Investigations of Mechanical Properties Microstructure and Corrosion Behavior of Duplex Stainless Steel Weld

Abstract

quotDuplex stainless steel (DSS) comprises of dual phase with austenite and ferrite in equal proportion exhibits excellent mechanical and corrosion resistance properties in various aggressive environments like marine, oil and gas, pharmaceuticals, power plants and other engineering applications. Thus duplex stainless steel is found to be a candidate material from last two decades and it creates enormous focus for manufacturers, end users and researchers due to its globally fast demand, growth and consumption in the field of fabrication. While austenitic stainless steel is widely used in various sectors and having major production rate but the fluctuated Ni price creating the major issue for manufacturers and end users which emphasis on overall need of an industry. Welding of duplex stainless steel is very critical and challenging because of metallurgical changes, intermetallic phase formation, embrittlement, imbalanced austenite/ferrite ratio resulting poor ductility, solidification cracking and corrosion susceptibility. Many sectors, where thick sections are used for higher productivity which recommends appropriate consumables, controlled heat input, cooling rate, optimized interpass temperature and defect free weld joint. newlineIn present work, experiments are designed based on central composite design using design expert with appropriate input variables. Input variables are selected in accordance with essential process parameters as per ASME Sec. IX such as welding current, interpasss temperature and gas flow rate. Experiments are performed on DSS 20 mm thick plate having double V butt joint, welded by gas tungsten arc welding process with purging on one side and shielded metal arc welding process on other side followed by multipasss using E/ER2209 electrode at controlled heat input of 0.5 1.5 kJ/mm. Weldment was investigated for output variables such as tensile strength, ferrite measurement, impact strength, hardness and intergranular corrosion by cutting across the weld. Microscopic examination is carried out usin