Title: Probability of initiation and propagation of cleavage failures in spheroidized steels

Authors: B. Strnadel, E. Mazancova, K. Mazanec

Addresses: Vitkovice Steel and Engineering Works, 706 02 Ostrava, Czechoslovakia. ' Research Institute, New Metallurgical Works, 707 02 Ostrava, Czechoslovakia. ' Institute of Metal Science, Technical University, 708 33 Ostrava, Czechoslovakia

Abstract: This paper presents a procedure for quantifying the probability of cleavage failures arising and spreading in spheroidized steels, which is based on statistical analyses of the sizes of precipitated carbides. It shows how the total cleavage fracture probability varies with the stress intensity factor, the temperature, and the deformation characteristics and microstructural parameters of the examined steel. This quantification of the total probability of cleavage fracture arising has been applied for predicting the lower bound of the temperature dependence of fracture toughness. Experimental findings have been processed to yield a statistical model of cleavage fracture propagation. The probability P_ίί of the main crack being arrested is shown to depend on a parameter (χσ2y/Κ2_IC) investigation; investigation of this dependence has revealed the lowest value of this parameter at which P_ίί = 1. The role and importance of this new parameter is similar to that of the characteristic distance.

Keywords: cleavage fracture; local fracture stress; active volume; total failure probability; crack arrest probability; Poisson distribution; carbide size distribution; fracture toughness prediction; spheroidized steels; crack initiation; crack propagation; precipitated carbides; stress intensity factors; temperature; deformation; microstructure.

DOI: 10.1504/IJMPT.1990.036609

International Journal of Materials and Product Technology, 1990 Vol.5 No.1, pp.69 - 83

Published online: 05 Nov 2010 *

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