Accession Number : AD0816973

Title :   A STATISTICAL INVESTIGATION OF CLEAVAGE MICROCRACK FORMATION IN POLYCRYSTALLINE IRON.

Descriptive Note : Technical rept.,

Corporate Author : STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Kaechele, Lloyd

Report Date : MAY 1967

Pagination or Media Count : 202

Abstract : Statistical relationships were developed by which a distribution of crack plane angles can be converted into the distribution of trace angles that will appear on the surface. The converse relationship was also developed, by which an observed distribution of surface trace angles can be converted into the true distribution of crack plane angles, between the pole of cleavage planes and the tensile axis. Simple models for microcrack formation were formulated. Predicted distributions of crack plane orientation and of surface trace angles were determined for these models and compared with the limited experimental data available. Crack formation appeared to be more biased toward planes with normals at low angles to the tensile axis than the models predicted. Tensile tests on low carbon polycrystalline iron were made at three temperatures, covering a range of stress and strain. The character of the trace angle distributions and a statistical analysis of the data led to the formulation of a stress power model, in which the number of cracks formed at a specified crack plane angle is proportional to a large (eighth to tenth) power of the normal stress across that plane.

Descriptors :   (*IRON, CRACK PROPAGATION), (*CRACK PROPAGATION, STATISTICAL ANALYSIS), CRACKS, STATISTICAL DISTRIBUTIONS, STRESSES, STRAIN(MECHANICS), CARBIDES, GRAIN BOUNDARIES, MICROSTRUCTURE, TENSILE PROPERTIES, THESES, PROBABILITY, X RAY DIFFRACTION, DISLOCATIONS, TEMPERATURE.

Subject Categories : Properties of Metals and Alloys
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE