Fracture toughness of high melting point materials

Abstract

Little information has been published on the fracture toughness properties of high-melting point metals and alloys which are mainly produced in sheet or rod form requiring special testing procedures and sample geometries. Modifications of the recommendation according to ASTM E 399 and E-740 were required in order to determine fracture toughness data at room temperature for rods of Mo and Mo-alloys produced in various sizes by pm-techniques. For larger diameter bar,s disk-shaped compact tension specimens were tested, for smaller diameter rods, surface-cracked tension specimens had to be evaluated. In the latter test, during the required fatigue precracking the crack growth can be monitored to determine threshold values for fatigue crack growth prior to the fracture toughness test. The applicability, advantages and limitations of both test procedures will be discussed. © 1994, Walter de Gruyter. All rights reserved.