Avaliação do tratamento criogênico na microestrutura e propiredades mecânicas do aço AISI D6

Abstract

Several studies have demonstrated that cryogenic treatment improves the properties of tool steels by reducing the percentage of residual austenite and promoting the precipitation of ultrafine carbides, providing improvements in dimensional stability, toughness gain, mechanical strength and wear. However, the literature does not discuss clearly and sufficiently the influence of cryogenic time on the morphological change of the carbides and on the percentage dissolution of the retained austenite, and its influence on the mechanical properties of this alloy in a significant way. In this study the samples of the AISI D6 steel were characterized by spectrometry, submitted to heat treatment of tempering in a vacuum oven, the heat treatment of tempering prior to the cryogenic process was also carried out in a vacuum oven, the postventions after cryogenics were given in Mufla oven. Different times of immersion in liquid nitrogen, 2 and 24 hours were carried out in deep cryogenics in order to evaluate variances in the properties that directly influence the applicability in high yield of the cutting machetes of sheet metal. It was observed through the techniques of optical microscopy; MEV / EDS; DRX; Microhardness HV and Charpy Impact tests showed that the austenitization temperature plays a fundamental role in the cryogenics, revealing that the cryogenic treatment affects the martensite formed in the tempering (primary martensite) and not in the martensite formed from the AR transformation. immersion time in deep cryogenics has little influence on the specific properties proposed by the study, unlike the austenitizing temperature, point east, key for the purpose of application of AISI D6 steel to high performance machetes in the cutting of sheet metal.