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VARIASI ARUS LISTRIK TERHADAP SIFAT MEKANIK MIKRO SAMBUNGAN LAS BAJA TAHAN KARAT AISI 304 Yakub, Yunus; Nofri, Media
E-journal Widya Eksakta Vol 1, No 1 (2013)
Publisher : E-journal Widya Eksakta

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Abstrak:Â Â Dasar penelitian ini adalah karena baja tahan karat merupakan baja paduan tinggi, maka kualitas sambungan lasnya sangat dipengaruhi dan menjadi getas oleh panas dan atmosfer pengelasan. Dalam penelitian ini dilakukan pengelasan baja tahan karat AISI 304 sebagai material logam utama. Baja tahan karat AISI 304 merupakan baja paduan tinggi yang memiliki kandungan 0,08% C, < 2,00% Mn, < 1,00% Si, 18,00-20,00% Cr dan 8,00-12,00% Ni. Baja tahan karat mempunyai sifat yang berbeda dengan baja karbon maupun dengan baja paduan rendah, hal ini yang sangat mempengaruhi sifat mampu lasnya. Penelitian ini bertujuan untuk menganalisa pengaruh dari variasi arus pengelasanÂ terhadap uji metallografi, uji kekerasan dan uji tarik pada sambungan las baja tahan karat AISI 304. Pengelasan dengan las GTAW dengan variasi kuat arus 30A, 40A dan 50A. Hasil penelitian ini menunjukkan nilai kekerasan Vickers tertinggi terdapat pada penggunaan kuat arus 40A (benda uji II) yaitu sebesar 226 kg/mm2, kekuatan tarik maksimum terjadi pada benda uji II (40A) sebesar 698Â N/mm2 . Hal ini disebabkan karena struktur mikro daerah HAZ pada benda uji II (40A) berupa austenit yang paling sedikit ditemukannya endapan karbid Krom dibandingkan dengan struktur mikro dari daerah HAZ benda uji I (30A) dan benda uji III (50A).Kata kunci: struktur mikro daerah HAZ , baja tahan karat.Abstract:Â Â The research underlies on the fact that stainless steel is a high alloy steel; the welding connection quality is strongly influenced and become brittle by welding heat and atmosphere. In this research, the welding of stainless steel AISI 304 would be conducted as the primary metal material. AISI 304 stainless steel is a high alloy steel which contains 0.08% C, < 2.00%, Mn, < 1.00% Si, 18.00 to 20.00% Cr and 8.00 to 12.00% Ni. Stainless steel has different properties with carbon steel and low alloy steel with; this can greatly affect the nature of welding. This research aims to analyze the influence of variations in the welding current to metallographic test, hardness test and tensile test on welded joints of stainless steel AISI 304. Welding with GTAW welding with strong variations in the flow of 30A, 40A and 50A. The results of this study showed the highest Vickers hardness values are strong currents on the use of 40A (specimen II) that is equal to 226 kg/mm2, the maximum tensile strength occurs in the test specimen II (40A) of 698 N/mm2. This is because the microstructure of the HAZ in the test specimen II (40A) of austenite the least discovery of chromium carbide precipitation compared to the microstructure of the HAZ specimen I (30A) and III specimens (50A).Â Key words: microstructure of the HAZ, stainless steel

ANALISIS SIFAT MEKANIK PIPA CARBON STEEL GRADE A A106 DAN GRADE B A53 UNTUK PROSES PRODUKSI PADA KILANG LNG Nofri, Media; Fardiansyah, Arif
Bina Teknika Vol 14, No 2 (2018): Bina Teknika
Publisher : Fakultas Teknik UPN "Veteran" Jakarta

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This study aims to determine the quality and mechanical properties of carbon steel pipes for the production process at a good liquefied Liquified Natural Gas and after 10 years of use. As a temporary repair reference on damaged pipe. The step is to compare the results of testing the mechanical properties and microstructure of both types of pipes. The parameters used are chemical composition, hardness, tensile strength, and micro structure of both types of pipes. Test results on a good pipe have an average hardness value of 90 HV whereas in the damaged pipe the average hardness value of 85.9 HV decreased by 4.1 HV. The tensile test on a good pipe value of 60kg / mm2 (588 MPa), on a damaged tube of tensile strength of 56 kg / mm2 (549 MPa), decreased 4 kg / mm2 (39 MPa). Good pipe microstructure test results consist of ferrite and pearlite structures while in the damaged pipe consisting of pearlite phase. From the results of the study concluded that the pipeline after the use for 10 years experienced a decrease in mechanical properties, namely: hardness and tensile strength. This is the result of thinning of the corrosion pipe wall thickness.

