Analyse quantitative, par la méthode des angles dièdres de la microstructure d’un alliage déformé et recristallisé

Quantitative evaluation of deformed and recrystallized alloy structure by means dihedral angles between grains

Institut de Métallurgie, Académie des Mines et de Métallurgie, Cracovie

Abstract

Single phase alloy in equilibrium conditions can be regarded as a set of polyhedrons (grains) with dihedral angles equal 120°. During cold plastic working their value gradually changes. Thus variance of dihedral angles may serve as a measure of deformation degree, deviation from equilibrium and also as a measure of structure inhomogeneity.

Duwalian [3] determined the relation between the variance of dihedral angles D²([math]) and the variance of planar angles D²(ᵞ) which can be measured from metallographic microsection. Assuming that the mean value of dihedral angle is equal 1200 the above relation can be expressed a following way:

[math]

Experimental part of this work, as the continuation of investigations presented during last polish-french colloquium [5] was performed using the same samples of Armco iron.

The mean values and distributions of planar angles were determined and variances of dihedral angles were calculated after different degrees of cold deformation and also after recristallisation.

The statistical analysis confirms the initial assumption that the increase of dihedral angle variance D²([math]) is due to the increament of deformation degree and the recristallisation results in descrease of its value.

Obtained results indicate that there exists positive correlation between orientation degree of intergranular surfaces, proposed by Saltykov [5], and the variance of dihedral angles.