Effect of Runner Distance on Microstructure and Properties of Semi-Solid Squeeze Casting CuSn10P1 Alloy

It is easy to form reverse segregation and shrinkage porosity defects during the solidification of CuSn10P1 alloy, which leads to the poor properties and limits its application in high strength and toughness parts. In this paper, semi-solid CuSn10P1 alloy slurry was prepared by enclosed cooling slope channel (for short ECSC). The effect of runner distance on microstructure and properties by liquid squeeze casting and semi-solid squeeze casting was studied. The results showed that the microstructure of semi-solid squeeze casting is finer than that of liquid squeeze casting, and the shrinkage defects are improved. The solid fraction with 65 mm runner is lower than that without runner in liquid squeeze casting and semi-solid squeeze casting due to the retention effect of solid phase in semi-solid slurry flow, but the properties with 65 mm runner is better than that without runner. The ultimate tensile strength, yield strength and elongation of semi-solid squeeze casting CuSn10P1 alloy with 65 mm runner distance reached 466.5 MPa, 273.6 MPa and 13.4%, which were improved by 26%, 19% and 97%, respectively, as compared to that of liquid squeeze casting.

Solidification and Microstructure Simulation of A356 Aluminum Alloy Casting

To obtain an A356 aluminum alloy casting with a uniform structure and no internal shrinkage defects, ProCAST software is used to set different filling and solidification process parameters for an A356 aluminum alloy casting with large wall thickness differences, And multiple simulations are conducted to obtain optimized casting process; then, based on the process, the microstructure of the thickest and thinnest part of the casting are simulated. The size, morphology, and distribution of the simulated microstructure of the thinnest part and the thickest part of the casting are very similar. The simulated microstructure is similar to that of the actual casting. This shows that castings with uniform structure and no internal shrinkage defects can be obtained through the optimized casting process .

Minimization of Internal Shrinkage Defects in Cast Parts Using 5VA Powder Solder Application

The article presents a method for eliminating the crystallization of thermal nodes and shrinkage defects in the form of micro-friable cavities. The method of soldering on castings from steel grades VNL-1 and VNL-6 using 5VA powder solder has been investigated. Also, the optimal soldering modes were determined, the effects of soldering modes on the properties of the base material and the soldered joint were studied, the corrosion resistance was investigated, the corrosion resistance of the soldered joints in corrosive environments. The conducted studies of sealing by soldering cast parts with microdefects lead to the following results: increased corrosion resistance; ensuring increased tightness; improving the presentation; elimination of surface microdefects.

Technologies Development for Thermo-Temporal Melt Processing in Order to Improve the Quality of Metal Products

The melt thermo-temporal processing technology of using the results of analysis, which allowed to recommend it in the production of large-tonnage ingots and amorphous materials on iron, nickel and aluminum bases, was carried out. Thermo-temporal treatment of the melt leads to a favorable structure formation, decrease in its chemical and physical heterogeneity, reduction in size and number of shrinkage defects. These usually are accompanied by an increase in technological and service characteristics of alloys. The usable products suitable alloy increases, the metal consumption of products decreases.

SYSTEM ANALYSIS OF POROSITY FORMATION PROCESSES IN STEEL CASTINGS AND THEIR MATHEMATICAL MODELS

The analysis of scientific and technical information about the hardening features of steel castings, which lead to the formation of shrinkage defects is presented. The mechanisms of the relationship of the casting properties of alloys are shown. The analysis of factors that determine fluidity is carried out. The technological parameters of casting are determined, which lead to the formation of pores in steel castings. The mechanisms of porosity formation of endogenous and exogenous nature are considered. Siverts law is given, that describes the dependence of gas concentration on pressure. Graphs of changes in the concentration of nitrogen and hydrogen in the pressure range 1 - 4 atm are given for medium alloyed steel, open-hearth steel, cast iron. The mechanism of the influence of temperature and gas pressure on the process of gas evolution in the melt is analyzed. Technological methods for influencing the solubility of gases during the solidification of the casting are described. The microporosity model of Advanced Porosity Module, the Niyama criterion are analyzed. The need for further studies to develop a general model for the formation of shrinkage defects, which will take into account, inter alia, the dependence of the concentration of gases dissolved in the metal on pressure temperature, is noted.

Filtration Permeability of Dendritic Structure in Condition of Diffusion-Capillary Coalescence of Secondary Side Branches

The problem state of computer analysis of shrinkage defects in castings is analysed based on a review of theoretical and experimental studies the filtration permeability of solidifying alloys. It is shown that the use of the dimensionless permeability coefficient and its modification by introducing various corrections to the Karman-Kozeni equation, obtained for the stationary morphology of non-intersecting filtration channels, is inapplicable for the conditions of continuous change of their geometry during formation of dendrite structure. A computer model of the permeability for the mesoscale ensemble of secondary dendritic branches under the conditions of their diffusion-capillary coalescence is developed. Based on the thermodynamic apparatus and solidification modeling the influence of composition of Al-Cu-Mg alloys and heat removal velocity on the permeability coefficient under the evolution of the dendritic structure is analysed.