Pengaruh Underwater Welding Terhadap Perubahan Sifat Mekanik Weld Joint Material Baja Di Lingkungan Laut

Hudaya, Ervan Harya (2008) Pengaruh Underwater Welding Terhadap Perubahan Sifat Mekanik Weld Joint Material Baja Di Lingkungan Laut. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Struktur lepas pantai lambat laun akan mengalami kerusakan. Berbagai metode reparasi bangunan lepas pantai akan membutuhkan reparasi bawah air. Oleh karena itu, pekerjaan las bawah air menjadi hal yang sangat penting. Melalui penelitian ini, dikaji perubahan sifat mekanik pada sambungan las material baja lunak yang di las di lingkungan laut. Dengan parameter las yang sama, juga dilakukan pengelasan di air tawar dan di darat sebagai pembanding. Pekerjaan las bawah air dilakukan dengan metode SMAW wet welding pada posisi 1G (datar) dengan elektroda AWS E-6013 yang dilapisi dengan lilin yang bersifat kedap air. Melalui pengamatan metalografi struktur makro, pada pengelasan bawah air banyak terlihat adanya hydrogen embrittlement akibat proses disosiasi air selama proses pengelasan. Pada pengamatan struktur mikronya, tampak bahwa fase martensit hasil pengelasan di lingkungan laut lebih banyak daripada hasil las di air tawar dan di darat. Nilai kekerasan material yang dilas di lingkungan laut lebih besar dibanding kekerasan material yang di las di air tawar dan di darat, yaitu sebesar 195,37 (Hv10) > 181,13 (Hvl0) > 153,96 (Hv10). Nilai kekuatan tarik hasil pengelasan di lingkungan laut juga sedikit lebih tinggi dibandingkan dengan kekuatan tarik hasil lasan di air tawar dan di darat, berturut turut sebesar 49,44 Kgf/mm>49,41 Kgf/mm2>48,99 Kgf/mm2. Akan tetapi,elongasi dan reduksi penampangnya lebih rendah dibandingkan yang lainnya. Semua hal ini menandakan bahwa material baja yang dilas di lingkungan laut sifat mekaniknya bersifat lebih getas daripada material yang di las di air tawar dan darat.
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Offshore structures will be getting damaged gradually. A number of methods for offshore structure's reparation needs underwater repairs. Thus, underwater welding will become an essential part. By conducting this, mechanical properties changes of weld joint's steel material welded in marine environmental were observed. By using similar welding parameter, material also welded in fresh water and air due to comparison. Underwater welding method used in this research is SMAW wet welding in 1 G (flat position) with A WS electrode type 6013 coated with wax. Through macrostructure metallography examination in underwater welding, it was found that there are many of hydrogen embrittlement due to water disassociation during welding process. Through microstructure metallography examination, it was found that martensite phase in specimen welded in marine environmental are more appeared than specimen welded in fresh water and air. Hardness of specimen welded in marine environtmental was also greater than in fresh water and air, with comparison of value 195,37 (Hv10)> 181,3 (Hv10)> 153,96 (Hv10). Tensile strength of weld joint material welded in marine environment also greater than in fresh water and air with value 49,44 Kgf/mm2:>49,41 Kgf!mm2:>48,99 Kgf/mm2.Otherwise, reduction of area and elongation value of material welded in marine environmental are lower than in fresh water and air. It proves mechanical properties of steel material welded in marine environtmental is more brittle than in fresh water and air.

Item Type:	Thesis (Other)
Additional Information:	RSKe 671.52 Hud p-1 2008
Uncontrolled Keywords:	las bawah air, sambungan las, sifat mekanik, struktur mikro, underwater welding, weld joint, mechanical properties, microstructure.
Subjects:	T Technology > TN Mining engineering. Metallurgy > TN879.6 Welding T Technology > TS Manufactures > TS227 Welding.
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Totok Setiawan
Date Deposited:	04 Jul 2023 07:47
Last Modified:	04 Jul 2023 07:47
URI:	http://repository.its.ac.id/id/eprint/98269

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