Abstract
Polycrystalline 3% silicon iron of various grain sizes has been subjected to a hydrostatic pressure of 15 kb at 293°K, and then tested in tension at atmospheric pressure in the temperature range 77°K to 383°K. The yield stress was reduced and the strain to fracture increased over temperature ranges that are dependent on the grain size. Twinning was less pronounced in pressurized material, and was also less effective in initiating cleavage fracture. The results are explained in terms of the effect of pressurization on phenomena occurring at grain boundaries.