Sains Malaysiana 44(12)(2015): 1751–1756
Microstructural Evolution and High Strain Rate Mechanical
Property
of Cobalt Superalloy Contain Titanium
(Evolusi
Mikrostruktur dan Sifat Mekanik Kadar Terikan Tinggi
Superaloi
Kobalt yang mengandungi Titanium)
TAO-HSING CHEN*
& TING-YOU CHEN
Department
of Mechanical Engineering, National Kaohsiung University of Applied Sciences,
807 Kaohsiung, Taiwan
Diserahkan: 29 September
2014/Diterima: 17 Ogos 2015
ABSTRACT
The high strain rate properties and
microstructure observations of cobalt base superalloyd contains 0.9% Ti were
investigated using Hopkinson bar. These cobalt base superalloys are tested at
strain rates of 2×103, 3×103 and
4×103 s-1 and at different temperatures (25,
500 and 900°C), respectively. It is found that the stress flow and strain rate
sensitivity increases with increasing strain rate but decrease with increasing
temperature. The microstructure observations confirm that the high strain rate
mechanical behavior of the cobalt base superalloys specimens are directly
related to the effects of the strain rate, temperature and the evolution of the
microstructural texture. The strengthening mechanism in cobalt base superalloys
is the multiplication of dislocation. The dislocation density increases with
increasing strain rate but decrease with increasing temperature.
Keywords: Cobalt superalloy;
dislocation; strain rate; Ti additions
ABSTRAK
Pemerhatian sifat kadar terikan yang
tinggi dan mikrostruktur superaloi asas kobalt yang mengandungi 0.9% Ti dikaji
dengan menggunakan bar Hopkinson. Superaloi berasaskan kobalt ini diuji pada
kadar terikan 2 × 103, 3 × 103 dan
4 × 103 s-1 dan masing-masing pada suhu yang
berbeza (25, 500 dan 900C). Adalah didapati bahawa kepekaan tegasan aliran dan
kadar terikan meningkat dengan meningkatnya kadar terikan tetapi menurun dengan
pertambahan suhu. Pemerhatian mikrostruktur mengesahkan bahawa kelakuan mekanik
kadar terikan yang tinggi oleh spesimen superaloi berasaskan kobalt berkait
rapat dengan kesan kadar terikan, suhu dan evolusi tekstur mikrostruktur.
Mekanisme pengukuhan dalam superaloi berasaskan kobalt adalah pendaraban
perkelehannya. Ketumpatan perkehelan meningkat dengan peningkatan kadar terikan
tetapi berkurangan dengan pertambahan suhu.
Kata kunci: Kadar terikan; penambahan Ti; perkelehan; superaloi
kobalt
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*Pengarang untuk surat-menyurat; email:
thchen@cc.kuas.edu.tw
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