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Journal : Semesta Teknika

Karakterisasi Sambungan Friction Stir Spot Welding pada Plat Aluminium 5083 Aris Widyo Nugroho; Fajar Hari Purnomo; Muhammad Budi Nur Rahman
Semesta Teknika Vol 24, No 1 (2021): MEI 2021
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v24i1.12603

Abstract

Karakterisasi sambungan las titik aduk pelat Alumunium 5083 telah dilakukan untuk mengetahui pengaruh waktu diam dan putaran pahat terhadap sambungan. Plat Aluminium 5083 dipotong menjadi benda uji dengan dimensi 100 x 30 x 3 mm. Sambungan putaran diterapkan untuk mengelas spesimen sesuai dengan standar AWS D8.9-97. Alat dengan diameter bahu 20 mm dan pin tirus disiapkan. Proses Friction strir welding (FSSW) dilakukan dengan menggunakan parameter dwell-time 5, 10 dan 15 s dengan kecepatan putar masing-masing 1500 dan 2280 rpm. Temperatur pelat di dekat pin selama proses pengelasan diukur menggunakan termokopel tipe K. Morfologi dan struktur mikro sendi diamati menggunakan mikroskop optik. Kekerasan dan kapasitas beban tarik dari sambungan juga dievaluasi. Hasil penelitian menunjukkan bahwa parameter kecepatan rotasi dominan mempengaruhi kualitas sambungan. Daya dukung tarik yang lebih tinggi ditemukan pada kecepatan putar yang lebih tinggi pada setiap dwell-time yang mencapai maksimum 3105,4 N. Semua spesimen menunjukkan kegagalan pull out nugget akibat terjadinya beban geser yang mendominasi penyebab kegagalan.
Mikrostruktur dan Kekerasan Sambungan Pengelasan Gesek Disimilar Pipa Tembaga/Kuningan (Cu/Cu-Zn) Aris Widyo Nugroho; Totok Suwanda; Septian Aldo Serena
Semesta Teknika Vol 19, No 1 (2016): MEI 2016
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v19i1.2047

Abstract

This study is focused on the influence of friction time on the microstructure and the hardness values of butt  welded dissimilar pure copper/brass alloy pipes by continuous drive friction  welding. Five variation of friction times were applied during the welding processes. The joint were evaluated by microstructural analysis  and microhardness measurements. The results show that three distincs region were observed.  The grain formation in the three regions were revealed.  It was found that the hardness of the joints especially in HAZ regions were lower than that of the copper and brass base metals, while the hardness of the TMAZ region was higher than that of the copper base metal and the brass base metal. The microhardness values in the TMAZ  increased  with increasing the friction time up to 30 s and then decreased with incresing friction time.
Analisa Kegagalan Sambungan Las Pada Tiang Penyangga Dermaga Koko Nusyi Syahputra; Aris Widyo Nugroho
Semesta Teknika Vol 18, No 1 (2015): MEI 2015
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v18i1.700

Abstract

Welded join failure analysis of broken jetty head strut has been carried out to find out the root cause of the failure which was obverved at the ring welding. Specimens being made of unbroken and broken struts were characterized and analyzed. The results show that the chemical composition of the based metal and the strut welded  joins especially their phosporus content were close to that of the ASTM A 252 grade 2 standard.   A common phenomenon was noted on the hardness testing result where the hardness numbers of the weld metal zone were found being higher than those of the base metal. The Widmanstatens stucture was noticed on both the weld metal and the coarse grain zone.  Further examination of the macrostructures revealed that blow holes and incomplete fusions were detected on the weld metal of the broken struts.  These flaws may the root cause of the failure because they acted as an initial crack that may propagate until fracture.
Sifat Mekanis dan Struktur Mikro Pengelasan Gesek Baja Tahan Karat Austenitik AISI 304 Aris Widyo Nugroho, Totok Suwanda, Febri Irwanto
Semesta Teknika Vol 17, No 1 (2014): MEI 2014
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v17i1.413

