Crack Front Penetration in Transgranular Cleavage Cracking in an Iron–silicon Alloy

Based on the analysis of the crack trapping effect of cleavage ridges and penetration of crack front segments in an iron–silicon alloy, the distance between break-through points along a high-angle grain boundary is investigated. If the break-through points are close to each other, the crack trapping effect is dominant; otherwise, the grain boundary separation in break-through windows governs the front transmission process. The relationship between the overall grain boundary fracture resistance and the break-through-point distance is quite complex. The minimum grain boundary resistance is achieved when the break-through points are about 2–3 μm apart, which is also influenced by the grain boundary shear strength, the crystallographic toughness and orientation, as well as the crack front profile.