Effect of particle morphology on fatigue crack propagation mechanism of TiB2-reinforced steel matrix composites. (15th October 2022)

• Record Type: Journal Article
• Authors: Chen, Ronghua; Li, Bochuan; Xu, Kang
• Is Part Of: Engineering fracture mechanics. Volume 274(2022)
• Publication Date: 2022-10-15
• Subjects: Steel matrix composite -- Particle morphology -- In-situ fatigue crack propagation -- Interfacial strength; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2022.108752
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: The fatigue crack growth mechanism of as-cast and hot-rolled SMC is studied by in-situ scanning electron microscopy (SEM). The as-cast SMC has a superior fatigue crack growth resistance to hot-rolled SMC. The excellent fatigue crack growth property of as-cast SMC is dependent on TiB2 particle morphology and interfacial strength. TiB2 broken causes a decline of fatigue crack growth property at hot-rolled SMC. Abstract: Fatigue crack growth mechanisms of as-cast and hot-rolled TiB2 -reinforced steel matrix composites (SMCs) fabricated by eutectic solidification are systematically investigated through in-situ scanning electron microscopy (SEM) fatigue experiment system. The experiment results show that the as-cast SMC exhibits a relatively superior fatigue crack growth resistance with respect to the hot-rolled SMC. A lower FCGR at the low and intermediate stress intensity factor ( ΔK ) range in as-cast SMC is found, which is related to the TiB2 particle morphology. Hexagonal and rectangular primary particles have a high Young's modulus and strong interfacial bonding, which inhibits the advancing of plastic deformation in front of the crack tip. Three-dimensional interconnected eutectic particle phases composed of dendrites can produce a hardening effect at crack tip and restrain the generation of plastic deformation in this morphology region. The stress-strain field in front of the crack tip is changed by the hard TiB2 particles, which leads to the deflection of the crack path. Hence, the tortuous crack path created by facing these particles causes reduction in the effective driving force of the crack tip and slows the FCGR. The net mismatch between the surfaces lead to premature contact and roughness-induced crack closure further reducing the FCGR. In comparison, large number of hot-rolled micro-cracks in the hot-rolled SMC are detrimental to fatigue crack growth resistance through the coalesce mechanism of micro-cracks, thereby accelerating the FCGR.