The high temperature creep and fracture behavior of 70-30 alpha-brass

Abstract

Constant stress creep tests have been carried out over a range of stresses at 324°, 413°, 503°, and 550°C. In all cases, over almost the entire creep curve, the time dependence of the true creep strain, ∈, can be described accurately as$\in = \in _0 + \in _{\rm T} (1 - e^{ - mt} ) + \dot \in _s t + \in _L e^{p(t - t_t )}$ where ∈₀ is the instantaneous strain on loading, ∈_T the transient creep strain,m a parameter relating to the rate of exhaustion of transient creep,$\dot \in _s$ the steady creep rate, ∈_L andP are tertiary creep parameters, andt _t is the time to the onset of tertiary creep. A number of relationships exist between the transient and tertiary parameters in this equation and the steady creep rate, which suggests that the same basic deformation process operates throughout almost the entire creep life. Transient creep ends after a time,t _s, such thatmt _s is a constant (≃4). Similarly, the duration of tertiary creep (t _f – t_t), wheret _f is the time to fracture, depends on the parameter,p, asp (t_f − t_t) is a constant (≃4.5). The time to fracture is found to be related to the parametersm andp asmt _s +pt _f − t_s) =constant (−12) independent of stress and temperature.