Fadihillah, Fairuz Farand (2021) Pengaruh Variasi Temperatur Post-Weld Heat Treatment dan Shot Peening Terhadap Laju Korosi Sambungan Las pada Baja Karbon Rendah. Sarjana thesis, Universitas Brawijaya.
Abstract
Fairuz Farand Fadihillah, Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya, Juni 2021, Pengaruh Variasi Temperatur Post-Weld Heat Treatment dan Shot Peening Terhadap Laju Korosi Sambungan Las pada Baja Karbon Rendah, Dosen Pembimbing: Teguh Dwi Widodo dan Rudianto Raharjo Industri perkapalan adalah salah satu pasar paling kompetitif, sangat terbuka, dan tertua di dunia. Pada awal tahun 2019, jumlah dari seluruh armada kapal dunia berada pada angka 95.402 unit kapal di Indonesia sendiri terdapat 240 galangan kapal nasional dengan total kapasitas 225.000 GT. Statistik tentang kerusakan lambung kapal menunjukan bahwa korosi merupakan penyebab dominan dari kegagalan struktur kapal, dimana korosi yang terjadi pada material lambung kapal baja karbon rendah structural steel SS400 dipengaruhi oleh lingkungan dan kandungan tegangan sisa dari material. Dengan memodifikasi kandungan tegangan sisa dari material sambungan las GMAW pada structural steel SS400 melalui perlakuan Post-Weld Heat Treatment (PWHT) dan Shot Peening maka dapat meningkatkan ketahanan korosi dari sambungan las struktural kapal nantinya. Dalam proses PWHT temperatur yang semakin tinggi dapat mempengaruhi pelepasan kandungan tegangan sisa dari material dan proses shot peening berfungsi untuk memberikan tegangan tekan sisa yang berguna untuk meningkatkan ketahanan material. Untuk pengoptimalisasi tegangan tekan sisa yang tercipta berada pada lapisan yang lebih dalam maka diperlukan proses PWHT terlebih dahulu sebelum proses shot peening. Variabel bebas yang digunakan pada penelitian ini ialah variasi temperatur PWHT sebesar 550 °C, 620 °C, 690°C , 760 °C, 830 °C dan variasi kelima temperatur dengan penambahan proses shot peening. Pengujian kekerasan dilakukan pada beberapa titik spesimen untuk mengetahui daerah hasil pengelasan (weld, HAZ, dan logam induk) sebagai referensi lokasi penembakan shot peening. Kemudian dilakukan penembakan shot peening dengan diameter bola 3 mm, diameter nozzle 6 mm, dan tekanan kompresor 8 bar pada daerah HAZ dan Weld. Setelah itu spesimen dilakukan uji laju korosi menggunakan Palm Sense. Pada proses ini terdapat working electrode ,counter electrode dan reference electrode dengan Structural Steel SS400 bertindak sebagai working electrode. Larutan air laut pantai Kenjeran Surabaya dengan konsentrasi NaCl 1,05% digunakan sebagai lingkungan uji korosi untuk mensimulasikan kondisi laut yang akan dilalui kapal. Uji Scanning Electron Microscope (SEM) dilakukan untuk mengamati permukaan setelah terkorosi, Adapun pengujian mikrostruktur dan makro dilakukan untuk mengamati perbedaan masing-masing spesimen. Hasil yang didapatkan dari penelitian ini ialah bahwa meningkatnya temperatur pada proses PWHT dapat meningkatkan ketahanan korosi dari material dan spesimen dengan perlakuan shot peening memiliki laju korosi yang lebih rendah dibandingkan spesimen tanpa perlakuan shot peening. Namun pada temperatur yang lebih tinggi dari titik AC1 dapat mengakibatkan inklusi kotoran pada batas butir dan presipitasi fase karbida dan ferrite yang meningkatkan laju korosi dari spesimen. Kata kunci: Structural Steel SS400, Tegangan Sisa, Shot Peening, Post-Weld Heat Treatment, Laju Korosi
English Abstract
Shipping industry is one of the most competitive, highly open and oldest markets in the world. At the beginning of 2019, total number of the world's ship fleets stood at 95,402 units of ships. In Indonesia alone, there were 240 national shipyards with a total capacity of 225,000 GT. Statistics on ship’s hull damage show that corrosion is the dominant cause of structural failure of ships, where corrosion that occurs in the hull material of low carbon steel structural steel SS400 is influenced by the environment and residual stresses of the material. By modifying the residual stresses content of the GMAW welded joint of SS400 structural steel through Post-Weld Heat Treatment (PWHT) and Shot Peening, it can increase the corrosion resistance of the ship's structural welded joints later on. In the PWHT process, the higher temperature it took, the more residual stress content released from the material and the shot peening process serves to provide residual compressive stress to the material, which is useful for increasing corrosion resistance of the material. To optimize the residual compressive stress which created by shot peening in a deeper layer, then the PWHT process is needed to occurred first before the shot peening process. The independent variables used in this study were variations in PWHT temperature of 550 °C, 620 °C, 690 °C, 760 °C, 830 °C and the fifth variation of temperature all together with the addition of the shot peening process. Hardness testing was carried out at several specimen points to determine the weld area (Weld, HAZ, and Base Metal) as a reference for shot peening shooting locations. Then shot peening was carried out with a ball diameter of 3 mm, nozzle diameter of 6 mm, and compressor pressure of 8 bar in the HAZ and Weld areas. After that, the specimen was tested for corrosion rate using Palm Sense polarization unit. In this process there are working electrodes, counter electrodes and reference electrodes, with Structural Steel SS400 acting as the working electrode. The seawater solution of Kenjeran beach Surabaya with a NaCl concentration of 1.05% was used as a corrosion test environment electrolyte to simulate the sea conditions that will be passed by the ship. The Scanning Electron Microscope (SEM) test was carried out to observe the surface after it was corroded. The microstructure and macro tests were carried out to observe the differences between each specimen variations. The results obtained from this study are that increasing the temperature in the PWHT process can increase the corrosion resistance of the material and specimens with shot peening treatment have a lower corrosion rate than specimens without shot peening treatment. However, at temperatures higher than the AC1 point, it can cause inclusion on grain boundaries and precipitation of carbide and ferrite phases which increase the corrosion rate of the specimen. Keyword: Structural Steel SS400, Residual Stresses, Shot Peening, Post-Weld Heat, Treatment, Corrosion Rate
Other obstract
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| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | 621.8 |
| Uncontrolled Keywords: | Kata kunci: Structural Steel SS400, Tegangan Sisa, Shot Peening, Post-Weld Heat Treatment, Laju Korosi-- Structural Steel SS400, Residual Stresses, Shot Peening, Post-Weld Heat, Treatment, Corrosion Rate |
| Subjects: | 600 Technology (Applied sciences) > 621 Applied physics > 621.8 Machine engineering |
| Depositing User: | Unnamed user with email gaby |
| Date Deposited: | 20 Oct 2021 05:37 |
| Last Modified: | 25 Feb 2022 16:05 |
| URI: | http://repository.ub.ac.id/id/eprint/184312 |
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