400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.org SAE TECHNICAL PAPER SERIES 2004-01-1029 A Comparative Investigation on the High Temperature Fatigue of Three Cast Aluminum Alloys Carlos C. Engler-Pinto Jr., John V. Lasecki, James M. Boileau an d John E. Allison Ford Motor Company 2004 SAE World Congress Detroit, Michigan March 8-11, 2004 Downloaded from SAE International by American Univ of Beirut, Saturday, July 28, 2018All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4891Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-1615Email: Customer [email protected] ISBN 0-7680-1319-4Copyright © 2004 SAE International Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by American Univ of Beirut, Saturday, July 28, 20182004-01-1029 A Comparative Investigation on the High Temperature Fatigue of Three Cast Aluminum Alloys Carlos C. Engler-Pinto Jr., John V. Lasecki, James M. Boileau and John E. Allison Ford Motor Company Copyright © 2004 SAE International ABSTRACT The high temperature fatigue behaviors of three cast aluminum alloys used for cylinder head fabrication – 319, A356 and AS7GU – are compared under isothermal fatigue at room temperature and elevated temperatures. The thermo-mechanical fatigue behavior for both out-of- phase and in-phase loading conditions (100–300° C) has also been investigated. It has been observed that all three of these alloys present a very similar behavior under both isothermal and thermo-mechanical low-cycle fatigue. Under high-cycle fatigue, however, the alloys A356 and AS7GU exhibit superior performance. INTRODUCTION With increased competition and tougher regulations facing the automobile industry, weight reduction, higher engine performance, improved fuel economy, and reduced pollutant emissions have been targeted as key areas for future advances. Cast aluminum alloys have emerged as suitable materials to replace cast iron for the engine cylinder heads due to the high strength-to-weight ratio. To increase engine efficiency, however, the maximum operation temperature of these components has increased from approximately 170° C in earlier engines to peak temperatures well above 200° C in recent engines [1, 2]. The increase in the operational temperatures requires a material with optimized properties in terms of tensile, creep and fatigue strength. Although a number of studies have been performed on the physical metallurgy and processing of cast aluminum alloys [3-6] as well as on the fatigue properties of some aluminum alloys at room temperature [7-11], the description of the fatigue behavior of cast aluminum alloys at high temperature is not well established. Cylinder heads experience two distinct types of fatigue damage in service: low-cycle fatigue (LCF) or thermo- mechanical fatigue (TMF) resulting from engine start/stop cycles; and high-cycle fatigue (HCF) due to the variation of pressure within the combustion chamber. High-cycle fatigue originates fr