Sains Malaysiana 48(12)(2019): 2749–2757

http://dx.doi.org/10.17576/jsm-2019-4812-16

Microstructural Refinement and Corrosion Resistance Improvement of Heat Treated A356 Alloy Processed by Equal Channel Angular Pressing

(Mikrostruktur Penghalusan dan Rintangan Kakisan Peningkatan Haba Dirawat A356 Aloi

Diproses oleh Saluran Sama Sudut Menekan)

M.A. GEBRIL^1,2*, M.Z. OMAR¹, N.K. OTHMAN³ & I.F. MOHAMED⁴

¹Centre for Materials Engineering and Smart Manufacturing, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

²Department of Mechanical Engineering, Faculty of Engineering, Benghazi University, Benghazi, Libya

³School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

⁴Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

Received: 12 June 2019/Accepted: 27 September 2019

ABSTRACT

The microstructure refinement, hardness and corrosion resistance of heat-treated A356 aluminium alloy processed by equal-channel angular pressing (ECAP) were investigated. ECAP was carried out at room temperature using a mold, with a channel angle of 120° via route A. Results of the investigation confirm that the flaky coarse silicon particles were effectively fragmented from 4.22 to 0.761 μm and the grain size reduced from 171 to 40 μm after four passes of heat-treated as-cast using ECAP process. ECAP processing increases the hardness of heat-treated as-cast alloy from 61 Hv to 125 HV after four passes. Heat-treated A356 alloy shows enhanced corrosion resistance from 0.0424 to 0.00149 mmy-1, after four passes. In this research, ECAP processing has been shown to improve the hardness and corrosion resistance of as-cast A356 alloy.

Keywords: A356 aluminium alloy; corrosion rate; ECAP; grain size; heat treatment

ABSTRAK

Penghalusan mikrostruktur, kekerasan dan rintangan kakisan aloi aluminum A356 terawat haba yang diproses secara saluran sama sudut menekan (ECAP) dikaji. ECAP dilakukan pada suhu bilik dengan menggunakan acuan yang mempunyai sudut saluran 120° melalui laluan A. Keputusan kajian mengesahkan bahawa zarah silikon kasar berkeping terserpih dengan baik daripada 4.22 kepada 0.761 μm manakala saiz butiran berkurangan daripada 171 kepada 40 μm selepas empat laluan tuang terawat haba dengan menggunakan proses ECAP. Pemprosesan ECAP meningkatkan kekerasan aloi tuang terawat haba daripada 61 Hv kepada 125 HV selepas empat laluan. Aloi A356 terawat haba menunjukkan rintangan kakisan yang lebih baik, iaitu daripada 0.0424 kepada 0.00149 mmy-1 selepas empat laluan. Kajian ini telah menunjukkan bahawa pemprosesan ECAP telah meningkatkan kekerasan dan rintangan kakisan aloi A356 tuang.

Kata kunci: Aloi aluminium A356; ECAP; kadar kakisan; rawatan haba; saiz butiran

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*Corresponding author; email: gebril.ukm@gmail.com