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All Journal UNEJ e-Proceeding Prosiding Seminar Nasional Rekayasa Teknologi Industri dan Informasi ReTII
Joko Pitoyo
STTNAS Yogyakarta
Aerospace Engineering Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Transportation

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MICROSTRUCTURE AND MECHANICAL PROPERTIES OF DISSIMILAR JOINT OF COLD ROLLED STEEL SHEETS 1.8 SPCC-SD AND NUT WELD M6 BY SPOT WELDING Ratna Kartikasari; Mustakim Mustakim; Joko Pitoyo; Feri Frandika
UNEJ e-Proceeding 2016: Proceeding The 1st International Basic Science Conference
Publisher : UPT Penerbitan Universitas Jember

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Resistance spot welding is one of welding methods which is most widely used especially in the medical equipment industry. Unfortunately, interfacial fracture and pullout fracture often occur. The aim of this research is to find optimum current and time of resistance spot welding process for the best micro structure and mechanical properties. This research combined two spot welding parameters of cold rolled steel sheets1.8 SPCC-SD and nut weld M6: current (49, 52, 55, 58, 61 Ampere) and time (14, 17, 20, 23, 26 cycle). Optical microscopic, Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were used to examine weld zone, heat affected zone (HAZ) and parent metal microstructure. The mechanical properties were investigated using universal tensile test and Vickers micro hardness. It was found that the lowest current and cycle result incomplete joining, while the higher current and cycle increase tensile strength and hardness. The micro structures tend to be ferritic with acicular, grain boundary and widmanstaten ferrite on the weld zone for all parameters. The best microstructure and mechanical properties occur at 14 cycle and 61 A of parameters combination.
Upaya Peningkatan Kekerasan Grinding Ball Besi Tuang Putih Astm A532 Dengan Proses Temper Mus ta kim; Joko Pitoyo; Ratna Kartikasari
Retii Prosiding Seminar Nasional ReTII ke-12 2017
Publisher : Institut Teknologi Nasional Yogyakarta

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Hingga saat ini kebutuhan besi tuang putih ASTM A 532 untuk grinding ball pada industri semen masih dipenuhi dengan impor. Percobaan pembuatan paduan ini sudah dilakukan pada skala IKM. Akan tetapi satu kekurangan paduan yang dihasilkan bersifat getas sehingga nilaiketangguhan relatif rendah. Penelitian ini bertujuan untuk mempelajari upaya peningkatan kekerasan dan ketangguhan besi tuang putih ASTM A 532 produk IKM untuk aplikasi grinding ball pada industri semen dengan proses temper. Hasil pengujian komposisi kimia menunjukkan bahwa besi tuang putih ASTM A532 mengandung 4,57% C, 18,26% Cr dan 0,20 % Mo sehingga termasuk dalam ASTM A532 class II type D martensitic white cast iron. Hasil uji struktur mikro menggunakan mikroskop optik dan SEM menunjukkan bahwa besi tuang putih ASTM A532 mempunyai struktur martensit, perlit dan sementit, tetapi memiliki pola, jumlah dansebaran yang berbeda. Hasil pengujian kekerasan menunjukkan bahwa besi tuang putih ASTM A532 mempunyai nilai kekerasan tertinggi yaitu pada besi tuang putih ASTM A532 spesimen setelah hardening 900ºC yaitu sebesar 878,59 kg/mm2 dan terendah 744,80 kg/mm2 pada specimen temper 450 0C. Hasil pengujian XRD menunjukkan persentase (%) terbesar struktur mikro adalah sementit, selanjutnya adalah martensite dan perlit. Semakin tinggi temperatur temper nilai kekerasan besi tuang putih ASTM A532 menurun tapi keuletannya akan naik, hal inidisebabkan terjadinya perubahan strukturmikro dari martensit menjadi martensit temper.Kata kunci: Besi tuang putih ASTM A 532, martensitik, kekerasan, impak, temper
Co-Authors Feri Frandika Mus ta kim Mustakim Mustakim Ratna Kartikasari