Tomasz Lipiński

Fractal Analysis of AFM Data Characterizing Strongly Isotropic and Anisotropic Surface Topography

This study discusses changes in the value of fractal parameters determined based on functions of structure S(t), generated in different directions of anisotropy of the examined surfaces. The analyzed material consisted of AFM calibration standards TGT1, PG and TGZ1 which were used as models of strongly isotropic and anisotropic surfaces. The topography of the examined surfaces was imaged by atomic force microscopy. The obtained results indicate that all surfaces can be described mathematically to identify fractal parameters in any anisotropic direction.

The Structure and Mechanical Properties of Al-7%SiMg Alloy Treated with a Homogeneous Modifier

Results of studies on the modification of Al-7%SiMg alloy with a homogeneous modifier obtained by fast cooling of homogeneous modifiers at V=200 K/s are presented in the paper. Homogeneous modifiers are additions designed for modification of the alloys from which they were obtained at 0, 7, 12 and 20% Si. The components were put into a crucible containing liquid Al-Si alloy and kept there for one minute. The effects of cooling rate and w/w concentration of the modifier in the melt on structure and tensile strength, percentage elongation, Brinell hardness, abrasive wear are illustrated graphically. The analysis of the process of hypo-eutectic Al-Si alloy modification with a homogeneous modifier obtained from treated alloy by fast cooling shows that this modifying addition affected structural,physical and mechanical properties of Al-7%SiMg alloy.

Dimensional Structure of Non-Metallic Inclusions in High-Grade Medium Carbon Steel Melted in an Electric Furnace and Subjected to Desulfurization

Non-metallic inclusions may be introduced to liquid steel from the outside, usually with charge material, or they may be produced in the metallurgical process. According to literature, if evenly distributed, non-metallic inclusions may affect the functional properties of steel, mainly its fatigue strength. The aim of this study was to determine the quantity and dimensional structure of non-metallic inclusions in high-grade medium carbon steel melted in an electric furnace and subjected to desulfurization. The experimental material consisted of semi-finished products of high-grade, medium-carbon constructional steel containing manganese, chromium, nickel, molybdenum, and boron. The levels of phosphorus and sulphur impurities did not exceed 0.02%. Billet samples were collected to determine the chemical composition, microstructure, the relative volume of non-metallic inclusions, and the size of impurities. The results were processed and presented in graphic form.

Effect of Aging on the Microstructure and the Intergranular Corrosion Resistance of X2CrNiMoN25-7-4 Duplex Stainless Steel

Stainless steels are used widely in many industries. A duplex microstructure offers a combination of advantages, including resistance to crevice and stress corrosion, reduced susceptibility to hot cracking in comparison with fully austenitic structures and excellent tensile strength. The paper discusses the effect of aging on the microstructure and corrosion resistance of X2CrNiMoN25-7-4 super duplex stainless steel. Low and predictable corrosion rate is an important parameter for steels operating in aggressive environments. Resistance to intergranular corrosion expressed by corrosion rate (mm/year) was determined in accordance with standard PN-EN ISO 3651-1. Metallographic studies were carried out to evaluate surface degradation and intergranular corrosion. The results support an evaluation of the impact that phase fraction changes caused by aging have on resistance to intergranular corrosion. The results of the corrosion analysis were used to develop mathematical models describing changes in corrosion rate over time for different phase fractions.

Mechanical Properties of AlSi9Mg Alloy with a Sodium Modifier

Al–Si alloys are among the most popular casting metals. Two-component aluminium alloys with silicon are not suitable for direct use after melting. Subject to their silicon content, Al Si alloys have a coarse-grained eutectic phase, and alloys with more than 13% Si content also feature large crystallites or β-phase needles. The β-phase is hard, but also fragile. Large crystallites are good planes of division, and they reduce the mechanical properties of alloys.In this study, the Al-9% Si alloy was refined with a sodium modifier. The modifier was added to the mould by the in-mould method. The modifiers influence on the microstructure and mechanical properties of the alloy was presented graphically. The results of the analysis indicate that the compound modifier influenced the evaluated properties of the Al-9%Si hypoeutectic alloy.

The Microstructure and Mechanical Properties of Al-7%SiMg Alloy Treated with a Exothermic Modifier Contained Na and B

Results of studies on the modification of Al-7%SiMg alloy with an exothermic modifier on base Na2B4O7 are presented in the paper. The alloy was modified in a casting mold. Its structure, tensile strength and percentage elongation were determined. The results of the study indicate that in addition to modifier quantity and the type of reducing agent applied to produce an exothermic reaction, the reactions thermal effect influences the quality of the modification process, leading to changes in the microstructure and mechanical properties of the alloy.

The Computer Analysis Shape of Reflexes Xrd on the Basis of X2CrNiMoN25-7-4 Steel@@@Komputerowa analiza kształtu refleksów XRD na przykładzie stali X2CrNiMoN25-7-4

This paper was introduced the author’s program to the analysis of the shape of XRD reflexes. The analysis was subjected results fittings of numerical models to data got during measurements. The method of the smallest squares of mistakes was used in the analysis of the fitting. The written application lets describe peak using one from popular functions. Parameters of the diffractive reflex appointed with the program let determine lattice parameters, volumetric phase participation and determine the quantity of crystallites and network distortions. KOMPUTEROWA ANALIZA KSZTAŁTU REFLEKSOW XRD NA PRZYKŁADZIE STALI X2CrNiMoN25-7-4 Pawel Szabracki, Miroslaw Bramowicz, Tomasz Lipinski Katedra Technologii Materialow i Maszyn Uniwersytet Warminsko-Mazurski w Olsztynie S l o w a k l u c z o w e: dyfrakcja rentgenowska, XRD, Pearson VII, Gauss, Cauchy.

Effect of Environment-Friendly Modification of Al-12%Si Alloy on its Structure@@@Ekologiczna Modyfikacja Stopu Al-12%Si A Jego Struktura

The paper presents the results of a study on the modification of Al-12%Si alloy with a homogeneous modifier produced by fast cooling at a rate of 100 and 200 K/s. The homogeneous modifier had the chemical composition of the modified alloy, and it contained 0, 7, 12 and 20% Si. The modifier was mixed with liquid Al-Si alloy in the crucible for one minute. The effect of cooling rate and the modifier content of alloy mass on alloy structure was determined in the study. An analysis of the modification of eutectic Al-Si alloy with a homogeneous modifier obtained by fast cooling of the treated alloy showed that the modifier affected the structure of Al-12%Si alloy.