PERBEDAAN SIFAT MEKANIK DAN SIFAT FISIK BAJA KARBON RENDAH YANG DILAS DENGAN BUTT JOINT DAN LAP JOINT MENGGUNAKAN SMAW

ABDURRAHMAN, ABDURRAHMAN and Pratiwi, Diah Kusuma (2016) PERBEDAAN SIFAT MEKANIK DAN SIFAT FISIK BAJA KARBON RENDAH YANG DILAS DENGAN BUTT JOINT DAN LAP JOINT MENGGUNAKAN SMAW. Undergraduate thesis, Sriwijaya university.

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Abstract

Low carbon Steel is a metal that has many advantages, such as lightweight, malleable, itfs cheap and has a good weldability. Low carbon Steel can be welded with all practical welding methods that exist and it will have good results if the preparation is perfect and the conditions are fulfilled. In general, defects in welding are common in low-carbon Steel, usually the defects occur because the welding current is too high which causes the Steel plate to yield or bend. In addition to yielding, welding defects that often occur is caused by a poor weld penetration. If the weld penetration is not good, it will result to a less sturdy construction. The reasons for that are because the welding speed is too high, the electric current is too low, and dirty work object The objective of this research is to compare physical and mechanical properties of SMAW welding using butt joint and lap joint methods. Welding is done on a low carbon Steel plate using a V seam with 1G position for butt joint, and double fillet for lap joint Both using the same welding current of 110 A. Then a couple of testing is performed, dye penetrant, visual, composition, hardness, tensile test, bending test, scanning electron microscopy (SEM) and Metallography test Dye penetrant test result shows that the lap joint welding has defects in the form Spatter while there are no defects in the butt joint This happens because the lap joint welding uses a high electric current and it is fillet shaped. While the visual ultrasonic test shows that there are defects in butt joint welding but there is no defect in the lap joint welding, this is because the butt joint welding is more difficult than lap joint welding. For butt joint welding, it uses a seam which consists of rootpass and weld out so that the penetration speed has to be exact. In hardness test, lap joint welding has the average of 88 HRB hardness on its welded area, while the butt joint welding has the average of 85 HRB hardness on its welded area. Tensile test is conducted which generate the breaking location contained in the base metal regions on both joint methods. Butt joint welding has a tensile strength by an average of 30.836 kgf/mm2, while lap joint welding has a tensile strength by an average of 26.936 kgf/mm2. This is because the hardness from the base metal in the lap joint is lower than the hardness on the base metal of the butt joint Due to the breaking location in the tensile test is in the region of the base metal, then we would like to know how the load and the maximum tensile stress in the welding area in both connections is, so we can use hardness and tensile stress relation table, so that from the table we can see the value of tensile stress of butt joint is 56.95 kgf/mm2 and tensile stress of lap joint is 60.46 kgf/mm2 * For bending test, lap joint welding has the bending strength with an average of 63.45 kgf/mm2. While the bending strength of butt joint has the average of 59.03 kgf/mm2. For Metallography test it shows that the microstructure of lap joint welding is more tough than the microstructure of butt joint welding, because the microstructure of lap joint composed of ferrite Widmanstatten, grain boundaiy ferrite, perlite and ferrite acicular which dominates, while microstructure of butt joint is composed of ferrite Widmanstatten , grain boundary ferrite, pearlite and ferrite acicular fewer than the number of acicular ferrite in the lap joint. In SEM test that has been done, only the butt joint welding area that can be tested by SEM methods, because the lap joint welding area is not severed, it can not be tested by SEM methods. Keywords: Low Carbon Steel, SMAW, Butt Joint, Lap Joint, Die Penetrant Test, Ultrasonic Test, Hardness Test, Tensile Test, Bending Test, Metalloghrafi, SEM Citations: 18., (1998-2015).

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	Baja Karbon Rendah, SMAW, Butt Joint, Lap Joint, Uji Die Penetrant Uji Visual Ultrasonik, Uji Kekerasan, Uji Tarik, Uji Lengkung, Metalografi, Uji SEM
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ1-1570 Mechanical engineering and machinery
Divisions:	03-Faculty of Engineering > 21201-Mechanical Engineering (S1)
Depositing User:	Ichlasyah Aisyah
Date Deposited:	08 Sep 2025 03:29
Last Modified:	08 Sep 2025 03:29
URI:	http://repository.unsri.ac.id/id/eprint/183693

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