Effects of Strain Rate and Temperature on Tensile Properties, Deformation and Dynamic Strain Ageing Behavior of Ni-Base Superalloy Superni 263

The paper summarizes results of tensile tests in low alloy steel (LAS) specimens (steels 15Kh2MFA and 15Kh2NMFA). Slow Strain Rate Tensile tests (SSRT) were performed in air at temperatures from 22 to 325°C over a wide range of strain rates from 2.5×10-6 to 1.67×10-3 s-1. The possible effect of strain rate and temperature to mechanical properties of tested LAS is searched for. The dynamic strain ageing (DSA) was observed within certain temperature ranges at lower strain rates tested and its hardening effect in terms of the maximum strengthening stress decreased linearly with the increase of log strain rate. It has been found that the occurrence of susceptibility to environmentally assisted cracking (EAC) of tested steels in high temperature water (HTW) is corelated to the DSA behavior. The result suggest that DSA reduces ductility of reactor pressure vessel (RPV) steel and its role in enhancing the EAC of RPV steels should not be neglected, in view of the coincidence with susceptibility zones for DSA and EAC in terms of strain rate and temperature. A reasonable coincidence was observed between the susceptibility to DSA exhibited by SSRT in air and with the EAC behavior observed in laboratory experiments.

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The effect of dynamic strain ageing on the anomalous strain-rate-dependent tensile strain of Zircaloy-4

Materials Letters ◽

10.1016/0167-577x(90)90077-y ◽

1990 ◽

Vol 9 (10) ◽

pp. 413-415 ◽

Cited By ~ 3

Author(s):

Jong Sik Ahn ◽

Soo Woo Nam

Keyword(s):

Strain Rate ◽

Tensile Strain ◽

Dynamic Strain ◽

Dynamic Strain Ageing ◽

Strain Ageing ◽

Rate Dependent

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Superplasticity in Coarse-Grained Al-Mg Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.519-521.1285 ◽

2006 ◽

Vol 519-521 ◽

pp. 1285-1290 ◽

Cited By ~ 1

Author(s):

Ehab Samuel ◽

John J. Jonas ◽

F.H. Samuel ◽

S.R. MacEwen

Keyword(s):

Flow Stress ◽

Strain Rate ◽

Mg Alloys ◽

Coarse Grained ◽

High Temperature Deformation ◽

Dynamic Strain ◽

Temperature Deformation ◽

Dynamic Strain Ageing ◽

Strain Ageing ◽

Al Mg Alloys

Superplasticity refers to a high temperature deformation process involving a marked sensitivity of the flow stress to the imposed strain rate, with resulting enhanced ductility. Although conventionally associated with fine-grained materials, superplasticity has recently been observed in coarse-grained alloys. The present research involves the deformation behavior of Al-Mg base alloys, where superpure Al-3%Mg and Al-5%Mg, and commercial Al 5056 were selected for study. The results for the Al-5%Mg and Al 5056 alloys are presented in this article. Flat sheet-type samples were tensile tested to 10% strain at increasing temperatures and at prescribed strain rates (0.001/s, 0.01/s, and 0.1/s). The dependence of flow stress on temperature was found to display some unusual characteristics. This behavior is interpreted as resulting from the occurrence of dynamic strain ageing (DSA). The aim of the overall study is to determine the relation between DSA and superplasticity in coarse-grained Al-Mg alloys. This will, in turn, lead to the control of the strain ageing behavior so as to produce the largest possible values of strain rate sensitivity (and, hence, elongation).

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