THE USE OF CHEVRON-NOTCH METHODOLOGY IN THE DETERMINATION OF FRACTURE TOUGHNESS OF HIGH STRENGTH TOOL STEELS

The experimental determination of fracture toughness of ultra high strength tool steels often presents limitations due to difficulty in producing fatigue pre-cracked specimens. The alternative methodology using chevron-notched samples allows reliable and reproductive results of KICV. The improvement of these steel types toughness is a permanent challenger due the high amount of large, hard and brittle carbide particles. Control of solidification, conformation process and heat treatments can change the morphology, distribution, size and type of carbides. Surprisingly cast specimens with large dendrite arm spacing and decomposed and spheroidized carbides showed higher fracture toughness
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