Análise de tratamento térmico no aço inox 410 aplicado a bicos spray de válvula dessuperaquecedora de vapor

Abstract

Stainless steels are widely used in industries due to their high corrosion resistance and high mechanical strength. The stainless steels of the martensitic family have the ability to undergo heat treatment and deliver an increase in their hardness, toughness and ductility, according to the chosen treatment. The present study aims to analyze the microstructure and hardness of AISI 410 steel submitted to different heat treatments as a possible way to increase the durability of spray nozzles used in steam desuperheating valves, where due to the high speed of water injection to reduce the temperature of the vapor, it causes the phenomenon of "erosion-corrosion"in its injector holes, reducing service life and process control. Two conventional heat treatments were used, one of tempering and the other of tempering followed by tempering, in order to verify the changes in the mechanical and microstructural properties of AISI 410 steel. Three reference samples were chosen, three samples for quenching at 950◦C with a soaking time of 25 minutes, and three samples for the tempering process followed by tempering at 275◦C with a soaking time of 2 hours. A metallographic analysis was performed using the optical microscope technique, the hardness analysis was performed using the Rockwell hardness test in a durometer. For the tempered samples in relation to the reference samples, an increase in hardness of about 880% was observed, while for the tempered samples followed by tempering they were 805%.