Analisis Kerusakan Rel Kereta Api Angkutan Batubara

Apriardi Ihlas


The use of thermite welding technology on railway connection is the primary option due to its mobility and cost. There are many failures on railway used to transport large amount of coal. This study performed a series of examinations and tests to find the main cause of broken railway connections. Macro fractographic test showed chevron fracture pattern and ratchet mark as indication of crack initiation area, which was the centerline of welding area. Metallographic examination on crack initiation areas showed weak ferrite phase network with large perlite grains. It was also found a number of micro porosity which supported the result of fractographic examination. Micro fractographic examination by Scanning Electron Microscope (SEM) showed a typical brittle fracture and a lot of micro porosity. Chemical composition examination by Energy Dispersive Spectrometer (EDS) showed an alumina inclusion slag. Therefore, low quality of thermite welding connection was caused by initial crack from the inside in the form of micro porosity in the centerline of welding area.

Penggunaan teknologi pengelasan termit pada sambungan rel kereta api menjadi pilihan utama karena mobilitas dan biayanya. Kerusakan telah terjadi pada sambungan rel kereta api yang digunakan sebagai angkutan batu bara dalam jumlah yang banyak. Pada penelitian ini akan dilakukan serangkaian pemeriksaan dan pengujian untuk mencari penyebab utama patahnya sambungan rel tersebut. Berdasarkan pemeriksaan fraktografi secara makro memperlihatkan pola patahan chevron dan ratchet mark sebagai petunjuk daerah awal retakan, yaitu centerline daerah las. Hasil pemeriksaan metalografi pada daerah inisiasi retakan menunjukkan terbentuknya jaringan fasa ferit yang lemah dengan ukuran butir perlit yang besar. Selain itu ditemukan sejumlah porositas mikro yang mendukung hasil pemeriksaan fraktografi. Hasil pemeriksaan fraktografi secara mikro dengan Scanning Electron Microscope (SEM) memperlihatkan tipikal patahan getas dan ditemukan  banyak porositas mikro. Dari pemeriksaan komposisi kimia dengan Energy Dispersive Spectrometer (EDS) ditemukan slag inklusi tipe alumina. Dengan demikian, rendahnya kualitas sambungan las termit diakibatkan oleh terbentuknya retakan awal dari dalam berupa porositas mikro pada centerline daerah las.


rel kereta api, las termit, porositas penyusutan interdendritik, jaringan ferit, slag inklusi alumina

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