi Tegangan Dinding pada Corrugated Steel Silo Berkapasitas 4650 Ton ]]>
<![CDATA[Widyanto, Susilo Adi]]>;
<![CDATA[Sukamta, Sukamta]]>;
<![CDATA[Yurianto, Yurianto]]>;
<![CDATA[Suprihanto, Agus]]>
<![CDATA[ ROTASI Vol 20, No 2 (2018): VOLUME 20, NOMOR 2, APRIL 2018 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.20.2.89-94
<![CDATA[Konstruksi silo dirancang untuk menyimpan butiran. Idealnya sumbu vertikal silo maupun dindingnya tegak lurus terhadap bidang dasarnya sehingga beban dinding hanya berupa gaya radial akibat ketinggian kolomnya. Miringnya konstruksi silo menyebabkan terjadinya beban gabungan pada dinding pada arah kemiringannya. Paper ini membahas pengaruh kemiringan konstruksi silo pada gaya yang bekerja pada dinding. Silo yang diobservasi dengan kapasitas penyimpanan sebesar 4650 ton, dengan diameter 19 m dengan ketinggian 20 m. Dari hasil pemodelan FEM, distribusi tegangan pada dinding yang berbeda ketebalannya relatif lebih besar dibandingkan tegangan yang terjadi pada dinding ganda pada bagian dibawahnya. Tegangan maksimum terjadi pada daerah sambungan baut antara dinding dan stiffener. Pada kemiringan 10o tegangan maksimum dinding mencapai sekitar 45 kg/mm2 baik pada dinding ganda maupun di lokasi dinding yang berbeda ketebalannya.]]>
<![CDATA[PROSES REHEATING BILLET DAN THIXOCASTING PADUAN Al-18Si BERSTRUKTUR NON-DENDRITIC ]]>
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Satrijo, Djoeli]]>
<![CDATA[ ROTASI Volume 9, Nomor 2, April 2007 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.9.2.12-24
<![CDATA[One of the important steps in semi-solid forming (SSF) especially thixoforming is the reheating process to achieve the required semisolid state of the billet. The reheating process is not only necessary to achieve the required semi-solid state of the billet, but also to control the microstructure of the billet. In the reheating process, billets are heated up to the temperature between the solidus and liquidus of the alloy to obtain accurately controlled solid fraction and spherical particles uniformly dispersed. The process variables such as reheating time, reheating temperature, reheating holding time, and induction heating power have much effects on the quality of the reheated billets. It is difficult to consider all the variables at the same time to predict the billet quality. In this paper, the process variables focused on reheating temperature and reheating holding time to see the correlation relationship between the process variables and the conditions of the billet quantitatively, and then simulate the thixocasting process to know the correlation relationship between the process variables and properties of the materials, which is the flow ability of the billet and the hardness of the thixocasting products. The alloys used in this experiment is non-dendritic Al-18Si alloy which formed used mechanical stirring method.]]>
<![CDATA[The relationship between heel pad compressibility index, age, body mass index and foot area contact in calcanea spur patients ]]>
<![CDATA[Wibowo, Dwi Basuki]]>;
<![CDATA[Suprihanto, Agus]]>;
<![CDATA[Haryadi, Gunawan Dwi]]>
<![CDATA[ ROTASI Vol 22, No 3 (2020): VOLUME 22, NOMOR 3, JULI 2020 ]]>
Publisher : <![CDATA[Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro ]]>
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DOI: 10.14710/rotasi.22.3.188-193
<![CDATA[This study was performed to investigate the relationship between heel pad compressibility index (HPCI), age, body mass index (BMI) and (FAC) for calcanea/heel spur patients. Thirteen patients with a symptomatic heel spur (3 males and 10 females) participated in this study. The HPCI increased with age and HPCI of the elderly is greater than the adult. The HPCI increased with pain minimum compressive pressure (PMCP) indicated HPCI are all significantly greater in patients with plantar heel pain than in normal subjects. The BMI increased with FAC is caused by BMI and FAC of males is greater than females. The PMCP decreased with BMI indicated that patient with excessive body mass will make experience more pain. The result of pain measurement showed that there are 7 patients who indicated the abnormality (the PMCP value is lower than 2 kg/cm2). From this study, it can be concluded that the quantitatively pain level is worst when PMCP< 2.0 kg/cm2, it is severe when 3.0> PMCP ≥ 2.0 kg/cm2 and it is moderate when PMCP≥3.0 kg/cm2]]>
