Correlação entre microestrutura e susceptibilidade à corrosão sob tensão de componente de aço 2,5Cr-1,0Mo impresso por manufatura aditiva com arame e arco

Abstract

Susceptibility to stress corrosion cracking in the presence of H2S and hydrogen embrittlement in marine environments are problematic in this context of application. In this work, an additive manufacturing part was manufactured with 2.5Cr-1.0Mo steel using the Gas Metal Arc Welding – Cold Metal Transfer (GMAW-CMT) process with oscillated passes, heat treated it and compared its performance in service with a forging of similar chemical composition. The microstructure was investigated by thermodynamic simulations, optical microscopy, scanning electron microscopy and X-ray diffraction. The mechanical properties and susceptibility to stress corrosion were evaluated using Vickers microhardness and tensile tests under low strain rates in a medium containing H2S + CO2 balance and synthetic seawater environment with cathodic protection. The additive manufacturing materials were mechanically characterized in the horizontal and vertical directions in relation to the direction of advance of the deposited layers. It was observed that all materials were susceptible to stress corrosion. But the materials manufactured with additive manufacturing showed better performance in the properties of ratio in area reduction, ratio in plastic elongation, yield limit and maximum resistance than the forged materials both when requested in horizontal and vertical direction in all tested means, that is, if explains in terms of greater microstructural refining, confirming the efficiency of this new technology compared to traditional processes.