THE USE OF PULSE-ECHO ULTRASONIC METHOD FOR DETERMINING CARBIDE FRACTION IN CAST AUSTENITIC STAINLESS STEEL

• Main Author: Siddiq, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/63277
• Institution: Institut Teknologi Bandung

High-temperature materials are identical with carbide compounds’ formation, for example, Cast Austenitic Stainless Steel (CASS) material is used as a reformer tube. Carbide in CASS material can be both beneficial and detrimental so it needs to be considered. In its application in industry, the degradation process of CASS material can be characterized by an increase in the carbide fraction in the material. In this study, pulse-echo ultrasonic method was carried out to determine the correlation of longitudinal wave propagation speed with the carbide fraction. Characterization and tests carried out included Optical Emission Spectroscopy (OES), metallography, Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Diffraction (XRD), Rockwell B hard test, and ultrasonic testing. The carbide area fraction of as-received and solution treatment (ST) specimens consisting of ST 1, ST 2, and ST 3 were 23.54; 18.89; 14.26; dan 17.73%, respectively. The longitudinal wave propagation velocity (VL) of as-received specimen, ST 1, ST 2, and ST 3 were 6,047, 5,950, 5,596, and 5,873 m/s, respectively. The as-received and ST specimens both contain chromium and niobium carbides. Furthermore, it was found that there was an increase in VL as the carbide fraction increased. This research hopes that it can be an anticipatory step to avoid failure in the industry.