Analisis Pengaruh Variasi Temperatur Interpass pada Pengelasan Creusabro 8000 Terhadap Sifat Mekanik dan Struktur Mikro pada Scoop Grab Bucket Ship Unloader

Ghozi, Moch (2024) Analisis Pengaruh Variasi Temperatur Interpass pada Pengelasan Creusabro 8000 Terhadap Sifat Mekanik dan Struktur Mikro pada Scoop Grab Bucket Ship Unloader. Diploma thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Salah satu komponen terpenting dari Grab Bucket ship unloader adalah scoop yang terbuat dari lembaran plat Creusabro 8000 yang telah dibending. Scoop disambung pada rangka dengan metode pengelasan Shielded Metal Arc Welding (SMAW). Namun, sering terjadi kegagalan berupa retak dingin (cold crack) di daerah HAZ akibat pengelasan di balik scoop. Cold crack muncul setelah pengerasan las, disebabkan oleh pembentukan fase martensite dan Hydrogen embrittlement di HAZ. Untuk mencegahnya, diperlukan kontrol interpass temperature yang tepat. Penelitian ini menganalisis pengaruh variasi temperatur interpass (200°C, 250°C, dan 300°C) pada pengelasan Creusabro 8000 dengan ketebalan 12 mm. Pengelasan dilakukan menggunakan elektroda seri E7016 Ø3,2 mm dengan flux rendah hidrogen, butt joint single V-groove dengan sudut bevel 45°, polaritas DCEP, dan posisi pengelasan 1G sebanyak 5 layer. Guna memvalidasi pengaruh interpass temperature terhadap sifat mekanik pada hasil pengelasan, maka akan dilaksanakan pengujian uji tarik, uji kekerasan dan uji metalografi. Hasil uji tarik dan uji kekerasan menunjukkan kecenderungan penurunan nilai yield stress, ultimate tensile stress dan kekerasan pada logam las (weld metal) seiring meningkatnya temperatur interpass, dengan nilai tertinggi didapat pada temperatur 200°C masing-masing yaitu 606,43 MPa, 647,77 MPa dan 10,67 HRC dengan patahan uji tarik terjadi di weld metal. Hasil uji metalografi menunjukkan peningkatan ukuran butiran mikrostruktur seiring naiknya temperatur interpass, dengan butiran didominasi oleh fase ferrite dan pearlite, dan ukuran rata-rata 88,13 μm² pada 200°C, 89,74 μm² pada 250°C, dan 90,31 μm² pada 300°C.
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One of the most important components of the Grab Bucket ship unloader is the scoop, made from bent Creusabro 8000 plates. The scoop is welded to the frame using the Shielded Metal Arc Welding (SMAW) method. However, cold cracks frequently occur in the Heat Affected Zone (HAZ) due to welding behind the scoop. Cold cracks appear after welding hardening, caused by the formation of martensite phase and hydrogen embrittlement in the HAZ. To prevent this, proper control of the interpass temperature is required. This study analyzes the effect of varying interpass temperatures (200°C, 250°C, and 300°C) on welding 12 mm thick Creusabro 8000. Welding was performed using E7016 electrodes Ø3.2 mm with low hydrogen flux, butt joint single V-groove with a 45° bevel angle, DCEP polarity, and 1G welding position with 5 layers. To validate the effect of interpass temperature on the mechanical properties of the welds, tensile tests, hardness tests, and metallographic examinations will be conducted. The results from tensile and hardness tests indicate a trend of decreasing yield stress, ultimate tensile stress, and weld metal hardness with increasing interpass temperature, with the highest values observed at 200°C, namely 606.43 MPa, 647.77 MPa, and 10.67 HRC, respectively, with tensile test fractures occurring in the weld metal. Metallographic results show an increase in microstructure grain size with higher interpass temperatures, dominated by ferrite and pearlite phases, with average sizes of 88.13 μm² at 200°C, 89.74 μm² at 250°C, and 90.31 μm² at 300°C.

Item Type:	Thesis (Diploma)
Uncontrolled Keywords:	Cold Crack, Creusabro 8000, E7016, Interpass Temperature, Martensite, Pengelasan, Weld Metal., Cold Crack, Creusabro 8000, E7016, Interpass Temperature, Martensite, Welding, Weld Metal.
Subjects:	T Technology > TS Manufactures T Technology > TS Manufactures > TS227 Welding.
Divisions:	Faculty of Vocational > Mechanical Industrial Engineering (D4)
Depositing User:	Moch Ghozi
Date Deposited:	01 Aug 2024 03:46
Last Modified:	01 Aug 2024 03:46
URI:	http://repository.its.ac.id/id/eprint/111059

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