Triangular and Intergranular Fracture of Ingot Iron During Creep

Note presenting creep tests performed on coarse-grained ingot iron over a temperature range from 700 to 1350 degrees Fahrenheit to find whether the amount of grain-boundary sliding determined the fracture mode, either transgranular or intergranular. Transgranular fractures were obtained at temperatures below 800 degrees Fahrenheit and stresses above 20,000 psi. It is concluded that a vacancy-condensation mechanism is most probably responsible for high-temperature intergranular fracturing in ingot iron.