Papers by Keyword: Casting Alloy

Abstract: The porosity is unwanted phenomenon mostly that is tried to eliminate. The pores are initiation site of fatigue fractions usually, they worse strength and ductility of materials, quality of machined surfaces and their following surface treatment.

Abstract: The effects of Mn and Ca contents on the microstructure and mechanical properties in Al-Mg alloy were investigated. The results showed that mechanical properties of Al-4.5wt.%Mg were increased as Mn content was raised from 0.1 to 0.5wt.%. Thermodynamic analysis and FE-SEM observation showed that Al₁₅(Fe,Mn)₃Si₂ phase began to form as Mn content exceeded 0.3wt.%. The case of Ca addition, the tensile strength and elongation of Al-4.5wt.%Mg were decreased as Ca content was increased from 0 to 3wt.%. The maximum solubility of Ca for Al is very lower to 0.074wt.%, the most of Ca precipitated in the form of Al₂Ca phase which is very brittle and the increase of Ca content was reduced the mechanical properties.

Abstract: The aim of the paper is to present the possibilities of computational simulations for the casting of aluminum matrix composite (AlMMC) reinforced with ceramics based on experimental data. The comparison of simulation and experimental results concerned the solidification process i.e. the course of solidification, temperature distribution and final arrangement of reinforcement particles. First, we have performed the experimental gravity casting of the aluminum matrix alloy AK12 (AlSi12CuNiMg2) and the composites AK12/SiC and AK12/C_g reinforced with silicon carbide SiC and glass carbon Cg, respectively, into the sand mold. During the experiment we have recorded the temperature using the ThermaCAM photometer system as well as in the selected point inside the sand mold. Using experimental data we have carried out the numerical calculations according to the methods and procedures contained in the program ANSYS Fluent 13. We have based the simulations on the two-dimensional model in which the Volume of Fluid (VOF) and enthalpy methods have been applied. The former is to describe two-phase system (air-composite matrix free surface, volume fraction of particular continuous phase) and the latter shows modeling of the solidification process of the alloy and composite matrix. We have used the Discrete Phase Model (DPM) to depict the presence of reinforcement particles. The assumption of the appropriate values of simulation parameters has shown that the simulation results are convergent with experimental ones. We have observed a similar course of the composite solidification (temperature change at the designated point), the temperature distribution and the arrangement of reinforcement particles for the simulation and experiment.

Abstract: This study investigates the effect of rare earth and aluminium composite modification on the structural variations of as-cast and heat treated medium carbon Fe–B cast alloys. The as-cast microstructure of Fe–B cast alloy consists of the eutectic boride, pearlite, martensite and ferrite. Moreover, compared to a netlike distribution of the coarse eutectic borides in the unmodified alloy, the eutectic boride structures in the modified alloy are greatly refined and less interconnected. After heat treatment, the phases in Fe–B cast alloy consist of the boride and martensite. The addition of rare earth helps to increase the number of the rod-shaped and round borides in Fe-B cast alloy during austenitizing. Compared to the unmodified alloy, the boride volume fraction and Rockwell hardness of the modified alloy have no significant change, however, the average area of each boride in the modified alloy is lower and the impact toughness is higher.

Abstract: The heat treatment effect of a cast shape memory alloy (SMA) from self-propagating high temperature synthesis (SHS) ingot was investigated. The composition of SHS ingot was Ti-50.8at%Ni. DSC and Tensile test specimens were cast by lost-wax process from SHS ingot. The heat treatment conditions were 400°C-60min., 500°C-60min. and 600°C-60min. for DSC and 400°C-60min. and 500°C-60min. for tensile test. Transformation temperatures were measured by differential scanning calorimetry (DSC). Mechanical properties were measured by a tensile test at several temperatures. The effects of heat treatment temperatures were same as a general TiNi wire material.