Dissimilar metal welds between austenitic stainless steel and carbon steel are commonly used in oil and gas industries for certain reasons. The objective of this research is to asses the effect of filler metal and shielding gas on the microstructure and hardness of dissimilar lap joint of type 304 austenitic stainless steel to JIS SS400 low carbon steel. For the purpose of this investigation, the weldments were produced using flux-cored arc welding (FCAW). Three types of filler metals (E316L, E309L and E308L) and two different gas compositions (100%CO2 and 90%Ar+10%CO2) were selected to be used. Each of the weldments were analyzed on the microstructure characteristic and hardness profile of base metal (BM), heat affected zone (HAZ) and weld metal (WM) using optical microscope and microhardness Vickers. The metallographic examination revealed HAZ-SS400 contains martensites. Both HAZ-304 and WM show austenitic microstructure, with columnar and cellular sub-structures present at WM. The hardness profile of HAZ-304 is higher than BM-304, it may be attributed to the presence of the fine grains in HAZ-304 due to high temperature during welding. The hardness profile of WM-E309L exhibited the hardness from HAZ to WM tend to decrease linearly, while WM-E316L and WM-E308L showed the hardness from HAZ to WM also decreased but drastically dropped at fusion line (FL). The welds using E309L offer the best result in the point of view homogeneity of the hardness profile.
Proses pengelasan merupakan teknologi penyambungan pada logam yang sering digunakan. Metoda pengelasan GMAW telah banyak digunakan secara luas pada penyambungan pipa penyalur (pipe line), pipa kostruksi, proses pemipaan (piping process), dll. Baja API 5L Grade B adalah salah satu bahan yang distandarkan oleh API untuk penggunaan/aplikasi perpipaan pada perusahaan minyak dan gas (oil and Gas). Dalam instalasinya dibutuhkan hasil penyambungan yang baik tanpa terbentuknya cacat pada sambungan sesuai dengan standar API. Variasi arus (100, 135 dan 160A) pada proses pengelasan GMAW akan berpengaruh terhadap heat input dan kelarutan (dilution) antara logam dasar dengan logam pengisi yang dapat menyebabkan perubahan sifat fisik dan sifat mekanik pada sambungan pipa.
Kualitas/mutu sambungan dapat dikaji dengan melakukan pengujian supaya dapat diketahui sifat fisik dan sifat mekanik hasil sambungan pipa dengan variasi arus pada metoda GMAW. Metoda pengujian yang dilakukan antara lain : uji tarik, uji nick break dan uji lengkung, sedangkan perubahan struktur mikro dikaji dengan analisa metalografi.
This study aims to determine the differences between students’ learning outcomes using kinesthetic learning demonstration learning methods on the oxy-acetylene welding practice subject for welding technique class grade X students at Sayegan 1 Vocational High School. The research method used was an experimental method with quasi-experimental design research as the research type. The results showed differences between the learning outcomes of welding technique class grade X students between before they were given the treatment and after, using the kinesthetic learning style demonstration method. It could be seen in the results of the assessment: the average post-test scores in the two classes are the highest on the aspect of the assessment criteria number 2 for the experimental and control groups with a value of 0.4. The lowest is in criterion number 8, with a value of 0.25 for the experimental group. For the control group, the lowest is on criterion number 4, with a value of 0.11. This was proved by the increase of the average score on assessment criteria before and after the treatment. Thus, the demonstration method’s effect using kinesthetic learning style on oxy-acetylene welding practices of welding technique class grade X students at Sayegan 1 Vocational High School.
Bantalan Luncur (Bush) pada poros sepatu rem kereta api berfungsi membantu proses pengereman yang terjadi pada kereta api yang akan berhenti. Kegagalan bantalan luncur dalam membantu proses pengereman yang terjadi pada kereta api akan mengakibatkan kereta bisa tergelincir atau yang lebih fatal akan mengakibatkan terjadinya kecelakaan. Kerusakan pada bantalan luncur ini terjadi karena adanya konsentrasi tegangan sehingga tegangan yang diterima melebihi kekuatan dari bantalan luncur. Akibatnya bantalan luncur mengalami patah. Tegangan yang terjadi akibat adanya konsentrasi tegangan sebesar 21,32 kgf/mm2 sedangkan tegangan yang diijinkan adalah 16,4 kgf/mm2 . Perbedaan yang besar ini menyebabkan terjadinya deformasi dan patah pada bantalan luncur. bentuk patahan yang terjadi berupa patah transgranular. Sehingga pada material bush yaitu patah transgranular .
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