Z. Rdzawski

Additives and thermal treatment influence on microstructure of nonferrous alloys

Although Zn alloys are a very widely used material, there is a need for investigations concerning the influence of thermal conditions on its microstructure and its properties, which makes it useful for the specific tasks it has to fulfil for mass-produced items manufactured by the metalworking industry, in the automotive industry, as well as in countless electronic components. One of the possibilities is to create finer microstructures and enhance their properties, to change their chemical composition by adding alloying additives, and inoculation using modifiers. So in this paper, investigation results are presented concerning the influence of chosen alloying additives, such as Sr, Ce and Ti–B on the measured and calculated thermal characteristics and microstructure of zinc alloys with the addition of aluminium and copper. Based on the results on the phase and chemical composition of the cast Zn–Al–Cu alloys, inoculated with Sr and Ti–B, no differences were detected in the phase composition of the investigated alloys, owing to changes in cooling rates, which were chosen for the sample cooling process. A small amount of added cerium caused the occurrence of new phases present in the microstructure. Modification of the Zn–Al–Cu alloy precipitates changes in the thermomorphology of the phase and the ‘tweed’ type changes in the microstructure. Moreover, the addition of cerium causes a decrease in the temperature at the beginning (TL) and the end of the solidification, as well as the occurrence of a multicomponent eutectic, which can be detected on the derivative curve.

Ultrafine Grained Copper Alloys Processed by Continuous Repetitive Corrugation and Straightening Method

A growing trend to use new copper-based functional materials is observed recently world-wide. Within this group of materials particular attention is drawn to those with ultrafine grain size of a copper matrix. This study was aimed to investigate mechanical properties, electrical conductivity and microstructure in strips of precipitation strengthened copper alloys processed by continuous repetitive corrugation and straightening (CRCS). Tests were performed with the copper alloy strips using original die set construction installed on tensile testing machine. The microstructure was investigated using optical and electron microscopy (TEM and SEM equipped with EBSD). Proposition of semi industrial application of this method have been also presented. The CRCS process effectively reduced the grain size of a copper alloy strips, demonstrating the CRCS as a promising new method for producing ultra fine grained metallic strips.

Effect of plastic deformation on the structure and texture of CuSn6 alloy

This paper presents the results of study in the structure and texture CuSn6 alloy deformed in the RCS (repetitive corrugation and straightening) process. Investigated the influence of process parameters on the above property. The obtained results were correlated with the results of the alloy subjected to cold rolling.

Effect of Re addition on the crystallization, heat treatment and structure of the Cu–Ni–Si-Cr alloy

For determination of the structure and properties of those alloys, the following investigations were carried out: scanning microscopy and EDS X-ray analysis. Investigations concerning the optimal chemical composition and production method of Cu–Ni–Si alloys modified by Cr and Re as well as the improved properties in comparison with traditional alloys contribute to better understanding of mechanisms influencing the improvement of mechanical properties of the newly developed alloys. Thermal analysis of the crystallization process allows for accurate calculation of latent heat of various phases developed during solidification. Based on the assumption that the latent crystallization heat is proportional to the share of various phases in the alloy, the thermo-derivative analysis also allows the calculation of the amount of crystallized phases. Calculation of the properties as mentioned earlier is based on the characteristic points determined in a derivative curve. The adequately selected chemical composition of the alloy, as well as the appropriate cooling rate and heat treatment conditions, leads to improvement of functional properties of manufactured elements. For the analysed alloys, a thermal derivative analysis was used to determine the kinetics of crystallization and the temperature of the beginning and the end of a phase and eutectic crystallization, mainly the liquidus temperature (TL) and solidus temperature (TSOL). The TSOL temperature determined on thermal derivative analysis is the upper limit of supersaturation of the tested alloys. The conductivity and microhardness of the tested alloys were also measured in the function of the chemical composition and the state (i.e., heat treatment).

Effect of chemical composition modification on structure and properties of the cast Zn-Al-Cu alloys

The effect of Sr, Ti-B addition on structure and properties of cast Zn-Al-Cu alloys is presented in this work. Cu as well as master alloys such as Al-Sr and Al-Ti-B were added to the zinc alloy, which was cast into a metal mould. The thermo-derivative analysis was performed using the UMSA platform (Universal Metallurgical Simulator and Analyzer) with cooling at different rates in the range from 0.09 to about 0.2 ℃ s−1. The effect was investigated of the mass concentration of alloying elements ranging from 0.1 to 1% and of the varying cooling rates on the alloys’ structure and properties, including corrosion resistance in the salt vapour environment, as well as its hardness and abrasion wear resistance in the metal-to-metal setup. Alteration of the chemical composition of the cast Zn alloys by the addition of modifiers was made to change their structure and thereby possibly improve the alloys’ properties and also the functional ones.

Effect of Continuous RCS Deformation on Microstructure and Properties of Copper and Copper Alloys Strips

The aim of this work was to study the microstructure and mechanical properties of copper, brass CuZn36 and bronze CuSn6 strips annealed and after repetitive corrugation and straightening (RCS) process. The influence of process parameters on the functional properties of strips was investigated. The study found an increase in the yield strength and tensile strength of the material after RCS process. Crystallite size measurement confirmed the presence of nanoscale structures in the studied materials after deformation by RCS process. The used method of plastic deformation is promising for development materials with improved functional properties. The paper presents also the results of numerical simulations of Cu strip after corrugation on groove and tooth rolls and next straightening. Rolling process simulations were conducted using Forge 2011® based on the finite element method.