PLANE STRAIN FRACTURE TOUGHNESS OF LARGE D6ac STEEL SPECIMENS

摘要

Altogether; eighteen 2" x 2" x 24" bars of Ladlsh D6ac rolled steel were tested in a bend test fixture to obtain a plane strain fracture toughness Index KIc One bar was used to develop a calibration curve rwsded to calculate this parameter. The other seventeen were tested to failure in bending. Of these, eight received the recommended heat treatment referred to herein as Aus-Bay, with air cooling after tempering; four received a heat treatment with no Aus-Bay and four received a heat treatment incorporating, the Aus-Eay and a furnace cool to- 500°F after second temper. The first set (Aus-Bay) had the best-fracture toughness, the third, set. was almost as fracture tough as the first- set (except for the -65*F data). and the second-set (Aus-Bay Furnace Cool) had the least fracture toughness.