In the cold rolling process, the expansion and coalescence of micro‐defects can make steel sheet quality descend and create edge crack in the steel sheet. And the edge crack can cause the strip rupture completely. In this research, the cohesive zone model (CZM) was used to analyse the initiation and propagation of edge crack in the cold rolling process with the non‐reversing two‐high mill. A bi‐linear traction–separation law was utilized which is primarily given by the CZM parameters including the cohesive stress, T, and the cohesive energy, Γ. Compared with other popular models such as the Gurson–Tvergaard–Needleman (GTN) model, the CZM presents certain advantages because it requires a smaller number of parameters to be defined. Comparison results of the experiments and simulation illustrated that the CZM can provide accurate prediction for the propagation of edge crack in the cold rolling process. Parametric analysis was carried out and showed that the extent of the crack propagation increases with the increasing of the reduction ratio.

A B S T R A C T The maximum crack opening displacement is introduced to investigate the effect of compressive loads on crack opening stress in tension-compression loading cycles. Based on elastic-plastic finite element analysis of centre cracked finite plate and accounting for the effects of crack geometry size, Young's modulus, yield stress and strain hardening, the explicit expression of crack opening stress versus maximum crack opening displacement is presented. This model considers the effect of compressive loads on crack opening stress and avoids adopting fracture parameters around crack tip. Besides, it could be applied in a wide range of materials and load conditions. Further studies show that experimental results of da/dN À ΔK curves with negative stress ratios could be condensed to a single curve using this crack opening stress model.Keywords compressive load effect; crack opening stress; finite element analysis; maximum crack opening displacement; tension-compression loading. N O M E N C L A T U R Ea = initial half crack length E = Young's modulus k = slope K max = maximum stress intensity factor K op = crack opening stress intensity factor L = half-length of plate L e = the smallest element size in crack tip n = strain-hardening exponent of material R = stress ratio, R = σ min /σ max r y = crack-tip plastic zone size r p = crack-tip forward plastic zone size u max = maximum crack opening displacement corresponding to σ max (MCOD) u min = maxmum crack opening displacement corresponding to σ min W = half-width of plate ΔK eff = effective stress intensity factor range ΔK = stress intensity factor range Δu = variable quantity of maximum crack opening displacement (VMCOD) σ op = crack opening stress (COS) σ s = yield stress σ max = maximum stress in the cyclic tensile load, which is positive σ min = minimum stress in the cyclic tensile load, which is negative σ op_0 = crack opening stress when the remote applied minimum stress is zero ν = Poisson's ratioCorrespondence: Y. Huang.