ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Stress change experiments during compressive creep tests at high stresses on polycrystalline MgO at 1596 K have shown that the creep rate at any instant during transient and steady state creep is predicted by the ratio,r/h, wherer is the rate of recovery (=−∂σ/t6t) andh is the coefficient of strain hardening (=∂σ/∂ε). Over most of transient and steady state creep, whenh is constant and the decrease in creep rate, $$\dot \in$$ , is a direct result of a decrease inr, the variation of the creep strain,ε, with time,t, is accurately described as $$ \in = \in _0 + \in _T (1 - e^{ - mt} ) + \dot \in _s t$$ whereε 0 is the instantaneous strain on loading,ε T the transient creep strain,m relates to the rate of exhaustion of transient creep and $$\dot \in _s$$ is the steady creep rate. Deviations from this equation occur during the initial 10 to 15% of the transient creep life, whenh increases rapidly. The variations in $$\dot \in$$ ,r andh during transient and steady state creep are explained in terms of a model for creep in which the rate-determining process is the diffusion controlled growth of the three-dimensional dislocation network within subgrains to form dislocation sources allowing slip to occur.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00570377
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