Mantika, Fitriyani Aditiya (2018) Pengaruh Heat Input Pada Pengelasan Dissimilar Metal SS304H Dan T22 Dengan Proses GTAW Terhadap Distribusi Kekerasan Dan Kandungan Delta Ferrite. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Pengelasan tidak sejenis merupakan salah satu metode untuk penyambungan logam berbeda contohnya antara stainless steel dengan low alloy steel, sambungan ini digunakan pada pembangkit listrik bagian tube di boiler, dikarenakan tube di boiler bekerja di suhu dan tekanan berbeda sehingga akan mempengaruhi jenis material yang digunakan. Akan tetapi terdapat beberapa kekurangan, yaitu akibat perbedaan komposisi kimia antara kedua material yang di sambungkan sepanjang garis fusi, membuat perbedaan struktur mikro sehingga sifat mekanik juga berbeda. Perbedaan ini membuat sambungan akan rentan terhadap kegagalan. Selain itu perbedaan koefisien thermal masing-masing material juga membuat degradasi di struktur mikro pada zona fusi, sehingga membuat munculnya tegangan yang mengakibatkan rentannya terjadi kelelahan komponen maupun retak.
Dalam penelitian ini dilakukan pengelasan tidak sejenis antara SS304H dan T22 dengan variasi heat input, dimana variasi heat input yang digunakan adalah 3.6KJ/mm, 3.1KJ/mm dan 2.9 KJ/mm. Ketiga variasi pengelasan ini menggunakan metode gas tungsten arc welding (GTAW) dengan filler ER309. Setelah dilakukan proses pengelasan dilakukan pengujian kekerasan dengan microvickers untuk mengetahui distribusi kekerasan pada sambungan las, metallography serta pengujian nilai delta ferrite.
Dari penelitian ini didapatkan hasil bahwa distribusi kekerasan berbanding terbalik terhadap heat input karena semakin tinggi nilai heat input nilai kekerasan semakin menurun hal ini dikarenakan jika nilai heat input tinggi pendinginan semakin lamban dan menyebabkan nilai kekerasan menurun. Nilai heat input berbanding lurus pada kandungan FN dimana semakin tinggi heat input nilai FN semakin tinggi, dimana nilai FN mewakili kandungan delta ferrite pada material. Pada struktur mikro material di daerah HAZ SS304H ditemukan presipitasi karbida pada batas butir yang menurunkan kadar kromium disekitarnya yang membuat daerah tersebut akan rawan terkena korosi batas butir dan menyebabkan kekerasan material tidak merata.
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Dissimilar metal welding (DMW) is one method for connecting different metals such as stainless steel with low alloy steel, this connection is used in the tube power plant in the boiler, because the tube in the boiler works at different temperatures and pressures that will affect the type of material used. However, there are some drawbacks, namely due to differences in chemical composition between the two materials that are connected along the fusion line, making the differences in micro structure so that the mechanical properties also different. This difference makes the connection vulnerable to failure. In addition, differences in thermal coefficients of each material also create degradation in the microstructure of the fusion zone, resulting the emergence of stresses that cause vulnerability to component fatigue and cracking.
In this research, DMW between SS304H and T22 with variation of heat input, where the heat input are 3632.18 J/mm, 3184.91 J/mm and 2938.81 J/mm. These three welding variations use gas tungsten arc welding (GTAW) with ER309 as filler. After the welding process is done the material were tested mechanical testing, examine the microstructure of the weldment and measure delta ferrite content.
From this research the result shows that the hardness distribution is inversely related to heat input because the higher the value of heat input hardness value decrease this is because if the value of heat input high cooling more slowly and cause hardness value decrease. The heat input value is directly proportional to the FN content where the higher heat input the higher FN value, where the FN value represents the delta ferrite content in material. On the microstructure of HAZ SS304H area, carbide precipitation is found carbide precipitation at the grain boundary where it make the chromium levels lowers which make area vulnerable to grain boundary corrosion.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSM 671.52 Man p-1 3100018074465 |
| Uncontrolled Keywords: | dissimilar; heat input; GTAW; FN; welding; hardness; pengelasan beda jenis; heat input; kekerasan |
| Subjects: | T Technology > TN Mining engineering. Metallurgy > TN879.6 Welding T Technology > TS Manufactures |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Fitriyani Aditiya Mantika |
| Date Deposited: | 20 Mar 2018 04:07 |
| Last Modified: | 30 Mar 2020 02:37 |
| URI: | http://repository.its.ac.id/id/eprint/50362 |
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