Mechanical Properties and Fracture Toughness of AAR TC128 Grade B Steel and a Micro-Alloyed, Control-Rolled Steel, A 8XX Grade B, from -80F to +73F

摘要

Mechanical property and fracture toughness tests were conducted on two steels from -80 F to +73 F. The two steels examined were normalized and inclusion shape controlled AAR (Association of American Railroads) TC128 grade B steel and control-rolled and inclusion shape controlled A 8XX grade B steel. The tensile properties of the A 8XX steel were better than a A 8XX steel. However, the notch toughness, as determined by Charpy V-notch, NDT temperature, and J-integral tests, of the AAR TC 128 grade B steel was better than that of the A 8XX grade B steel. Unstable cleavage fracture was the predominate mode of failure of the A 8XX steel at low test temperatures. Metallographic investigations also showed that the ferrite/pearlite grain size of the AAR TC128 steel was more uniform and finer than that of the A 8XX steel.