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A. Śmiglewicz, M. Jabłońska, W. Moćko, K. Kowalczyk and E. Hadasik

Abstract

The paper presents the results of investigation on X30MnAlSi26-4-3 austenitic steel subjected to dynamic compression using the split Hopkinson pressure bar. The strain rate was 3700 s−1. The compression test was also carried out without the use of breaking rings and then true strain was about 0.3. The split Hopkinson pressure bar test take only few milliseconds to complete during which time it is impossible to transfer the excess heat out of the specimen, therefore the test must be carried out in adiabatic conditions and so the increase of the temperature caused by the work of plastic deformation had to be calculated. The stepping load method was used in order to evaluate the effect of adiabatic heating on the properties of steel which allowed to maintain the isothermal deformation conditions. The paper presents the comparison of results obtained during deformation under adiabatic and isothermal conditions in correlation to structure changes occurring in course of dynamic compression.

Open access

Z. Zimniak

Abstract

This paper presents the application of the electromagnetic field as a tool for metal sheet cutting. The experiments showed that one can easily adapt the conventional cutting equipment to the electromagnetic cutting technology and thereby eliminate the mechanical work of the punch and the press. Two methods exploiting the electromagnetic field as the tool for cutting sheet metal were used. In one of the methods the cutting element was a die while in the other method a punch was used for cutting. Owing to the high quality surface of the cut obtained by each of the methods the cutting process does not entail additional costs for removing burrs. The shape of the surface of the cut is different than the one obtained by traditional blanking – no zones characteristic of the latter are present here. In the case of both materials, the rollover of the sheet surface is much larger and longer than in the conventional method. In comparison with the conventional method, the electromagnetic machining technology ensures high quality of the surface of the cut and can be successfully used in the industry.

Open access

A. Dębski, B. Onderka, W. Gąsior and T. Gancarz

Abstract

With the use of the differential thermal analysis (DTA), studies of the phase transitions were conducted for 90 of alloys from the quaternary Bi-In-Sn-Zn system and for the constant ratio of Bi:In and Bi:Sn. The studies were conducted for the alloys prepared from the purity metals (Bi, In, Sn, Zn = 99.999 mas. %) by way of melting in a graphite crucible in a glove-box filled with Ar, in which the impurities level was less than 0.1 ppm. After melting and thorough mixing, the liquid alloys were poured out into a graphite test mold. The phase transition temperature data obtained from the DTA investigations were next confronted with those determined from the calculations based on the binary and ternary optimized thermodynamic parameters available in the literature. It was found that the experimental and the calculated phase transition temperatures were in good agreement.

Open access

A.N. Wieczorek

Abstract

This paper presents the results of wear tests of shot-peened and not shot-peened cast steels used in the mining machinery industry, in particular in the construction of chain drums for armoured face conveyors. Wear tests were carried out in the conditions corresponding to the real operating conditions of armoured face conveyors during drifting work in rocks such as sandstone. The operating factors subjected to the analyses included the presence of quartz abrasive and the impact of external dynamic forces. On the basis of the wear tests as well as the microhardness and microstructure examinations performed, it has been found that the action of an additional dynamic force has a synergistic impact on the process of abrasive wear in loose quartz abrasive. It has been further found that the value of abrasive wear of chain wheels operated in the conditions of a combined action of abrasive and a dynamic force depends on whether the area of mating of wheels with the chain was shot-peened or not before the wear tests – an increase in the abrasive wear was observed for the wheels made of cast steel subjected to shot peening in the area of mating with the chain. Lower resistance to abrasive wear of the cast steels subjected to shot peening before the wear tests could result from the formation of cracks in the surface layer caused by the action of shot.

Open access

J. Roemer, L. Pieczonka, M. Juszczyk and T. Uhl

Abstract

The paper presents an application of laser spot thermography for damage detection in ceramic samples with surface breaking cracks. The measurement technique is an active thermographic approach based on an external heat delivery to a test sample, by means of a laser pulse, and signal acquisition by an infrared camera. Damage detection is based on the analysis of surface temperature distribution near the exciting laser spot. The technique is nondestructive, non-contact and allows for full-field measurements. Surface breaking cracks are a very common type of damage in ceramic materials that are introduced in the manufacturing process or during the service period. This paper briefly discusses theoretical background of laser spot thermography, describes the experimental test rig and signal processing methods involved. Damage detection results obtained with laser spot thermography are compared with reference measurements obtained with vibrothermography. This is a different modality of active thermography, that has been previously proven effective for this type of damage. We demonstrate that both measurement techniques can be effectively used for damage detection and quality control applications of ceramic materials.

