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Abstrak :
Perubahan struktur mikro baja karbon rendah menyebabkan terjadinya perubahan sifat. Perubahan ini sangat dipengaruhi oleh bentuk dan jenis pengerjaan (perlakuan) yang diberikan atau yang dialami oleh baja tersebut, bentuk dan jenis pengerjaan umumnya berupa pengerjaan panas atau pengerjaan dingin. Telah dilakukan penelitian pada konstruksi sambungan las dari bahan lembaran baja karbon rendah spesifikasi Ship Plate BKI Grade "A" hasil pengerolan panas produksi PT. Krakatau Steel, dengan menggunakan las SMAW dalam kondisi arus dan kecepatan pengelasan yang konstan. Dalam penelitian ini diambil dua jenis spesimen yang berbeda masing-masing spesimen yang tidak mengalami proses pengelasan dengan variasi sudut antara arah roll dan arah sumbu panjang spesimen masing-masing diambil 0° , 45° dan 90° dan spesimen yang mengalami proses pengelasan dengan variasi sudut arah roll terhadap arah las, masing-masing diambil 0° , 45° dan 90°. Pada penelitian ini dilakukann pengujian mekanik antara lain uji tarik, uji kekerasan, uji impact, pengukuran besar butir, uji metalografi, uji kekasaran permukaan, uji korosi serta struktur fasa dan bentuk butir. Berdasarkan hasil pengujian tersebut diatas didapatkan kekuatan tarik terbesar (6u) = 46,33 kg/mm2, kekuatan luluh (ay) = 31,74 kg/mm2 elongation (e) = 41,66 %, kekuatan impact (HI) = 1,525 J/mm2, kekerasan (Hv) = 200 pengurangan massa (R) = 1,212 mm/yr dan kekuatan tarik terkecil (6u) = 37,76 kglmm2, kekuatan luluh (ay) = 27,02 kg/mrn2, elongation (e) = 09,50 %, kekerasan (Hv) = 160,70, kekuatan impak (HI) = 0,0128 J/mm2 dan pengurangan massa (R) = 0,0641 mm/yr. ......The change of microstructure low carbon steel to cause alteration property. This alteration very influenced by model treatment quality which receiving or to experienced by steel mentioned this type or sort working was generally hot working which cold working. The investigation or-welding joint construction according to material low carbon steel spesification "Ship Plate BKI Grade A" hot rolling produce PT. Krakatau steel with applying SMAW weld in current condition and welding speed which constant According to investigation used two speciment type which to differ severally that not to experience welding proms for angle variation direction gap to rolling and and length pith speciment to take severally 0°, 45° and 90° and the speciment which to experience welding process with rolling direction to wards weld metal course, for severally to used 0°, 45° dan 90°. According to this investigation to executed mechanic testing among ather things tension test, hardness test impact test grain measuring, metallography test surface roughness test and corrosion test, besides from that possible too grain model and fasa structure° To be found result test mentioned to find the highest tension stress (au) = 46,33 kg/mm2, yield stress (cy) = 31,74 kglmm2, elongation (e) = 41,66 %, impact stress (Hi) = 1,525 J/mm2, hardness (Hv) = 2110 and to decrease of mass (R) = 1,212 mm/yr, and the lowest tension stress (cu) = 37,76 kg/mm2, yield stress (ay) = 27,02 kg/mm2, elongation (e) = 09,50 %, hardness (Hv) = 160,70, impact stress (HI) = 0,0128 J/mm2, and to decrease of mass (R) = 0,0641 mm/yr.

Abstrak :
Tesis ini membahas hubungannya pengaruh durasi (umur pakai) stainless steel AISI 409 terhadap IGC (Intergranular Corrosion) yang dapat menurunkan kualitas lasan dan pengaruh penambahan proses post weld pada proses pengelasan terhadap terbentuknya IGC (Intergranular Corrosion). Penelitian ini menggunakan uji tarik, uji kekerasan, pengamatan metalografi dan SEM, serta uji korosi dengan metode weight loss. Hasil penelitian menyimpulkan bahwa perpustakaan perlu dilibatkan dalam pengembangan kurikulum; materi pendidikan pemakai perpustakaan harus dikembangkan sesuai dengan komponenkomponen yang ada dalam information literacy; perpustakaan juga harus menyediakan sarana dan fasilitas yang mendukung peningkatan literacy mahasiswa. ...... This thesis discusses the relationship influences the duration (lifetime) of stainless steel AISI 409 on the IGC (intergranular corrosion) which can degrade the quality of welds and the effect of the addition of post-weld process on the welding process of the formation of the IGC (intergranular corrosion). This study used a tensile test, hardness test, metallographic and SEM observations, as well as corrosion test by the method of weight loss. The research concludes that the library should be involved in curriculum development; library user education materials should be developed in accordance with the components were present in the information literacy; the library must also provide facilities that support improved student literacy.

