Soldagem MAG do aço SAE 4340: análise da microdureza após tratamento criogênico profundo

Abstract

The search for new methods and applicability for the materials behind with it the need for improvements and studies on the mechanical properties of steels. Cryogenic treatment is an alternative for conventional heat treatments, although it is a relatively new area of study. Bibliography shows that cryogenic can be beneficial in several mechanical properties, such as fatigue resistance, increased shelf life of metal components, increased hardness, among other advantages. The present work aims to study and analyze the influence of cryogenic treatment on the SAE 4340 steel alloy welded with MAG process with E70S-6 wire, through Vickers microhardness and impact assay, using three different immersion times in liquid nitrogen (without immersion, 2 hours and 4 hours). The procedures showed a slight increase in hardness and a decrease in impact resistance, indicating that the treatment time despite short transformed part of the austenite retained into martensite.