1. The effect of grain size on the deformation of niobium
- Author
-
A.M Omar and A.R Entwisle
- Subjects
Materials science ,Annealing (metallurgy) ,Metallurgy ,General Engineering ,Niobium ,chemistry.chemical_element ,Thermodynamics ,Flow stress ,Oxygen ,Grain size ,chemistry ,Impurity ,Ageing ,Ultimate tensile strength - Abstract
The variation of lower yield stress with grain size has been established in niobium of two different levels of impurity. The results obey closely the Hall-Petch relationship, σy=σi + Kyd−12, with Ky⋍1.1 kg mm−32. The grain size dependence of the flow stress was found to obey a similar relationship, but with the parameter K < Ky, and increasing with strain. Niobium with ∼ 5 p.p.m. oxygen showed yield points after high temperature annealing, but was free from strain ageing effects in tensile tests above room temperature, and no recovery of yield phenomena was observed after ageing.
- Published
- 1970
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