Abstrak :
Perubahan struktur mikro daerah las baja karbon rendah menyebabkan terjadinya perubahan dan perbedaan sifat ketahanan korosi. Tingkat ketahanan korosi secara tidak langsung dipengaruhi oleh bentuk dan jenis pertakuan atau pengerjaan yang telah dialami sebelumnya. Untuk meningkatkan pengawasan terhadap kerusakan yang diakibatkan oleh korosi pada daerah sambungan las maka dilakukan penelitian tingkat ketahanan korosi pada daerah logam las (WM), daerah logam induk (BM) dan daerah terpengaruh panas (BM-HAZ, HAZ, WM-HAZ) dengan menggunakan bahan dari baja karbon rendah hasil canai panas yang telah mengalami proses pengelasan. Hasil penelitian menunjukkan adanya perbedaan tingkat ketahanan korosi antara masing-masing daerah disekitar sambungan las. Tingkat ketahanan tertinggi terjadi pada daerah logam las (WM) spesimen WM.2 dan tingkat ketahanan korosi terendah terjadi pada daerah berbutir halus (HAZ) spesimen WM.3.

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The change of microstructure in the welding joint region of low carbon steel more often to cause difference in corrosion resistance- Corrosion resistance indirectly is influenced by the heat treatment or fabrication procedure. Improving fabrication procedure is necessary to prevent deleterious effect of corrosion in the welding joint area. Therefore in this investigation corrosion resistance in the weld metal area (WM), heat affected zone area (HAZ) as well as base metal (BM) become prime concern. The materials used in this investigation come from hot rolled process. The result indicated the different corrosion resistance between WM, BM and HAZ in the weld joint area. Highest corrosion resistance was found in the WM area while low corrosion resistance is the HAZ area.

Abstrak :
Material baja G10180 umum digunakan sebagai sampel kupon untuk memonitor proses korosi baja karbon. Pada berbagai literatur menyebutkan bahwa laju korosi baja karbon dalam larutan natrium klorida akan mencapai nilai maksimum pada konsentrasi NaCl sekitar 3,5% berat Evaluasi laju korosi material G10180 dilakukan dengan menggunakan metode analisa Tafel untuk lingkungan air tawar, NaCl 1%, 2%, 3%, 3,5% dan 4% berat, serta laju korosi yang didapat akan dibandingkan dengan laju korosi baja API 5L Grade-B. Hasil pengujian menunjukkan bahwa dalam lingkungan NaCl pada sistem terbuka dengan temperatur 27°C dan tekanan 1 atm, proses korosi baja G10180 lebih dipengaruhi aktivitas reaksi anodik daripada reaksi katodiknya. Jika dibandingkan dengan baja API 5L Grade-B, laju korosi baja G10180 yang didapatkan dari pengujian ini hampir sebesar 2,5 kali dari nilai laju korosi baja API 5L Grade-B. ......GI0180 steels commonly used as corrosion coupon for carbon steel monjtoring process. In many literature stated that carbon Steel corrosion rate in sodium chioride solution will reach maximum value around 3%wt NaCl G10180 corrosion rate evaluation done by using Tafel analysis method in tap water, 1%, 2%, 3%, 3.5% and 4%wt NaCl solution, and also will be compared with API 5L Grade-B corrosion rate. The results showed that in open system NaCl solution with 1 atm and 27°C, G10180 corrosion process determined by its anodic reaction activity compared to its cathodic reaction. If compared with the API 5L Grade-B Steel, the G10180 corrosion rate almost 2.5 times larger than API 5L.

