Philippine Journal of Science
152 (3): 989–998, June 2023
ISSN 0031 – 7683
Date Received: 26 May 2022

Microstructures of Austenitic Stainless Steel
56Fe25Ni16.6Cr0.9Si0.5Mn Solid-treated
with Different Cooling Rates

Mohammad Dani1, Ferhat Aziz1*, Parikin Farihin1, Arbi Dimyati1,
Sulistioso Giat Sukaryo1, Joshua Gunawan Lesmana2, Andon Insani1,
Salim Mustofa1, Mardiyanto Panitra1, and Ching An Huang3

1Nuclear Reactor Technology Research Center, National Research and Innovation
Agency (BRIN), Kawasan Puspiptek Serpong, Tangerang Selatan 15314 Indonesia
2Department of Physics Energy Engineering, Faculty of Clean Energy
and Climate Change, Surya University, Kota Tangerang 15143 Indonesia
3Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan

*Corresponding author: ferhat.aziz@brin.go.id

[Download]
Dani M et al. 2023. Microstructures of Austenitic Stainless Steel 56Fe25Ni16.6Cr0.9Si0.5Mn
Solid-treated with Different Cooling Rates. Philipp J Sci 152(3): 989–998.
https://doi.org/10.56899/152.03.19

 

ABSTRACT

A new synthesized 56Fe25Ni16.6Cr0.9Si0.5Mn austenitic stainless steel (ASS) was produced through casting and then annealing and normalizing at 1100 °C, followed by cooling at different rates. Microstructures of the samples were studied by using X-ray and neutron diffractometers, scanning, and transmission electron microscopes. The stainless steel had a face center cubic structure (X-ray diffraction profile). The microstructure of ASS consists of γ-austenite matrix and high Cr carbide particles in the interior grains and grain boundaries. It seemed that the annealing process affected information of γ-austenite grain size in the ASS, growing larger compared to grain size formed in the normalizing process, similarly by cooling into the air, water, and oil media. The M23C7 islands in the grain boundary formed into a larger size after annealing or normalizing processes, and in addition, the island shape was more elongated. No significant changes were found concerning the particle size and shape of M7C6 at the grain boundary of the ASS after annealing or normalizing. Neutron diffraction patterns confirmed the Fm3m space group symmetry of ASS as obtained by the XRD method, therefore establishing ASS as an austenite phase. Results of the uniform deformation method (UDM) analysis applied upon the high-resolution powder neutron diffractometer (HRPD) intensity showed that the deformation strain was 2.3705 × 10–4. TEM results for ASS showed that the sizes of rectangular precipitates ranged from 63 × 32 nm to 84 × 42 nm with larger-sized irregulars reaching about 190 nm across. All these results showed that an ASS has been successfully synthesized and that it has a promising future to be used as a high-temperature structural material.