Studi Potensi Inisiasi Retakan Korosi Tegangan Baja Tahan Karat Super Duplex Uns S32760 Pada Heat Treatmet Dengan Media Pendinginan Berbeda

Halimi, Ahamad Dzulfikri (2021) Studi Potensi Inisiasi Retakan Korosi Tegangan Baja Tahan Karat Super Duplex Uns S32760 Pada Heat Treatmet Dengan Media Pendinginan Berbeda. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Penggunaan baja tahan karat super duplex secara luas dapat ditemukan pada sistem pembangkit listrik tenaga uap,industri pulp dan kertas, serta dalam industri ekstraksi logam, terutama pada struktur sistem perpipaan. Paduan ini memiliki kemampuan las yang unggul dan sifat mekanik yang lebih baik daripada baja tahan karat austenitik. Namun karena baja tahan karat super duplex mempunyai struktur dua fase, sifatnya sangat bergantung pada komposisi dan riwayat termal. Tujuan dari penelitian ini adalah untuk menginvestigasi pengaruh rekayasa perlakuan panas terhadap inisiasi retakan akibat Stress Corrosion Cracking (SCC) baja Super Duplex Stainless Steel (SDSS) UNS S32760. Metode yang digunakan adalah eksperimen dan simulasi. Pada eksperiment, dilakukan heat treatment dengan tiga variasi media quenching yang di pakai dalam penelitian ini yaitu, air, oli dan udara (temperatur ruang). Pada simulasi, dibuat model elemen hingga dan dikenakan defleksi tetap pada specimen C-ring sebesar 0,7 mm dan 1,8 mm. dan variasi lingkungan korosif dengan larutan 3,5% NaCl, 1M NaOH dan 1M selama 720 jam. Hasil penelitian didapatkan kekuatan tarik spesimen dengan media quenching air cenderung lebih tinggi sedangkan untuk distribusi mikrostruktur muncul fasa sigma (σ) pada sampel dengan media quenching air presentase sebesar 40,29 % Berdasarkan hasil analisis pemindaian SEM, menunjukkan seluruh feritnya bertransformasi menjadi fasa austenit sekunder dan fasa sigma (σ) melalui reaksi eutektoid, akibatnya baja tahan karat UNS S32760 Super Duplex tersebut mengalami perilaku korosi yang anodik dengan Corrosion Rate tertinggi pada larutan 1M 3,7454 mmpy. hasil pengamatan pada inisiasi akibat pengaruh pemuatan mekanis yang di ekspose pada variasi lingkungan korosif dimana inklusi senyawa dengan laju korosi yang tinggi secara brsamaan di kenai beban mengakibatkan munculnya inisiasi dimulai dari pusat daerah terekspos, retakan akan terjadi pada sisi garis tengah karena distribusi tegangan bergeser di sekitar C-Ring.
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Super duplex stainless steels used more widely, it can be found in steam power systems, pulp and paper industry, and also metal fefining industry especially in piping system structures, these alloys have superior weldability and better mechanical properties than austenitic stainless steels. However, super duplex stainless steels have a two-phase structure, their properties depends on their composition and thermal history. The purpose of this study is to investigate the effect of solution anealing treatment on mechanical properties and corrosion behaviour of Super Duplex Stainless Steel (SDSS) UNS 32760. The method used is experiment and simulation. In the experimental section, a heat treatment was carried out by three varying, quenching media, which is water, oil and air (room temperature). The specimen was immersed in a solution of 3.5% NaCl, 1M NaOH caustic solution and 1M acidic solution to find out if there are potential cracks. Immersion is carried out for 720 hours. Furthermore, in the simulation section, a finite element model is created from the C-ring specimen and subject to a fixed deflection of 0.7 mm and 1.8 mm. Material properties as finite element simulation input are obtained from the results of the specimen tensile test (SDSS) UNS 32760. The results showed that the tensile strength of the specimens with water quenching media tended to be higher, while for the microstructure distribution The appearance of intermetallic phases, especially in samples with water quenching media, the percentage of sigma phase (σ) was 40.29%. the results of SEM scanning analysis, it shows that all ferrite is transformed into secondary austenite phase and sigma phase (σ) through the eutectoid reaction, as a result the UNS S32760 Super Duplex stainless steel experiences anodic corrosion behavior with a Corrosion Rate in a 1M solution 3.7454 mmpy. Results of observations due to the effect of mecanical loading being exposed to variations in the corrosive environment where inclusion compounds with high corrosion rates are simultaneously subjected to loads due to initiation starting from the center of the exposed area, cracks will occur on the side of the center line because the stress distribution shifts around the C-Ring.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Stainless steel super duplex, Media Quenching, Metode elemen hingga. Super duplex stainless steel, Quenching Media, Finite element method, Stress Corrosion Cracking.
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA418.74 Corrosion and anti-corrosives T Technology > TN Mining engineering. Metallurgy > TN690 Metallography. Physical metallurgy
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Material & Metallurgical Engineering > 27101-(S2) Master Thesis
Depositing User:	AHMAD DZULFIKRI HALIMI
Date Deposited:	02 Mar 2021 02:34
Last Modified:	02 Mar 2021 02:34
URI:	http://repository.its.ac.id/id/eprint/83059

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