Abstrak :
Tujuan : Penelitian ini bertujuan untuk mengamati ketahanan korosi dari TAD berbahan SS setelah pemaparan pada tiga jenis larutan kumur yang berbeda yang ditinjau dari permukaan topografi dan komposisi atomik. Metode : 28 unit TAD berbahan Stainless Steel dibagi secara merata ke dalam 4 kelompok larutan kumur (sodium fluoride 0,2%, povidone iodine 1%, kitosan 1,5%, dan air destilasi) yang masing-masing terdiri dari 7 unit TAD. Setelah 3 bulan perendaman dilakukan evaluasi ketahanan korosi material TAD SS menggunakan scanning electrone microscope (SEM) untuk melihat topografi permukaan dan energy-dispersive x-ray spectroscopy (EDS) untuk melihat komposisi atomik pada permukaan logam TAD SS. Hasil : Uji SEM menunjukkan tidak terdapat perbedaan bermakna antara permukaan TAD SS setelah pemaparan dalam larutan sodium fluoride, povidone iodine, dan larutan kontrol (air destilasi) yaitu permukaan menjadi kasar dan terbentuk korosi lubang/intergranular. Namun pada TAD SS yang direndam dalam larutan kitosan hanya mengalami perubahan permukaan menjadi kasar tanpa disertai korosi lubang/intergranular. Sementara uji EDS menunjukkan tidak terdapat perbedaan antara komposisi atomik TAD berbahan logam stainless steel setelah dipaparkan dalam larutan Fluoride, povidone iodine, kitosan, dan air destilasi (kontrol). Kesimpulan : Perendaman TAD SS 316L pada ketiga larutan kumur memicu proses korosi yang terlihat dari kekasaran permukaan logam paska perendaman, dengan larutan sodium fluoride dan povidone iodine bersifat lebih korosif, sementara larutan kitosan yang paling tidak korosif. TAD SS 316L memiliki biokompatibilitas yang baik terlihat dari pelepasan ion nikel dan kromium yang minimal pada seluruh sampel TAD SS paska perendaman. ......Objectives : This study aims to evaluate the corrosion resistance of stainless steel TAD after immersion in three mouthwash solutions marked by topography surface and atomic composition. Methods : 28 unit stainless steel TADs were divided into 4 group of mouthwashes (0,2% sodium fluoride, 1% povidone iodine, 1,5% chitosan, and distilled water as control group) each consisting of 7 TADs. After 3 months of immersion, the corrosion resistance of SS TAD will be evaluated using scanning electron microscope (SEM) to analyze the surface topography and energy-dispersive x-ray spectroscopy (EDS) to analyze the atomic composition. Results: SEM images showed no significant difference between the surface topography of SS TAD after immersion in sodium fluoride, povidone iodine, and distilled water as they exhibit surface roughness and the presence of pitting/intergranular corrosion. However, SS TAD immersed in chitosan solution only displayed surface roughness without any sign of pitting/intergranular corrosion. EDS examination showed no significant difference between the atomic composition of SS TAD immersed in all mouthwash solutions. Conclusions : Immersion of SS TAD 316L in three different mouthwashes induced corrosion process which is shown by the surface roughness after 3 months of immersion. Sodium fluoride and povidone iodine mouthwash have shown to be more corrosive, while chitosan mouthwash was the least corrosive. SS TAD 316L displayed good biocompatibility which is shown by minimal release of nickel and chromium ions on all TAD samples after immersion

Abstrak :
Since inhibition is the simplest mechanism used for mitigating the corrosion of metals and alloys, particularly in acidic environments, the present work aims to investigate the inhibiting effect of N-benzyl-N?-phenyl thiourea (BPTU) and N-cyclohexyl-N?-phenyl thiourea (CPTU) on mild steel corrosion in 0.1M HCl medium using the Tafel extrapolation technique. Tafel experiments were conducted with ±250 mV vs. rest potential (RP) in steps of 20 mV from the cathodic side for recording the corrosion currents, and then, the Tafel plot of potential vs. current was drawn for determining the corrosion current density (icorr). The linear polarization method was also used for validating the Tafel results. It was performed by polarizing the specimen with ±20 mV vs. RP in steps of 5 mV, and the corrosion currents were noted. The plot of potential vs. current was drawn for calculating icorr. The study reveals that both BPTU and CPTU act as anodic inhibitors for mild steel in the HCl medium, and good inhibition efficiency (>97%) was evidenced from both the compounds even at elevated temperatures. The study also reveals that the investigated compounds get adsorbed quickly on the steel surface, following Temkin’s adsorption isotherm. The kinetic parameters obtained from the study indicated that the inhibition was governed by a chemisorption mechanism and the presence of inhibitors substantially reduced the metal dissolution in the studied temperature range. The investigation shows that there was a good correlation between the Tafel extrapolation and linear polarization results.

