Relation between Local Strain and Macroscopic Strain in Static Deformation of Plain Specimens of Isotropic Carbon Steel.

Abstract

Tensile and torsional tests were carried out on the plain specimens of isotropic carbon steels. One of the materials is an annealed cast carbon steel and the other is a rolled round carbon steel bar (S45C) which was diffusion-annealed. Fine grid lines were drawn on the surface of specimens with a diamond-point needle. The lines were fine enough not to influence the structure of the slip bands. The local strains were measured from the elongated or distorted grids. The local deformations were not uniform in either tension or torsion, and most of the local strains were not the same as the given macroscopic strain. That is, there existed various local strains which were from near zero to two or three times the given macroscopic strain. It showed the minor differences of the variation of local strains between tensile test and torsional test.