Relationship between fracture toughness and impurity elements in Al-Zn-Mg-Cu alloys.

Abstract

A relationship between fracture toughness or critical crack tip opening displacement (CTODc) and Fe-and Si-rich insoluble inclusions in 7000 type alloys was studied. The magnitude of crack tip plastic blunting or fracture toughness is determined by forming characteristic dimples just in advance of the stretched zone. The dimples on fracture surfaces are classified into two types of populations by scanning electron micrography and energy dispersion spectroscopy analysis.zone never exceed the average spacing of these inclusions. The characteristic dimples effective to determine CTODc are formed by the inclusions containing Fe or Si.

The fatigue crack propagation behavior of the forged Mg–Zn–Y–Zr alloy

“…Generally, the dimple size depends on the inclusions or intermetallic particles size [22,23]. In the study of the crack propagation and dimple formation process, it indicated [24] that as the load applied to the specimen containing a sharp precrack increased, the inclusions near the crack tip experienced increasing strain.…”

Fracture toughness in a rolled AZ31 magnesium alloy

“…where SZH is the critical stretched zone height; λ, a constant (=2 [24]); E, Young's modulus and v, the Poisson ratio (45 GPa and 0.35 for a wrought AZ31 magnesium alloy, respectively [1]). From Eq.…”

“…In general, the dimple is mainly caused by existence of inclusions. It has been reported that the dimple size is dependent on the inclusion size [24]. The dimple size is also associated with the composition and/or content of material, because of creating different kinds of inclusions.…”

Plane-Strain Fracture Toughness on Thin AZ31 Wrought Magnesium Alloy Sheets

“…In case of aluminum alloys, it is reported that the plane-strain fracture toughness changes depending on the amount of impurities such as silicon and iron. 17) From Tables 1 and 4, it is found that the plane-strain fracture toughness increases, with decreasing the amount of ferrite, or increasing the amount of manganese. However, it is estimated that there are no relationships between fracture toughness and total amount of impurities contained in each sample.…”