INTERGRANULAR FRACTURE IN CLEAVAGE FRACTURE TEMPERATURE-RANGE

The fracture of alpha iron and C-Mn submerged arc weld metal at temper atures below the brittle-ductile transition temperature is examined. T he probability of intergranular fracture occurring in a regime where c leavage fracture is observed is considered with respect to simple theo retical arguments that take into account the geometry of grains and th e relative energy of the two fracture processes. The experimental obse rvations are examined in relation to the predictions of these argument s. Simple geometrical arguments demonstrate that a small proportion of intergranular fracture is expected to accompany cleavage fracture in most specimens of polycrystalline alpha iron and ferritic steels fract ured at temperatures below the brittle-ductile transition temperature.