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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.54  No.12 (2013)  >  pp.2195-2201

MATERIALS TRANSACTIONS
<<Previous article Vol.54  No.12 (2013)   pp.2195 - 2201 Next article>>

Effects of Hydrogen Micro Pores on Mechanical Properties in A2024 Aluminum Alloys

Hiroyuki Toda1) 2), Takaaki Inamori2), Keitaro Horikawa3), Kentaro Uesugi4), Akihisa Takeuchi4), Yoshio Suzuki4), Masakazu Kobayashi2)
1) Department of Mechanical Engineering, Graduate School of Engineering, Kyushu University 2) Department of Mechanical Engineering, Toyohashi University of Technology 3) Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University 4) Japan Synchrotron Radiation Research Institute

It has been reported that most aluminum alloys contain high-density micro pores, which make an appreciable contribution to damage evolution during ductile fracture. It is reasonable to assume that the mechanical properties of aluminum alloys are more or less improved by controlling micro pores in aluminum alloys. In the present study, the volume fraction of micro pores is controlled by controlling hydrogen content over a wide range. Tensile tests are performed using smooth and notched specimens at room and elevated temperatures, together with a fracture toughness test. It has been shown that both strength and ductility increase with decreasing micro pore volume fraction. The elimination of micro pores has pronounced effects especially on high-temperature ductility, notched tensile strength and fracture toughness. It has been observed in the in-situ observation of a room temperature tensile test that pre-existing hydrogen micro pores exhibit premature growth immediately after the onset of plastic deformation, whereas the well-known particle fracture mechanism operates only after the maximum load in the alloys with the least micro pores fraction. It can be inferred that in the notched and pre-cracked specimens, the premature growth of micro pores are driven by triaxial stress state, thereby inducing more degradation in mechanical properties.


Keyword:
aluminum alloy, hydrogen, micro pore, strength, fracture toughness, ductility, damage, computed tomography, X-ray

Received: June 27, 2013
Accepted: September 24, 2013 , Published online: November 25, 2013
Copyright © 2013 The Japan Institute of Light Metals

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