Eventos Anais de eventos
COBEF 2017
Congresso Brasileiro de Engenharia de Fabricação
ANALYSIS OF FATIGUE STRENGTH OF AUSTEMPERED DUCTILE IRON WITH DIFFERENT HEAT TREATMENT
Submission Author:
Césio Túlio Alves dos Santos , RJ
Co-Authors:
Luiz Carlos Rolim Lopes, Silvana Carreiro de Oliveira, Caroline Terra Taylor, Vinicius Cardilo Campos Alves, Gláucio Fonseca, Ricardo Leal, Luciano Baracho, Éder Silva
Presenter: Césio Túlio Alves dos Santos
doi://10.26678/ABCM.COBEF2017.COF2017-0514
Abstract
Austempered ductile cast irons (ADI) have received great attention in last years because their combined tensile properties with good ductility and fracture toughness and low production cost. However, fatigue properties of these materials are less known. The aim of the present study is to compare the fatigue strength of a ductile cast iron-Cu, Ni, Mo alloy which have received three different austempering heat treatment to produce ADIs with different tensile strength level, corresponding to the ASTM A897 grades III, IV and V requirements. Fatigue tests were performed under load control and with stress ratio equal to –1 to obtain the S-N curve of the materials with and without austempering heat treatment. In addition, tests were carried out to determine tensile properties of the alloy. Also microstructural characterization was performed using a scanning electron microscope (SEM). The first group of samples was austenitized at 910°C for 60 min and austempered at 320°C for 90 min; the second and third groups were austenitized at 930°C for 120 min, and then austempered at 300°C for 40 min and at 280°C for 40 min respectively; the fourth group were the as cast alloy. Tests were performed using different levels of amplitude, determined by the material ultimate tensile strength, in uniaxial teste using a Instron machine, model 8801. From the S-N curves, it was possible to obtain the values of fatigue limits of the materials. Based on the results obtained after austempering heat treatment, it was possible to observe changes in the fatigue strength of the alloy through the behavior of the S-N curves. This behavior could be correlated to the microstructural changes resulting from the austempering heat treatments performed.
Keywords
Mechanical Properties, Fatigue Test, Fatigue Limits, ADI