Abstrak :
[ABSTRAK
Korosi memiliki dampak yang sangat besar terhadap ekonomi dan lingkungan pada berbagai infrastruktur, terkait dengan kegagalan operasi dan aset. Masalah yang umum terjadi pada jaringan pipa minyak dan gas saat ini adalah korosi internal yang disebabkan oleh media korosif yang umumnya mengandung karbon dioksida (CO2) dalam larutan aqueous. Karenanya, diperlukan cara untuk mengevaluasi korosi CO2 pada baja karbon terkait laju korosi agar dapat memenuhi umur operasi. Dalam penelitian ini, model Norsok yang telah dimodifikasi digunakan untuk memprediksi laju korosi pada lingkungan CO2, dan mempertimbangkan data parameter seperti suhu, tekanan parsial CO2, dan laju aliran untuk menghitung shear stress dan laju korosi. Software ini dibuat dengan menggunakan bahasa pemrograman visual basic (Microsoft Visual Studio ? VB), kemudian dengan menggabungkan basis pengetahuan mekanisme korosi CO2 dan aturan tertentu maka akan dihasilkan suatu sistem pakar. Berdasarkan perhitungan shear stress dan laju koros, kemudian rekomendasi dapat diajukan untuk mempertimbangkan, apakah baja karbon masih dapat digunakan atau penggunaan baja karbon dengan memberikan inhibitor atau penggantian baja karbon dengan Corrosion Resistance Alloys. Hasil perhitungan modifikasi model Norsok menunjukkan bahwa hasil perhitungan laju korosi tampak lebih realistis dibandingkan dengan model Norsok asli, dan dapat digunakan untuk mengevaluasi baja karbon yang mengalami korosi CO2 dengan tingkat kepercayaan lebih tinggi.

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ABSTRACT
Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident.;Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident., Corrosion has a great detrimental effect to economy and environment in almost all infrastructures, in regards of operations shutdown and asset facilities failure. A common problem in oil and gas process piping and transport pipeline nowadays is internal corrosion caused by corrosive media containing mainly carbon dioxide (CO2) in aqueous solutions. Therefore, there is a need to evaluate CO2 corrosion of carbon steel in terms of corrosion rate in order to meet its life expectancy in such environment. In this paper, a modified Norsok model was used to predict corrosion rate in CO2 environment, and consider typical data parameter used such as temperature, CO2 partial pressure, and flow rate or fluid velocity to calculate shear stress and corrosion rate. By combining knowledge base related to CO2 corrosion mechanism and its logic algorithm with certain rules resulted in such expert system which utilize visual basic (Microsoft Visual Studio-VB) programming language to develope a software. Based on calculated shear stress and corrosion rate, then recommendations can be proposed whether carbon steel still can be used or carbon steel with inhibitor injection or carbon steel replaced by Corrosion Resistance Alloys. The modified Norsok calculation model results show that the calculated corrosion rates are likely more realistic compared to the original Norsok model, and can be used to evaluate carbon steel which suffered CO2 corrosion with highly confident.]

