Influência dos tratamentos térmicos do aço API X 70 para aplicações na indústria petróleo e gás

Abstract

This work was inspired by the deep study of physical metallurgy with the purpose of studying the microstructures found. The methodology was divided in a detailed study of the microstructure associated to a set of laboratory practices, with respect to the influence of the thermal treatments in the microstructures and hardness of API 5L X-70 Steel, cooled in water, oil and nitrogen baths, to obtain different cooling rates. To understand this study, thermal treatments of normalization and tempering, hardness and metallographic analysis were carried out on the referred steel. Subjects were discussed on microstructures registered by optical microscopy and confirmed in TermoCalc® and relevant phases to maintain the quality of the mechanical properties. The results found clarify a better choice of temperatures and chemical composition for the desired microstructure, even finding a multiphase structure that can improve some mechanical properties and restrict others.