EFFECT OF THERMAL AGING AND SOLUTION ANNEALING ON THE FORMATION OF THE SIGMA PHASE IN SUPER DUPLEX STAINLESS STEEL UNS S32760

• Main Author: Salsabila, Ainaya
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/83093
• Institution: Institut Teknologi Bandung

The oil and gas industry, especially offshore industries, operates in extremely corrosive and high-pressure environments necessitating materials with high strength, toughness, and corrosion resistance. Super duplex stainless steel (SDSS) is often chosen for its high corrosion resistance, as well as its strength and toughness. However, the application of SDSS is limited because when exposed to heat in the temperature range of 600-1050?, secondary phase formations such as sigma (?), chi (?), carbides, and nitrides occur, which degrade corrosion resistance. A heat treatment process is required to counteract the formation of these secondary phases and restore the strength and corrosion resistance of SDSS. Therefore, this study will conduct experiments and analysis on SDSS through thermal aging to understand the formation of the sigma phase and solution annealing to dissolve the formed sigma phase. This research focuses on one type of SDSS material, UNS S32760. Thermal aging in this study was conducted at temperatures of 700, 800, 900, and 1000°C, and solution annealing was performed at temperatures of 1100, 1200, and 1300°C. The results of these heat treatments were characterized using energy dispersive x-ray spectroscopy (EDS), optical microscopy (OM), and Rockwell hardness testing. The results of this study indicated that phase formation during thermal aging produced a maximum amount of sigma phase at 800°C, and the sigma phase formed during thermal aging will reduce the ferrite phase formed after solution annealing at 1100°C.