Effect of Different Heat Treatment Conditions on the Microstructure and Mechanical Properties of Inconel 718 Nickel Based Super Alloy Used in Petroleum Production

Abstract The development of the oil and gas industry in Brazil in the last decades has led to petroleum extraction in deeper water and extremely corrosive environments, associated to the presence of H 2 S, CO 2 and chlorides, as well as mechanical loads caused by the wave's movement and sea streams. In these adverse conditions the search for new materials with adequate properties for this kind of application is intense. In the present work a study is carried out on the microstructure and mechanical properties of the super alloy Inconel 718 subjected to different temperatures and times of solution and aging heat treatments. This material, usually used in the fabrication of aircraft motor and energy generation turbines, in the present case is proposed for the fabrication of bolts used in the fixation of submarine pipes for oil extraction. The use of techniques like optical microscopy, automatic image analysis, scanning electron microscopy (SEM) and hardness and tensile tests, allowed the identification of the ideal conditions for heat treating this material for this kind of application.