You are not logged in Total: 7journals, 20,600articles Online
Login / Register
Forgot Login?
Main menuMain menu
What's new
Journal list
Visiting ranking
Phrase ranking
About us
Journal Site
Advanced Search

Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.45  No.5 (2004)  >  pp.1706-1713

<<Previous article Vol.45  No.5 (2004)   pp.1706 - 1713 Next article>>

Tear Toughness of Permanent Mold Cast and DC Cast A356 Aluminum Alloys

Shinji Kumai1), Toshikazu Tanaka1), Hong Zhu1) and Akikazu Sato1)
1) Department of Materials Science and Engineering, Tokyo Institute of Technology

Cast products of A356 with different microstructural features were prepared; permanent-mold cast (PM) and direct-chill cast (DC) products. For each casting, a sharp notched plate specimen was subjected to static tensile loading until a crack initiated at the notch root and propagated across the width of the specimen. Both maximum load and energy to fracture (the integrated area under the load-displacement curve) increased with decreasing dendrite arm spacing (DAS). The curve of DC was smooth and the energy to fracture was quite large. The load-displacement curve was divided into two segments by a vertical line through the maximum load. The area under the first segment is a measure of the energy necessary to initiate the crack. The second segment represents the energy necessary for crack propagation. Unit energy was computed by dividing the measured energy by the net area of the specimen. Refinement of DAS and grain size increased unit energies for crack initiation (UEi) and propagation (UEp). Comparison among PM products revealed that DAS refinement was effective for increasing UEi. Among the present castings, the DC product with the finest DAS exhibited a significant increase in UEp. Observation of the crack propagation path revealed that the fracture surface was normal to the loading direction for PM. In contrast, for DC, a slanted crack path was dominant through the specimen ligament. The features of the crack propagation path are considered to have affected quantitative balance between UEi and UEp. The increased UEp in DC is considered to be due to the introduced slanted crack. Tear tests were confirmed to provide useful information concerning the effect of solidification structure on toughness, which can serve as a guide for further toughening of aluminum alloy castings.

tear toughness, A356 alloy, permanent-mold cast, direct-chill cast, unit energy, solidification structure

Received: September 30, 2003
Accepted: March 04, 2004 , Published online: June 24, 2005
Copyright (c) 2005 The Japan Institute of Light Metals



Terms of Use | Privacy Policy