Abstract

The aim of this study is to investigate experimentally the microstructural properties and welding strengths of the friction welded joints using austenitic stainless steel (AISI 304) base metal. The experiments were carried out using a beforehand designed and constructed experimental friction welding set-up. Firstly, the welding experiments were under different friction pressure (1,38-4,14 MPa) and upsetting pressure (6,90-8,27 MPa). Later, the strengths of the joints were examined by tension test and the results were compared with those of the base metals. Microstructures in the interfaces of the joints were also obtained and examined. The results show that porosities were observed in bondline zone for all specimens. As the friction pressure increased, the fully plastically deformed zone becomes increased.  Tensile test results indicated that, generally the joint strength is increased with an increase of the friction pressure and the upsetting pressure. The friction welded joint strenght were found to be lower than that of the base metal. The detailed fractographic observation confirmed that the brittle rupture occurred at the joint zone. 
Pembuatan Aluminium Berpori dengan metode Metalurgi Serbuk Berbahan Amonium Hidrogen Karbonat ((NH4)HCO3) sebagai Space Holder beserta Karakterisasinya Aris Widyo Nugroho; Iswanto Iswanto
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.212220

Abstract

The reseacrh on fabrication of porous aluminum using powder metallurgy technique with amonium hidrogen karbonat as space holder has been carried out. The space holder powder with various space holder mass fraction of 20%,30%, 40% and 50% in 5 gram of total mass and the aluminum powder were put into a can for mixing process. Afterward the mixed powder was compacted at 300 kg/cm2 to obtain the green body. Density of the green body was then determined by measuring its dimension and the mass. Following this, the green body was put in a furnace and heated up to 200oC with holding time of 60 minutes for space holder removal. The second heating up was carried out up to 650oC with holding time of 60 minutes for sintering process and the furnace was then switched off for cooling. Porosity of the sintered porous aluminum was calculated and its microstructure was examined using an optical microscop. The compressive strength of the porous material was evaluated using universal testing machine. The result show that the porosity increases with an increase of the mass fraction in the range of 56-74% with the compressive strength in opposite way. The strength was found in the range of 1.2-15.7 MPa. All specimens show a typical britlle materials.
Pengaruh Sudut Kampuh V Tunggal terhadap Sifat Mekanis Sambungan Las SMAW pada Pipa Baja Karbon API 5L X46 Aris Widyo Nugroho; Sigit Hartanto; Muhammad Arinalhaq Eko Nugroho; Rela Adi Himarosa
Semesta Teknika Vol 25, No 2 (2022): NOVEMBER 2022
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.v25i2.16896

Abstract

Penelitian untuk mengetahui pengaruh sudut kampuh V pengelasan SMAW terhadap sifat mekanis sambungan las pada material pipa API 5L X46 telah dilakukan. Proses pengelasan dilakukan dengan sambungan butt-joint kampuh V tunggal menggunakan material pipa API 1104 5L grade X46 dengan tebal pipa 12,7 mm. Sudut kampuh yang digunakan adalah 45º, 50º, 55º, 60º, 65º, 70º, dan 75º. Sambungan lasan kemudian dilakukan beberapa pengujian meliputi inspeksi visual, uji NDT RI, uji metalografi menggunakan standar ASTM E340-15, uji kekerasan menggunakan standar ASTM E92-82, dan uji bending menggunakan standar API 1104. Hasil penelitian menunjukkan bahwa semakin besar sudut kampuh las maka heat input dan waktu proses semakin besar. Secara umum kekerasan HAZ dan WM meningkat seiring dengan peningkatan sudut kampuh. Nilai kekerasan sebesar 135,73 VHN pada HAZ, dan 146,19 VHN pada WM diperoleh pada sudut kampuh 75o. Tegangan bending maksimum pada root bend dan side bend test meningkat seiring dengan kenaikan sudut kampuh dan berturut-turut tercapai pada variasi sudut kampuh 60º sebesar 5.685 MPa dan 4.222 MPa, kemudian tegangan lentur menurun bila sudut kampuh membesar. Sudut kampuh 60o merupakan sudut kampuh optimal dari segi sifat mekanis sambungan dan produktifitas proses pengelasan.