A. Khakzadshahandashti, N.varahram, P. Davami,
Volume 11, Issue 2 (June 2014)
Abstract
This article examines the Weibull statistical analysis that was used for investigating the effect of melt
filtration on tensile properties and defects formed inside the casting. Forming and entrapping of double oxide films
have been explained by using the context of critical velocity of melt in the runner. SutCast software results were used
to examine the amounts of the velocity of melt as such. SEM/EDX analysis is used to observe the presence of double
oxide films in the fracture surfaces of the tensile specimens. The article goes on to propose that castings made with
foam filters with smaller pores show higher mechanical properties and reliability due to higher Weibull modulus and
fewer defects
A. Khakzadshahandashti, N. Varahram, P. Davami, M. Pirmohammadi,
Volume 16, Issue 3 (September 2019)
Abstract
The combined influence of both melt filtration and cooling rate on the microstructure features and mechanical properties of A356 cast alloy was studied. A step casting model with five different thicknesses was used to obtain different cooling rates. The effect of melt filtration was studied by using of 10 and 20 ppi ceramic foam filters in the runner. Results showed that secondary dendrite arm spacing decreased from 80 μm to 34 μm with increasing cooling rate. Use of ceramic foam filters in the runner led to the reduction of melt velocity and surface turbulence, which prevented incorporation of oxide films and air in the melt, and consequently had an overall beneficial effect on the quality of the castings. A matrix index, which is the representative of both SDAS and microporosity content, was defined to consider the simultaneous effect of melt filtration and cooling rates on UTS variations. Also, the fracture surface study of test bars cast using 10 and 20 ppi ceramic foam filters showed features associated with ductile fracture.
