The base metal used in this study was high strength low alloy (HSLA) AH-36 steel. The welding process used the E6013 as a rutile electrode. Four rutile electrodes were produced by adding Mg metal powder, ranging from 0 to 5 wt.%, to the initial electrode layer in such a way as to obtain Mn and Si deposits according to ANSI/AWS standard A5.1-91. The shielded metal arc welding (SMAW) method was used with heat inputs of 1.5 kJ/mm and 2.5 kJ/mm. The tensile property, Charpy-V impact, and microhardness tests were performed to measure the mechanical properties of the weld metal. The observation of the metallographic structure was performed using an optical microscope. The results showed that with the increase of Mg layer content, the metal-oxygen level decreased, and the content of Mn and Si increased. The toughness and tensile strength of AH-36 steel improved, and the optimal Mg content is determined.
Welding of dissimilar metals involves different types of metals which have different chemical composition, mechanical and thermal properties. This paper presents a study on dissimilar metal weld between type 304 stainless steel and SS400 carbon steel. The steel plates were welded by using different filler metals (solid wire, flux-cored wire) and different shielding gases (100%CO2, 90%Ar+10%CO2). Then the weldments were observed by optical microscope, scanning electron microscope and EDX analysis. It seems that the weldments which were welded by using 100%CO2 shielding gas have significant amount of inclusions in weld metal compared to 90%Ar+10%CO2 shielding gas mixture. The EDX analysis shown the inclusions are oxides which consist of some elements (C, Si, Cr, Mn) with O. The weldment which was welded by using 90%Ar+10%CO2 shielding gas mixture and solid wire has much less inclusions in weld metal.
ABSTRAK
Perkembangan teknologi di bidang perindustrian yang semakin maju tidak dapat dipisahkan dari proses pengelasan, salah satunya adalah welding repair. Perbaikan pengelasan bisa mempengaruhi suatu prosedur untuk dapat menghasilkan komponen yang aman dan mampu digunakan sesuai dengan ketentuannya. Kekuatan sambungan las harus diperhatikan dan dijamin kekuatannya, sehingga diharapkan minimal kekuatannya sama dengan kekuatan base metal, khususnya material yang digunakan untuk poros. Tujuan dari penelitian ini adalah membandingkan kualitas mekanik antara raw material baja paduan rendah kekuatan tinggi (HSLA) AISI 4340 dengan material yang sudah dilas. Sehingga akan didapat informasi mengenai kekuatan perubahan sifat mekanik dari sambungan las material AISI 4340 setelah di welding repair dibandingkan dengan raw material AISI 4340.
Metode proses pengelasan yang digunakan adalah SMAW (Shielded Metal Arc Welding) DC polaritas terbalik dengan arus 70 Ampere dan 100 Ampere, elektroda yang dipakai E7016 dan E7018 diameter 3,2 mm serta kampuh yang digunakan adalah kampuh V-Groove dengan sudut 60°. Material uji adalah AISI 4340. Pengujian yang dilakukan adalah uji tarik, uji impak dan uji kekerasan.
Hasil akhir dari penelitian ini telah didapat nilai kekuatan tarik material hasil pengelasan mengalami penurunan sebesar 0,26% dibanding raw material. Nilai rata-rata kerja patah dan nilai ketangguhan material hasil pengelasan mengalami penurunan terhadap raw material, yaitu sebesar 13,73% untuk kerja patah dan 9,18% untuk nilai ketangguhan. Nilai rata-rata kekerasan material hasil pengelasan juga mengalami penurunan 1,64% terhadap raw material. Kesimpulan yang diperoleh dari penelitian ini adalah material AISI 4340 tidak dapat dilakukan welding repair menggunakan metode SMAW dengan elektroda E7018 diameter 3,2 mm.
Kata Kunci : Welding Repair, Las SMAW, AISI 4340, Sifat Mekanik Material
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