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.
Effect of alloy purity and aging on the fracture toughness of three type alloys has been examined to clear the relationship between the fracture toughness and tensile properties. The fracture toughness were evaluated by the critical crack tip opening displacement (CTODc) derived from stretched zone analysis. The general magnitud of CTODc increases with reduction in iron and silicon contents. The value of CTODc depends on the aging condition. It lowers as the yield strength rises, or the value of the strain-hardening exponent decreases. All underaged alloys show a superior to toughness to the overaged of ones having the same yield strength. The total impurity content is, accordingly, a dominant fractor governing the fracture toughness of these alloys. The final values of fracture toughness were also determined by the tensile parameters, yield strength and strain-hardening exponent.Keysords: 7075 aluminum alloy, fracture toughness, tensile properties, critical crack tip opening displacement, effect of purity.
To develop an improved surface treatment for producing metallic luster on magnesium alloys by controlling surface roughness, we analyzed the angle of incidence c, the instrument acceptance angle Du and the root mean square slope m, for experimental results on specular glossiness Gs and root mean square roughness s. First, we derived a theoretical equation from the theory of electromagnetic waves and a model of surface roughness, assuming that the root mean square roughness is much smaller than the wavelength of the incident radiation. In this equation, the ratio R/R 0 of the specular reflectance of the specimens to the specular reflectance of a smooth surface indicates the sum of the specular reflection component and the scattering reflection component for the instrument acceptance angle. This reflectance is a function of the angle of incidence. In this study, angles of incidence of 20°, 60°and 85°were used. Next, the specular glossiness and the root mean square roughness were measured for the surface of AZ31 magnesium alloy specimens treated with acidic aqueous solution. The value of the root mean square slope was obtained from the theoretical equation and was compared with the experimental results. We found that the experimental results matched the results calculated for an angle of incidence of 20°. These results clarified that the reflectance R/R 0 is a function of s/l, the angle of incidence c, the instrument acceptance angle Du and the root mean square slope m. These results will be useful for developing better surface treatments for producing metallic luster on magnesium alloys. ( 1 )
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.