日本金属学会誌

J. Japan Inst. Metals, Vol. 32, No. 4 (1968),
pp. 363-368

Direct Observation of the Changes in the Dislocation Structure in a Low Carbon Steel after Tensile Deformation

Tetsu Oi1 and Kikuji Sato1

1Central Research Laboratory, Hitachi Ltd., Tokyo

Abstract:

A normalized commercial low carbon steel containing 0.24% carbon was subjected to the tensile test at strain rates (ε·) of 1.7 × 10-4, 1.0 × 10-3, 1.0 × 10-2 and 1.0 × 10-1 sec-1 for 5.0 ± 0.2% of plastic deformation (ε) to investigate the strain rate dependence of dislocation density and its distribution, and was strained at ε·=1.0 × 10-3 sec-1 for ε=20% to investigate the cell structure.
The results are as follows:
(1) The average dislocation density is 1.9 × 1010 cm-2 after 5% deformation, independent of the range of strain rates examined.
(2) The faster the strain rate, the less frequently are found grains which contain cell structures. A cell structure is found almost in every grain when ε·=1.7 × 10-4 sec-1, while only a uniform distribution of dislocations is observed when ε·=1.0 × 10-1 sec-1. At the intermediate strain rate, cell structures are observed in the grains as frequently as uniform distribution of dislocations.
(3) The cell walls are arranged into a grid-like pattern after 20% deformation, and their planes seem to correspond to one of {110}, {112} and {123} crystallographic planes.


(Received 1967/10/25)

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