Optimasi Parameter Solution Annealing Pada Paduan 25Cr-35Ni+Nb Steam Reformer Tube Menggunakan Response Surface Methodology

Arasy, Tarekh Sufi Bara (2026) Optimasi Parameter Solution Annealing Pada Paduan 25Cr-35Ni+Nb Steam Reformer Tube Menggunakan Response Surface Methodology. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Paduan 25Cr–35Ni+Nb banyak digunakan sebagai material steam reformer tube karena memiliki ketahanan yang baik pada temperatur tinggi. Namun, setelah beroperasi selama ±130.000 jam, material mengalami degradasi mikrostruktur yang berdampak pada penurunan sifat mekanis. Penelitian ini bertujuan untuk menganalisis pengaruh variasi temperatur dan holding time solution annealing terhadap mikrostruktur dan kekerasan serta menentukan parameter optimum menggunakan Response Surface Methodology (RSM). Penelitian dilakukan menggunakan variasi temperatur 1050°C, 1125°C, dan 1200°C serta holding time 20, 40, dan 60 menit, kemudian dilanjutkan dengan water quenching. Karakterisasi material dilakukan menggunakan Optical Microscope (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), dan X-Ray Diffraction (XRD), sedangkan sifat mekanis dievaluasi melalui pengujian kekerasan Vickers. Data dianalisis menggunakan Response Surface Methodology (RSM) dengan bantuan perangkat lunak Minitab. Hasil penelitian menunjukkan bahwa solution annealing menurunkan area fraction presipitasi dan mengubah morfologi presipitasi menjadi lebih tipis akibat pelarutan sebagian presipitasi, sedangkan perubahan ukuran butir relatif kecil sehingga matriks austenit tetap stabil. Optimasi menggunakan RSM menghasilkan parameter optimum pada temperatur 1133,33°C dan holding time 44,65 menit dengan prediksi kekerasan 180,23 HV0,5. Hasil verifikasi pada temperatur 1135°C dan holding time 45 menit menghasilkan nilai kekerasan 179 ± 8,88 HV0,5 dengan selisih 0,68% terhadap nilai prediksi. Hasil tersebut menunjukkan bahwa parameter optimum mampu mengurangi jumlah presipitasi tanpa menyebabkan perubahan ukuran butir yang signifikan, sehingga menghasilkan nilai kekerasan yang sesuai dengan target optimasi.
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The 25Cr–35Ni+Nb alloy is widely used as a material for steam reformer tubes due to its excellent resistance to high-temperature service conditions. However, after approximately 130,000 hours of operation, the material undergoes microstructural degradation, resulting in a deterioration of its mechanical properties. This study aims to investigate the effects of solution annealing temperature and holding time on the microstructure and hardness of the alloy, as well as to determine the optimum processing parameters using the Response Surface Methodology (RSM). The experiments were conducted using solution annealing temperatures of 1050°C, 1125°C, and 1200°C with holding times of 20, 40, and 60 minutes, followed by water quenching. Microstructural characterization was performed using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-Ray Diffraction (XRD), while the mechanical properties were evaluated through the Vickers hardness test. The experimental data were analyzed using Response Surface Methodology (RSM) with Minitab software. The results showed that solution annealing reduced the precipitate area fraction and produced a thinner precipitate morphology due to partial precipitate dissolution, while the grain size remained relatively unchanged. RSM optimization predicted the optimum parameters at 1133.33°C and 44.65 minutes, with a hardness of 180.23 HV0.5. Experimental verification at 1135°C for 45 minutes yielded 179 ± 8.88 HV0.5, with only 0.68% deviation from the prediction. These findings confirm that the optimum parameters effectively reduced precipitates while maintaining grain stability and achieving the targeted hardness.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	25Cr–35Ni+Nb, steam reformer tube, solution annealing, Response Surface Methodology, mikrostruktur, kekerasan, 25Cr–35Ni+Nb alloy, steam reformer tube, solution annealing, Response Surface Methodology, microstructure, hardness
Subjects:	T Technology > TN Mining engineering. Metallurgy > TN752.I5 Steel--Heat treatment
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Tarekh Sufi Bara Arasy
Date Deposited:	05 Aug 2026 01:53
Last Modified:	05 Aug 2026 01:53
URI:	http://repository.its.ac.id/id/eprint/143559

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