Open access

K. Górecki, P. Bała, T. Kozieł and G. Cios

Abstract

In this paper findings regarding the design and synthesis of High-Entropy Alloys based on mixing enthalpy, mixing entropy, δ parameter, Ω parameter and valence electron concentration are presented. Four alloys were synthesised with different predicted crystalline structures. Results of the microstructure and crystal structure studies are presented. It was shown that predicted structures as well as complex intermetallic phases exist in the material. The validity of valence electron concentration as well as additional parameters such as mixing enthalpy, mixing entropy and others necessary to obtain only the solid solution in High-Entropy Alloys were examined.

Open access

M. Dudek-Burlikowska

Abstract

The possibility of use of Failure Mode and Effect Analysis methods is connected with continuous quality improvement of production processes in companies. Interdependence of the quality research methods and production process’s requirements have been taken into account. FMEA method is the analysis aimed at the disclosure and elimination of potential weaknesses of the process, that is the variants that may cause defects during its implementation. The example of implementing Failure Mode and Effect Analysis in polish companies have been presented.

Open access

A. Białobrzeski, J. Pezda and A. Jarco

Abstract

The present work discusses results of preliminary tests concerning the technology of continuous dosage of sodium to a metallic bath from the aspect of modification of EN AC-44200 alloy, through the use of a multiple compound (salt) of sodium. The technology consists in continuous electrolysis of sodium salts occurring directly in a crucible with liquid alloy. As a measure of the degree of alloy modification over the course of testing, the ultimate tensile strength (UTS or Rm) and analysis of microstructure are taken, which confirm the obtained effects of the modification on the investigated alloy. Assurance of stable parameters during the process of continuous modification with sodium, taking into consideration the fact of complex physical-chemical phenomena, requires additional tests aimed at their optimization and determination of a possibility of implementation of such technology in metallurgical processes.

Open access

Attila Csighy, András Koris and Gyula Vatai

Abstract

Milk and dairy products contain a number of biologically active compounds (proteins, lipids, vitamins and minerals) that are essential for human nutrition. The most common procedures for demineralization are based on ion exchange-, nanofiltration- and electrodialysis-based technologies. In this study, the application of membrane filtration-based partial demineralization of cow milk was investigated and the process modelled. Using design equations, the partial demineralization process was designed and the economy of the process calculated. The modelling and simulation of the partial demineralization process was carried out by the SuperPro Designer programme. As the first step the unit operations of the demineralization technology were defined using the tools of the programme. The SuperPro Designer possesses industrial tools with reactor models, chemical components, a database of mixtures, and price estimations. By analysing the influence of the operation parameters, the feasibility of the proposed process was investigated. From the results of the modelling it can be concluded that the partial demineralization process can be successfully implemented, achieving the expected demineralization rates with a relatively good payback time of two years.

Open access

Z. Ebrahimi

Abstract

We have utilized a phase-field model to investigate the evolution of eutectic silicon in Al-Si alloy. The interfacial fluctuations are included into a phase-field model of two-phase solidification, as stochastic noise terms and their dominant role in eutectic silicon formation is discussed. We have observed that silicon spherical particles nucleate on the foundation of primary aluminum phase and their nucleation continues on concentric rings, through the Al matrix. The nucleation of silicon particles is attributed to the inclusion of fluctuations into the phase-field equations. The simulation results have shown needle-like, fish-bone like and flakes of silicon phase by adjusting the noise coefficients to larger values. Moreover, the role of primary Al phase on nucleation of silicon particles in Al-Si alloy is elaborated. We have found that the addition of fluctuations plays the role of modifiers in our simulations and is essential for phase-field modeling of eutectic growth in Al-Si system. The simulated finger-like Al phases and spherical Si particles are very similar to those of experimental eutectic growth in modified Al-Si alloy.