Fracture Toughness

The fracture toughness of engineered materials allows designers to determine the effects of pre-existing defects on the mechanical response of these materials. Plane strain fracture toughness tests were conducted in accordance with ASTM E399 using compact tension specimens. Seven (7) PM steels, including elemental, prealloyed and infiltrated grades containing 0.5 and 0.8% carbon were evaluated in the as-sintered and heat-treated condition. Densities varied from 6.6 to 7.4 g/cm3; the fracture toughness values reported here are considered valid over this density range. A specimen thickness of 0.75 inch (19 mm) or 1.00 inch (25.4 mm) was selected to ensure the test results satisfied the validity requirements of the test standard.