Avaliação do tratamento de austêmpera em uma liga de ferro fundido nodular classe GGG50

Abstract

The purpose of this work was to verify and later demonstrate the benefits of nodular cast iron with a thermal treatment denominated austempering (ADI), with the submission of the material in specific traction tests, Impact, hardness and metallographic characterization. Both the ADI and the base material (FN) underwent the same tests so that differences could be verified after the heat treatment to modify the values of the mechanical properties of the material.Initially, the specimens were prepared from the nodular cast iron GGG 50 Class with ferritic / perlite matrix supplied by a metalworking company from the region of general fields in the form of type Y test specimens, and later half of them were heat treated. The material was chosen because of the good volume of production in the company. The parameters used were chosen because they are usually industrially used, which were the austenitization at the temperature of 900 ° C for 60 minutes and the temperature at 400 ° C for 60 minutes. The results of the tests were evaluatedcomparatively between nodular cast iron(FN) and the same in austempering condition (ADI), as well as with values found in the literature.Among the advantages are the possibilities of reducing the total time of manufacture, costs and availability of processes when compared to other material with the same mechanical properties. The austempering nodular cast iron (ADI) showed a variation in its values compared to the base material (FN), as for example the tensile strength limit values, which went from LR (FN) = 725.3 MPa to LR (ADI) = 876.1 MPa or the yield stress from LE (FN) = 436.05 MPa to LE (ADI) = 604.84 MPa. These values were obtained in laboratory tests, also showing the variation of values in the toughness, energy absorbed to the impact, hardness and elongation between the two materials. By presenting these value possibilities, this material shows its potential for a wide range of applications, either in place of conventional cast irons or forged steels that require various manufacturing processes to reach their final shape.