A STATISTICAL INVESTIGATION OF CLEAVAGE MICROCRACK FORMATION IN POLYCRYSTALLINE IRON.
STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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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.
- Properties of Metals and Alloys