skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

Abstract

The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)

Authors:
 [1];  [2]
  1. INFM-Dept. of 'Ingegneria dell'Innovazione', Engineering Faculty, University of Lecce, Via per Arnesano, 73100, Lecce (Italy). E-mail: pasquale.cavaliere@unile.it
  2. INFM-Dept. of 'Ingegneria dell'Innovazione', Engineering Faculty, University of Lecce, Via per Arnesano, 73100, Lecce (Italy)
Publication Date:
OSTI Identifier:
21003535
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 58; Journal Issue: 3; Other Information: DOI: 10.1016/j.matchar.2006.04.025; PII: S1044-5803(06)00130-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AGING; ASTATINE 220; CASTING; CASTINGS; HEAT TREATMENTS; MAGNESIUM ALLOYS; PRESSURE RANGE MEGA PA 10-100; SCANNING ELECTRON MICROSCOPY; THERMAL FATIGUE; THERMAL FRACTURES

Citation Formats

Cavaliere, P., and De Marco, P.P. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting. United States: N. p., 2007. Web. doi:10.1016/j.matchar.2006.04.025.
Cavaliere, P., & De Marco, P.P. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting. United States. doi:10.1016/j.matchar.2006.04.025.
Cavaliere, P., and De Marco, P.P. Thu . "Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting". United States. doi:10.1016/j.matchar.2006.04.025.
@article{osti_21003535,
title = {Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting},
author = {Cavaliere, P. and De Marco, P.P.},
abstractNote = {The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)},
doi = {10.1016/j.matchar.2006.04.025},
journal = {Materials Characterization},
number = 3,
volume = 58,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • A short study has been conducted to assess the performance of friction stir welded Mg/steel joints under dynamic loads. The major mode of failure was found to be top Mg sheet fracture. Crack initiation is noted to have taken place at the Mg/steel interface. The fatigue life of the joints is found to be significantly different than the fatigue data of the Mg alloy obtained from the literature. The reasons behind such a difference have been examined in this work.
  • Spatial variations of microstructure, hardness, chemical composition, tensile behavior, texture and residual stresses were investigated in a friction-stir-processed (FSP) AZ31B magnesium alloy. The residual stresses were measured using two different methods: neutron diffraction and the contour method. No significant variations in the hardness and chemical compositions were found in the FSP zones, including the severely deformed stir zone (SZ), which showed a finer grain size compared to the heat-affected zone and base material. On the other hand, significant changes in the tensile yield strength, texture, and residual stresses were observed in the FSP zones. The relationship between the texture variationsmore » and yield strength reduction; and its influence on the decrease in the residual stress near the SZ is discussed. Finally, the residual stresses measured by neutron diffraction and the contour method are compared and the effect of the texture on neutron diffraction residual stress measurements is discussed.« less
  • The effect of friction stir processing (FSP) on the fatigue life of a cast Al-7Si-0.6Mg alloy at a stress ratio of R=0 was evaluated. Two types of specimen geometry were used for the FSPed condition, through-thickness processed and partial thickness processed. FSP enhanced the fatigue life by a factor of 15 for the through thickness processed samples at lower stress amplitudes. This is different from the FSP specimens tested at R=-1 and similar stress amplitudes where a 5 times improvement in fatigue life was observed. In light of these observations, various closure mechanisms were examined.
  • In this paper, the authors report the first results using friction stir processing (FSP). In the last ten years, a new technique of Friction Stir Welding (FSW) has emerged as an exciting solid state joining technique for aluminum alloys. This technique, developed by The Welding Institute (TWI), involves traversing a rotating tool that produces intense plastic deformation through a stirring action. The localized heating is produced by friction between the tool shoulder and the sheet top surface, as well as plastic deformation of the material in contact with the tool. This results in a stirred zone with a very finemore » grain size in a single pass. Mahoney et al. observed a grain size of 3 {micro}m in a 7075 Al alloy. This process can be easily adopted as a processing technique to obtain fine grain size. FSP of a commercial 7075 Al alloy resulted in significant enhancement of superplastic properties. The optimum superplastic strain rate was 10{sup {minus}2}s{sup {minus}1} at 490 C in the FSP 7075 Al alloy, an improvement of more than an order of magnitude in strain rate. The present results suggest an exciting possibility to use a simple FSP technique to enhance grain size dependent properties.« less