International Journal of Materials Science and Applications
Volume 6, Issue 5, September 2017, Pages: 260-268
Received: Sep. 13, 2017;
Accepted: Sep. 22, 2017;
Published: Oct. 13, 2017
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Naoya Kanno, Materials Department, Research Laboratory, IHI Corporation, Yokohama, Japan
Yoshiki Shioda, Materials Department, Research Laboratory, IHI Corporation, Yokohama, Japan
Keiji Kubushiro, Materials Department, Research Laboratory, IHI Corporation, Yokohama, Japan
Creep rupture strength and the microstructure change during creep deformation of pre-strained Alloy263 were investigated. Creep rupture tests were conducted at 1023, 1073 K at stress range from 120 to 250 MPa. Creep strength of the pre-strained samples was higher than that of the non-strained samples. However, rupture strain of the pre-strained samples was much lower than that of non-strained samples. In the pre-strained samples, Ni3(Al, Ti)- γ’ and M23C6 inside of the grains precipitated finer than the non-strained samples compared at the same creep time. At grain boundaries, the grain boundary shielding ratio covered by M23C6 carbide showed almost same value among each samples. However, diameter of the M23C6 particle decreased in pre-strained samples. Furthermore, dynamic recrystallization was promoted and precipitation free zone (PFZ) was formed around Ni3Ti-η phase at grain boundary. These observations show that increase in creep-strength of pre-strained sample was due to increase in precipitation strengthening in the grain by fine precipitation of γ’ and M23C6. In addition, resistance against crack propagation at grain boundary increased by the fine precipitation of grain boundary M23C6 even though formation of PFZ and promotion of the dynamic recrystallization. It is estimated that Orowan-stress of pre-strained samples was 1.7 times higher than non-strained samples. It is considered that these strengthening effects overcome the weakening effects in the pre-strained samples.
Effect of Cold Work on Creep Rupture Strength of Alloy263, International Journal of Materials Science and Applications.
Vol. 6, No. 5,
2017, pp. 260-268.
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