Abstrak :
Kawat bronjong adalah kawat dengan struktur anyam yang terbuat dari baja galvanis. Penggunaan kawat bronjong sering diaplikasikan sebagai pondasi ataupun penahan anti korosi untuk mencegah bencana erosi, tanah longsor, dan abrasi. Adapun baja galvanis terdiri dari baja sebagai substrat yang dilindungi oleh lapisan pelindung seng. Akan tetapi performa lapisan seng dalam melindungi baja galvanis bergantung dari beberapa faktor, salah satunya kekasaran permukaan lapisan. Pada penelitian ini akan membahas pengaruh kekasaran permukaan lapisan seng terhadap ketahanan korosi. Variabel yang digunakan terdiri dari tiga sampel (BAL, BAI, dan BJ) dengan masingmasing bentuk heliks dan non-heliks Setiap sampel memiliki nilai kekasaran permukaan masing-masing yaitu BAL (2,185 μm); BAI (2,068 μm); dan BJ (2,775 μm). Proses ketahanan korosi menggunakan metode immersion test dengan larutan korosif HCl 1 M selama 21 hari. Hasil immersion test kemudian ditimbang dan dilakukan karakterisasi menggunakan mikroskop optik (OM) dan mikroskop elektron (SEM-EDS). Berdasarkan immersion test, sampel BJ dengan bentuk heliks menghasilkan laju korosi tertinggi. Kemudian kemampuan mekanis material sebelum dan setelah korosi mengalami perubahan dalam aspek kekerasan. Pengujian kekerasan menggunakan mesin microvickers dengan indentasi 25 gf dan waktu selama 10 detik. Berdasakan hasil kekerasan, didapatkan bahwa sampel BAI dengan kandungan seng tertinggi cenderung paling lunak. Di lain sisi, produk korosi yang terbentuk di permukaan tiap sampel menyebabkan material menjadi lebih keras dan brittle. ......Gabion wire is woven wire made of galvanized steel. It is often used as a foundation or corrosion-resistant barrier to prevent erosion, landslides, and abrasion. Galvanized steel consists of steel as the substrate protected by a zinc coating. However, the performance of the zinc coating in protecting the galvanized steel depends on several factors, one of which is the surface roughness of the coating. This study discusses the influence of zinc coating surface roughness on corrosion resistance. The variables used consist of three samples (BAL, BAI, and BJ) with each having both helical and non-helical forms. Each sample has a specific surface roughness: BAL (2.185 μm); BAI (2.068 μm); and BJ (2.775 μm). The corrosion resistance process uses the immersion test method with 1 M HCl corrosive solution for 21 days. The immersion test results were then weighed and characterized using Optical Microscopy (OM) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Based on the immersion test, sample BJ with a helical form showed the highest corrosion rate. Subsequently, the mechanical properties of the material before and after corrosion showed changes in hardness. The hardness test used a microvickers machine with a 25 gf indentation and a dwell time of 10 seconds. According to the hardness results, sample BAI, which had a highest zinc content, tended to be the softest. On the other hand, the corrosion products formed on the surface of each sample made the material harder and more brittle.

