Study of the fatigue lifetimes and crack propagation behaviour of a high speed steel as a function of the R value

Abstract

A B S T R A C T High speed steels, such as the alloy H-13, when used as forging dies are subjected to both wear and cyclic loading, and both of these factors can affect the useful life of such dies. It follows that it is of some importance to determine the fatigue characteristics of such steels. However, fatigue studies of such alloys are limited, especially with respect to fatigue crack propagation (FCP) behaviour as a function of mean stress, and therefore more detailed studies are necessary.In the present study, the fatigue lifetimes and the crack propagation behaviour of a high speed steel were experimentally investigated in laboratory air under different stress ratios, R. A modified linear-elastic fracture mechanics (LEFM) approach was applied to analyze the experimentally-obtained FCP behaviour. The predicted S-N curves and crack growth behaviour for a wide range of R ratios agree well with the experimental data, and the modified LEFM approach is therefore considered to be useful for evaluation of the fatigue behaviour of this class of high strength steels. A = Material-environmental constant a = Half crack length da/dN = Rate of crack propagation F = Elastic-plastic correction factor f = Stress frequency K = Stress intensity factor K T = Stress concentration factor K max = Maximum stress intensity factor K max th = Threshold maximum stress intensity factor K min = Minimum stress intensity factor K op = Crack-opening stress intensity factor K op max = Maximum crack-opening stress intensity factor K = Stress intensity factor range K eff = Effective stress intensity factor range K eff th = Threshold effective stress intensity factor range k = Material constant M = A modified linear elastic fracture mechanics parameter N = Number of cycles N f = Number of cycles to failure N/N f = Fatigue life ratio Correspondence: S. Ishihara.

Effect of Rod-like Structure on Fatigue Life, Short Surface Crack Initiation and Growth Characteristics of Extruded Aluminum Alloy A2024 (Analysis via Modified Linear Elastic Fracture Mechanics)

“…The initiation and growth characteristics of micron-sized cracks were investigated using atomic force microscopy (AFM). Furthermore, the Nf and FCG behavior were analyzed based on the MLEFM parameter M [11][12][13][14]. The analysis results agreed well with the experimental results.…”

“…lshihara et al [10] investigated the FCG properties of short cracks with a length of 20 µm or more from the fatigue process of cast aluminum alloy W319-T7. These properties were analyzed using the modified linear elastic fracture mechanics (MLEFM) parameter, M [11][12][13][14]. They reported the effectiveness of using M to analyze short fatigue crack growth behavior.…”

Requirements and Variability Affecting the Durability of Bonded Joints

“…Whilst the origin of Equation (1) can be traced back to Hartman and Schijve [33], similar equations can be found in [34][35][36][37][38][39], and its link to fractal based crack growth equations is discussed in [40,41]. A range of examples showing how this formulation can be used to study aircraft sustainment related problems are given in [40][41][42][43][44][45][46][47][48][49].…”

Crack growth: Does microstructure play a role?

“…In the derivations of similar equations, the difference lies in the form of the denominator [49,50]. Variants of equation ( 1) that relate ⁄ to (∆ − ∆ thr ) have been also developed and validated for the growth of both long and small cracks, by McEvily et al [51][52][53], as well as in [54].…”