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The fracture toughness of a ultrahigh carbon steel containing 1.5 wt% C
Author(s) -
FERNÁNDEZVICENTE A.,
CARSÍ M.,
PEÑALBA F.,
RUANO O. A.
Publication year - 2006
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.2006.01007.x
Subject(s) - materials science , eutectic system , austenite , pearlite , microstructure , fracture toughness , metallurgy , carbide , ferrite (magnet) , grain size , toughness , composite material
Thermomechanical processing of ultrahigh‐carbon steels allows the attainment of spheroidized and pearlitic microstructures that show very different mechanical properties. Spheroidized microstructures are formed by proeutectoid and eutectoid carbide particles embedded in a ferrite matrix. The mean proeutectoid carbide particle size is larger than the mean eutectoid carbide particle size and is practically invariable with austenitizing temperature below 850 °C. Pearlitic microstructures exhibit prior austenite grain sizes and pearlite colony sizes which increase and interlamellar spacings which decrease as the austenitizing temperature increases above 850 °C. A proeutectoid carbide size distribution that remains basically constant with austenitizing temperature is also observed in these microstructures. Plane‐strain fracture toughness of spheroidized and pearlitic UHCS‐1.5C materials do not vary significantly with austenitizing temperature, being the average fracture toughness of about 40 MPa m 1/2 and 30 MPa m 1/2 , respectively. The constancy of fracture toughness with austenitizing temperature of the spheroidized microstructures is attributed to the constancy of the mean proeutectoid and eutectoid carbide size. Austenite grain size, pearlite colony size, interlamellar spacing and undissolved proeutectoid carbide size are evaluated for the influence of fracture toughness associated with pearlitic microstructures. It is found that proeutectoid carbide is the microstructural parameter that controls fracture toughness of pearlitic microstructures. Austenite grain size, pearlite colony size and interlamellar spacing are considered to have a minor influence.