K. Sołek

The Use of ADINA Software to Simulate Thixocasting Processes

The main purpose of work was to develop a methodology of physical and numerical simulation of the thixocasting processes. For the purpose of the studies an experiment was conducted using a GLEEBLE 3800 simulator. In this work, the GLEEBLE 3800 system was adapted for physical simulation of the processes of light metal alloy forming in the solid-liquid state. The physical simulations of thixoforming processes and characterization of thixotropic materials were supported by computer simulations using ADINA software. The numerical model of thixoforming processes was developed in order to estimate values of the rheological model parameters.

Evolution of Globular Microstructure and Rheological Properties of Stellite 21 Alloy after Heating to Semisolid State

Metal alloys can be successfully thixoformed in the partially liquid state if they display non-dendritic near-globular microstructures. The article presents the development of feedstock with such non-dendritic microstructure produced through the solid-state route of strain-induced melt-activated (SIMA) method, for a Stellite™ 21 alloy. Stellite™ alloys are a range of cobalt-chromium alloys designed for wear and corrosion resistance, currently shaped by casting, powder metallurgy or forging processes, but semisolid-state processing offers the possibility of a near-net-shaping method for these alloys. In this work, sprayformed followed by extrusion samples were heated to the temperature range at which the liquid and solid phases coexist in the material and spheroidal shape solid particles in a liquid matrix were obtained as required for semisolid processing. Microstructural investigations were carried out using scanning electron microscopy (SEM) in combination with energy-dispersive spectroscopy (EDS), with a further objective of analyzing the rheological properties of Stellite™ 21 alloy in the semisolid state, providing results to be used for identification of a processing window of temperature and viscosity ranges for thixoforming this alloy.

Characterization of thixoforming process of 100Cr6 steel

The main goal of this work is to analyze the semi-industrial process of steel thixoforming. The process was carried out using industrial equipment. This equipment consists of a heating device, industrial robots and a hydraulic press. The globular microstructure ensuring thixotropic properties was obtained using the SIMA method. It is one of the simplest and cheapest methods which could be easy applied in the case of steel alloys. In this work, the hot forged rods, commercially produced from 100Cr6 steel, were used. The first part of the work concerned the determination of the proper temperature range, for thixoforming of 100Cr6 steel. Next, some heating tests were carried out in order to obtain as uniform temperature distribution as possible. Heating process was executed using inductive heating. Microstructure analysis of heated samples reveals globular particles surrounded by liquid phase. At last, the thixoforming process was carried out using closed-die forming technique. Completely filled die cavity and good microstructure of the part show that applied process parameters were properly selected.

An analysis of HS6-5-2 steel viscosity in the semi-solid state

The main objective of this study was an analysis of the rheological properties of selected steel alloy in the semi‐solid state. A knowledge of the rheological properties of material is crucial for the numerical modeling of the shaping technology. Semi‐solid processing of metal alloys, also known as thixoforming processes, is an innovative method which has many advantages in comparison with classical metal forming and foundry processes. The most significant achievement of this particular study is the application of a viscometer which was specially designed for material tests executed at extremely high temperatures, such as the measurement of liquid or semi‐liquid steel viscosity. This paper presents the results of a rheological analysis of HS6‐5‐2 (PN SW7M) tool steel. It was performed using a rotational viscometer with a stationary external cup. The results were used for the development of mathematical models of the apparent viscosity.

Determination of Material Properties in the Semi‐Solid State Using Gleeble Simulator

This work shows that the Gleeble thermomechanical simulator can be used to carry out controlled material tests. Although originally the simulator was not designed for testing materials in the semi‐solid state, it could be adapted to such tests with only minor changes based on the construction of a special chamber for material heating and moulds for material shaping. To achieve this, a special resistance heating system was developed and installed in the Gleeble simulator. The design of a heating chamber that allows uniform heating of the material was achieved by computer simulations. The numerical model of the resistance heating developed and the results of calculations are described in detail.