Petra Lacková

Analysis of Pearlitic Cold Drawn Steel Wire

The effect of microstructure on the mechanical properties of cord steel wires was investigated. Material properties and damage behaviours were identified. Metal cord, for reinforcing articles of an elastomeric material, such as tires, conveyor belts and so on of the single strand type, in particular made up of a plurality of 3, 4 or 6 wires, where in the said wires are twisted together loosely. The metal cord characterized by the fact that the diameter of the individual constituent wires varies between 0.12 and 0.30 mm. Rm tested cord wire was max. 2 946 MPa. Fracture surfaces cords steels were observed.

The Influence of Severe Plastic Deformation on Structure and Mechanical Properties the Aluminium Alloy EN AW 6082

The effect of severe plastic deformation by ECAP process on the microstructures and mechanical properties of the aluminium alloy EN AW 6082 produced by cold extrusion is investigated. In both states were evaluated the structural changes by light microscopy, the analysis particles in structures, by X-ray diffraction (XRD) in transmission mode by synchrotron radiation and mechanical properties. Severe plastic deformation leads to strengthening of investigated EN AW 6082 alloy but on the other hand the plasticity of ECAP-ed alloy decreases.

IMPACT OF PLASTIC DEFORMATION ON THE PROPERTIES OF A SELECTED ALUMINIUM ALLOY

This paper reports on an experiment to assess the influence of plastic deformation on the microstructure and properties of EN AW 6012 (AlMgSiPb) aluminium alloy in two states. The first was the initial state with heat treatment T3, and the second was the state after intensive plastic deformation by ECAP (Equal Channel Angular Pressing) technology. The ECAP process was carried out repeatedly at room temperature. In the initial state of the alloy, the process redistributed eutectic Si-particles and increased the strength of the alloy. The mechanical properties and the hardness increased due to intensive plastic deformation (the yield strength increased by 15%, the tensile strength by 6%, and the hardness by 23%). The fracture cracks initiated and propagated mainly along eutectic particles. The fracture area of the ECAPed specimen displayed a typical ductile cavity characteristic.

Some Possibilities of Evaluation of Corrosive Resistance of Metal and Non-Metal Coatings

The study investigated the possibilities of determination of corrosion resistance of metal and non-metal (organic) coatings deposited to steel surface in the corrosion environment. To determine the corrosion rate of metal PVD coating based on Ti, we used the method involving measurement of polarization conductivity. Corrosion resistance of galvanic Ni or Ni-Co coatings was determined by measuring free corrosion potential ESCE (against that of saturated calomel electrode SCE), or by means of potentiodynamic polarization relationships according to Tafel. These methods provided the basic corrosion characteristics: corrosion potential Ecorr, instantaneous corrosion rate jcorr and polarization resistance Rp. Corrosion resistance of organic coating Woerodur, which was applied by pressure spray to the substrate pre-treated in various ways, was tested in a salt-fog environment. After the exposure to the respective environment we evaluated the appearance of coating. The aim of the study was to point out to the availability of methods suitable for evaluation of corrosion resistance of coatings, and to the possibilities of their application under real practical conditions.

The Corrosion Characteristics of AlSi1MgMn

The paper presents the evaluation of corrosion resistance of aluminium alloy AlSi1MgMn. This alloy is used above all in any atmospheric conditions. The corrosion resistance of the alloy was evaluated by determining the open circuit potential (OCP) in solution SARS (this solution simulates the industrial atmosphere) after the 10 months of exposure time. The surface of aluminum alloys were analyzed by using energy dispersive X-ray analysis after the exposure time. The basic of corrosion characteristics (corrosion potential Ecorr, corrosion rate icorr and polarization resistance Rp) were determined by potenciodynamic measurements according to Tafel’s and Stern’s methods.

The Corrosion Properties of EN AW 7075 Aluminium Alloy in Power Industry

The study in this paper aimed on the corrosion properties of aluminium alloys used in the power industry. The corrosion characteristics were evaluated in the initial and state after severe plastic deformation of aluminium alloy AlZnMgCu. Due to the frequent interaction of fatigue failure accompanied corrosive failure (e.g. aircraft wings, turbine blades etc.) fatigue characteristics of selected alloy were evaluated. Standard corrosion characteristics such as corrosion potential, polarization resistance, corrosion rate and the corrosion products were evaluated for both states of an alloy in distilled water and SARS during exposition reaching 263 520 minutes.

Effect of Technologies Processing on Material Properties of Selected Aluminium Alloys

The paper is concerned with an analysis of utility properties of selected aluminium alloys, namely EN AW 6082 (AlSi1MgMn), EN AW 6061 (AlMg1SiCu) and EN AW 7075 (AlZn5.5MgCu) with different technology of hot processing. The alloys were hot processed to reach T3 condition (solution annealing, cold forming and natural aging) and to reach T4 condition (solution annealing and natural aging). The following parameters were subject to evaluation: microstructure and sub-structure, mechanical properties (strength and plastic characteristics stated in Table. 1) as well as fatigue properties of these alloys assessed during alternative symmetrical stress in torsion. The paper was aimed to study the affect of processing technology of three aluminium alloys on their utility properties in the conditions of tensile stress and cyclic stress in torsion.

Possibilities of Preparing Tools Working in Conditions of Abrasion Wear with the Modification of the Tool Surfaces by Nitridation

The proposed paper deals about the heat treatment of two types of chromium tool steels that are assigned to work in specific conditions of abrasion wear. The materials are heat treated to achieve high hardness for higher abrasion wear resistance. An additional increase of the materials abrasion wear resistance can be achieved by applying nitridation with diffusion annealing of the material surface. The paper deals about the influence of the material purity, his chemical composition on the process of diffusion, the quality of the nitrided layer of a vacuum smelted steel Bӧhler W400 VMR and a chromium steel X210Cr12.

Influence of the Strain Rate and Heat Treatment on the Mechanical Properties of Steel Sheets

The paper analyses the influence of the strain rate on the behaviour of unalloyed steels with Re 210 – 550 MPa in the deformation process. It presents and analyses the results of the influence of the strain rate ranging from 10-3 to 2.5.102 s-1 on the yield point, the tensile strength, the elongation and the reduction of area. It analyses the non-homogeneity of development of plastic deformation from both the macroscopic and microscopic points of view, as well as the influence of the strain rate on the development of plastic deformation. Since the intensity of the influence of the strain rate on the properties of materials depends on their internal structure, the tested steels are divided into three groups based on their yield point and yield point to tensile strength ratio.

Influence of Severe Plastic Deformation on the Properties of a Selected Aluminium Alloy

This article deals about structural, mechanical and fatigue properties of an aluminium alloy EN AW 6061 (AlMg1SiCu) reinforced with SiC particles, in the initial state and in the state after intensive plastic deformation acquired by the process ECAP (Equal Channel Angular Pressing). In both states microstructures were evaluated with metallographic procedures, mechanical properties (yield strength, ultimate tensile strength, elongation) and fatigue curve at cyclic load in torsion. The main goal of this article was to study the influence of the intensive plastic deformation on an aluminium alloy reinforced with SiC particles prepared by powder metallurgy technique.