PERUBAHAN SIFAT MEKANIS DAN STRUKTUR MIKRO BAJA JIS G4051 S15C AKIBAT HARDENING DENGAN VARIASI MEDIA PENDINGIN Nofri, Media
Bina Teknika Vol 13, No 1 (2017): Bina Teknika
Publisher : Fakultas Teknik UPN "Veteran" Jakarta

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Testing is an experiment to know the change of mechanical properties and micro structure in JIS G 4051 S 15 C series steel which is previously was cooled with some variation of media such as immersion into water, oil and cooling in free air then the test include: chemical composition, hardness , Impact, Fractography and Metallography. From result of testing the chemical composition with main integer element got result: 0.15% C, 0.157% Si, 1.2% Mn, 0.01% P, 0.02% S. Hardness test results with Vickers method obtained 183 HV for original test object (original) , 182.66 HV for water-cooled test specimens, 190.33 HV cooled with oil and 196.33 HV cooled with air. While in the impact test the toughness value is 0.5 Joule / mm2 for the original test object, 0.39 Joule / mm2 water-cooled test specimens, 0.56 Joule / mm2 oil-cooled specimen, and 0.61 Joule / mm2 cooled test object With free air. In Fractography testing can not be further analyzed the type of fracture, because the photo does not showed the form of cracks or fault plot. While the metallographic results for the original test object or non heat treatment structure is Ferrite and Pearlit, after Hardening the structured remains Ferrit and Pearlit, there is a change in the structure form into Martensit. The mechanical properties generated after the testing process on the JIS G 4051 S 15 C steel have increased the toughness and decreased the hardness so that the steel can be summarize to be more resilient than the original.

PERUBAHAN SIFAT MEKANIK BAJA KONSTRUKSI JIS G4051 S17C SETELAH DILAKUKAN HARDENING DAN TEMPERING Nofri, Media
Bina Teknika Vol 11, No 2 (2015): Bina Teknika
Publisher : Fakultas Teknik UPN "Veteran" Jakarta

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Material JIS G 4051 S 17 C including low carbon steel with alloy composition 0:15% C, 0.157% Si, 1.2% Mn, 0.01% P, of 0.02% S. Low carbon steels are widely applied for construction machinery. This study aimed to analyze the effects of the process of hardening and tempering on material hardness, impack and metallografi. Results of this research show the value of Brinell hardness will increase the hardening process with temperatures of 900 C, holding time 15 minutes and the coolant medium is water. Brinell hardness is HB 364.22, is due to the structure of ferrite and pearlite transformed to martensite. Impack results increased in the process of tempering with temperature 500 C, holding time 15 minutes are cooled with air. Impack toughness value of 0.447 Joule / mm2, is because the value of tenacity to grow up and hardness decreased in the coarse grain structure.

ANALISIS SIFAT MEKANIK BAJA SKD 61 DENGAN BAJA ST 41 DILAKUKAN HARDENING DENGAN VARIASI TEMPERATUR Nofri, Media; Taryana, Acang
Bina Teknika Vol 13, No 2 (2017): Bina Teknika
Publisher : Fakultas Teknik UPN "Veteran" Jakarta

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The alloy steel that is widely used in the world of manufacturing industry is the type of tool steel because it has special characteristics and includes special steel. One type of tool steel that is widely used by the manufacturing industry is SKD steel type 61. ST 41 steel material is a low carbon steel with a carbon content of 0.08% -0.20%. ST 41 steel is commonly used as industrial machine component, but in this ST 41 steel is not as strong as steel SKD 61. So, to improve quality to ST 41 steel. Quality improvement can be done by heat treatment process. To obtain hardness requires the heating process, holding time, cooling medium, precise hardening temperature and see the material comparison between SKD 61 steel and ST 41 steel before and after the hardening process to the nature of hardness and microstructure. Result of hardness test of SKD 61 nonheattreatment steel material has hardness value equal to 197 HV, ST 41 nonheatreatment steel material has hardness value equal to 165 HV, after hardening for temperature 900⁰C has hardness value 154 HV, temperature 950⁰C has hardness value 152 HV, temperature 1000⁰C has 161 HV magnification value. Seen in the metallographic results appear to be a change in microstructure on ST 41 steel which after the hardening structure looks more dominant after the hardening structure turned into bainite-ferrit

PERBANDINGAN NILAI KEKERASAN DAN STRUKTUR MIKRO MATERIAL PISTON SEPEDA MOTOR 4 TAK ORIGINAL DAN IMITASI Nofri, Media
Bina Teknika Vol 15 No 2 (2019): Bina Teknika
Publisher : Faculty of Engineering UPN "Veteran" Jakarta

The function of the piston is to accept the pressure from the combustion of the gas mixture and continue the pressure to pass through the connecting rod. The use of aluminum as a piston material is inseparable from its properties and is very suitable for pistons. n this study three piston materials were tested, namely piston A (Original), B (Imitation 1) and C (Imitation 2) with Aluminum material which also contained Silicon (AlSi). The tests carried out included testing the chemical composition, microstructure photographed from various position and hardness by the Vickers method. The results of these tests obtained varying hardness values with an average piston A value of 129 HV, piston B an average of 148.2 HV, piston C an average of 135.2 HV. The results of the microstructure test on piston C have srinkage casting defects and porosity defects while piston A and B have no defects. Whereas in testing the chemical composition of the value contained in the piston piston A has Al 81.7% and Si 14.0%, piston B Al 82.2% and Si 14.3%, piston C Al 83.5% and The 13.2%. From the results of the chemical composition test, the hardness value and microstructure of the three materials can be said to have almost the same value

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