Abstrak :
Bahan baku baja selama ini kebanyakan berasal dari bijih besi hematit. Tidak adanya bahan baku bijih besi ini di Indonesia mendorong perusahaan besi baja untuk membuat baja dari mineral laterit yang tersebar di Indonesia dengan kandungan Fe cukup tinggi sekitar 50%. Baja laterit masih diproduksi terbatas dan belum banyak diaplikasikan. Salah satu contoh aplikasi baja laterit adalah sebagai material jembatan TEKSAS diatas Danau Mahoni, Universitas Indonesia. Karena terpapar secara langsung pada lingkungan, maka ketahanan korosi baja laterit perlu diketahui. Pada kondisi aplikasi ini baja laterit mungkin terbasahi air danau, dan faktor lingkungan seperti temperatur dapat mempengaruhi ketahanan korosi baja laterit. Penelitian ini bertujuan untuk mengetahui pengaruh temperatur terhadap laju korosi baja karbon dari bijih besi hematit dan baja laterit pada lingkungan air danau FTUI. Perbedaan mendasar baja laterit dan baja karbon adalah adanya elemen tambahan Ni dan Cr pada baja laterit yang menggolongkan baja laterit sebagai baja paduan rendah (low alloy steel) dan dapat mempengaruhi ketahan korosi dari baja. Pengujian laju korosi menggunakan metode weight loss dimana kedua jenis baja direndam dalam air danau selama 1, 2, 3, 4 dan 5 hari dengan 3 variasi temperatur, yaitu temperatur ruang, 50°C dan 70°C. Dalam penelitian ini disimpulkan laju korosi baja karbon cenderung menurun 13% dan baja laterit cenderung konstan seiring dengan bertambahnya waktu pada temperatur ruang dan cenderung menurun sekitar 12% pada baja karbon dan 17% pada baja laterit dengan bertambahnya waktu pada temperatur 50°C dan pada 70°C laju korosi cenderung menurun 9% untuk baja karbon dan 20% untuk baja laterit. Laju korosi baja karbon dan baja laterit meningkat dengan bertambahnya temperatur. Pada baja karbon laju korosi meningkat dari 4,4 mpy pada temperature ruang menjadi 10,3 mpy pada temperatur 50°C dan 11,5 mpy pada temperature 70°C. Pada baja laterit laju korosi juga meningkat dari 3,58 mpy pada temperature ruang menjadi 9,09 mpy pada temperatur 50°C dan meningkat lagi menjadi 11,5 mpy pada temperatur 70°C. Laju korosi baja laterit mempunyai ketahanan korosi yang lebih baik dari baja karbon karena pengaruh elemen paduan yang terkandung dalam baja laterit. ......Most of steel are produced from hematite iron ore. The scarcity of hematite iron ore in Indonesia, encouraged iron & steel company to produced steel from laterite mineral, which has high deposit in Indonesia with high grade iron (50%Fe). Laterite steel now are produced with limited quantity. One of the application of laterite steel as material in TEKSAS bridge on Mahoni lake, University of Indonesia. Because laterite steel directly exposed to environment, corrosion resistance of laterite steel is an important factor. Laterite steel bridge may wetting with lake water and environment factor, like temperature could effect laterite steel corrosion resistant. The objective of this research to observe the influence of temperature to corrosion rate of carbon steel from hematite iron ore and laterite steel on lake water environment. The difference between carbon steel and laterite steel, are addition of Cr and Ni on laterite steel, which classified laterite steel into low alloy steel and may effected corrosion behaviour of steel. Corrosion rate measurement are conducted by weight loss method, which both of steel immersed in lake water with time period 1, 2, 3, 4 and 5 day at room temperature, 50°C and 70°C. The conclusion of this research was the corrosion rate of carbon steel decreased 13% and laterite steel were constant with immersion time at room temperature. But, tendency of carbon steel and laterite steel corrosion rate decreased with immersion time in temperature 50°C and 70°C. Carbon steel decrease about 12% and laterite steel 17% in temperature 50°C. Corrosion rate of carbon steel in temperature 70°C decrease 9% and laterite steel 20%. The corrosion rate of carbon steel and laterit steel increased with increasing temperature. Corrosion rate of carbon steel increase from 4,4 mpy in room temperature into 10,3 mpy in temperature 50°C and 11,5 mpy in temperature 70°C. Corrosion rate of laterite steel increase from 3,58 mpy at room temperature to 9,09 mpy at temperature 50°C and to 11,5 mpy at temperature 70°C. Laterite steel have higher corrosion resitance than carbon steel because of addition element on laterite steel.

Abstrak :
Perilaku inhibisi ekstrak ubi ungu berdasarkan pengaruh waktu rendam yang ditambahkan (2 ml pada setiap wadah) pada baja karbon rendah di lingkungan air demineralisasi yang diinjeksikan karbon dioksida telah diteliti dengan menggunakan metode kehilangan berat. Ekstrak ubi ungu dipilih sebagai green corrosion inhibitor karena mengandung senyawa antioksidan yang dapat menghambat laju korosi. Waktu perendaman sampel baja SPCC adalah 3, 6, 9, 12 hari. Hasil penelitian menunjukkan ekstrak ubi ungu dapat menurunkan laju korosi baja karbon rendah di lingkungan air demineralisasi yang dinjeksikan karbon dioksida dengan efisiensi sebesar 9.1576 - 24.8356 % dengan penambahan konsentrasi 2 di setiap wadahnya. ......Behavioral inhibition of purple sweet potato extract based on the effect of exposure time (2 ml every container) on low carbon steel sample in Carbon dioxide (CO2) Injected Demineralized Water environment has been investigated using weight loss method. 'ekstrak ubi ungu' is selected as green corrosion inhibitors because they contain antioxidant compounds that can inhibit the corrosion rate. The time of immersion for SPCC steel sample are 3, 6, 9, and 12 days. Results showed 'ekstrak ubi ungu' can decrease the corrosion rate in Carbon dioxide (CO2) Injected Demineralized Water environment with an efficiency of 9.1576 - 24.8356 % with the addition of 2 ml concentration every container.