Abstract
The macroscopic theory of fracture as developed by Ludwick, Druidenkov and Orowan making distinction between ductile fracture and brittle fracture point out that brittle fracture results when flow curves cross the supposed brittle fracture curve, and ductile fracture results, when flow curves cross the ductile fracture curve. On this theory the initiation mechamism of brittle fracture isconsidered according to the Griffith's theory and no consideration is made on ductile deformation to fracture.
On the other hand in the microscopical study of fracture, much effort has been made to make clear the formation of crack nuclens. From many observations, several models of pile up dislocations to develop the cracks have been reported by Zener, Orowan, Stroh, Cottrell, Mott and by some other reseachers.
But these theories of two groups have been developed independently, and few attempts have been made to establish a consistent theory to combine these two thoroughly.
This paper is an experimental report of the study to make clear the relation between brittle fracture and ductile deformation to fracture, using the X-ray diffraction methods.
In the study the X-ray apparatus with back refrection devise was used, and X-ray micro beam technique was employed and improved mecro beam cameras were designed and constructed by the author.
In this way information was obtained about the heavily deformed state of the material and about the transitions of fracture mode from ductils to brittle.
As the results of the X-ray experiments thus made with the use of these comeras, measurements were made of the size of fragmentatedcrystalline particles, the misorientation between them and the dislocation density of the fractured parts and considerations were made also of fracture and ductile deformation.
