Predicting of atmospheric corrosivity and durability of structural materials. Part II. Impact of urban traffic pollution

The results of the atmospheric corrosivity assessment in the immediate vicinity of streets of different traffic volume in Warsaw, Krakow and Katowice are derived . On the bases of annual exposures in 2014–2018 years an equation describing the impact of environmental parameters and street traffic volume on corrosion losses of zinc and zinc coating on steel was selected.

The influence of the titanium Grade 2 thermoplastic deformation on the nanoindenation properties

Pure titanium is in biotechnology a desired material due to its excellent biocompatibility and the absence of toxic elements like a vandium or aluminium. Unfortunately, in comparison to widely used Ti6Al4V alloy it has low strenght properties. Therefore, the thermoplastic deformation was used as a means to improve its mechanical properties by the grain fragmentation. An experiment of samples compression in hightened temperature and various strain rates was conducted. The stress-strain curves and microstructure observations were made. Both indicated grain reduction. In the next step nanoindentation hardness and Young modulus measurments were made. The results indicate slight increase in hardness and stiffness in most cases. For the high strain rates a decrease in those values was observed.

Application of technical nitrogen during gas nitriding austenitic steels

The possibility of using technical nitrogen including 0,2% O2 for activation austenitic steels surfaces during gas nitriding were investigated. By changing mole fraction of technical nitrogen i NH3 /N2t mixture one can regulate oxygen potential of gas atmosphere during heating the steel to nitriding temperature and sometimes during nitriding process. Four representative austenitic steels were nitrided with good results at 570°C and under 450°C. New method can be alternative to regulating oxygen potential by air and allows avoiding installing of firing mechanism and safety control.

Phase transitions in the Fe/NH3/H2 and Fe-N systems

In the article, based on the literature, the phase changes in iron nitrides on iron powders and on solid samples were discussed. Phase transformations in NH3/H2 atmosphere and in inert atmospheres are discussed. The similarity of phase transformations in different atmospheres used during annealing were indicated. The conditions of phase transformations in iron nitrides during annealing in NH3/H2 atmosphere, argon and vacuum were discussed. Phase transformations occurring during annealing in the NH3/H2 atmosphere are reversible and there is a hysteresis phenomenon. During the phase transformation ɛγ' in the NH3/H2 atmosphere until the transformation is completed, nitrogen emission to the atmosphere takes place. On the other hand, the condition for the course of the transformation of γ'ɛ is the nitrogen flow from the atmosphere to the surface. Phase changes during heating in vacuum and argon are irreversible. During continuous heating at a rate of 30 K / min in vacuum and argon, nitrided iron powders, two phase transformations may occur, which are not accompanied by weight loss, the first (α+γ')γN in the temperature range 540÷550°C in a vacuum and 620÷630°C in argon and the second (γ+γ')ɛ in the range of 610÷620°C in vacuum and 690÷710°C in argon. In the case of heating in argon, the onset of weight loss was recorded at a temperature of about 860°C. Whereas in vacuum the denitration of nitrogen austenite γN ends at this temperature. During annealing at the temperature of 360°C, the phase change ɛγ′ in the ɛ/γ′ layer is accompanied by an increase in the thickness of the γ′ phase, which is at the expense of the thickness of the ɛ zone, while the total thickness of the layer after the transformation is the same as its initial thickness. At the temperature of 420°C, after the completion of the γ′ transformation, the formed monophasic layer γ′ is thicker than the ɛ/γ′ layers in the initial state.

Predicting of atmospheric corrosivity and durability of structural materials. Part I. Industrial, urban and rural area

The possibilities of monitoring atmospheric corrosivity in Poland in the years 1991–2019 to formulate empirical dependencies of corrosion losses of metals on selected environmental parameters and to build a program for spatial distribution of environmental data and corrosion damage have been presented. Algorithms make it possible to predict atmospheric corrosivity categories for selected industrial, urban and extra-urban areas.

Calculation of the parameters of a cylinder measured by a cross-section strategy on a coordinate measuring machine

A computer program for calculating cylinder parameters was developed based on a measurement strategy of five circles arranged along the cylinder axis. The parameters calculated by the program are: cylinder diameter, axis of inclination of the cylinder axis to the reference plane, deviations from the least squares reference cylinder (LSCY), the axis passing through the centers of the outermost measurement circles. The graphics of deviation from the cylinder dimension is shown in the Auto CAD system using the script command. The developed program complements the CMM software.

A comparison of some properties of the computer controlled nitriding process versus carburizing

A comparison is presented of the nitriding and carburizing processes. Traditional gas nitriding, despite its several advantages over carburizing, has still not achieved its due popularity. The key factor is inadequate process control. An industrial-scale computerized system, employing the nitriding potential as the fundamental controlling parameter, can produce repeatable, superior nitriding results, limiting layer brittleness and enhancing usable properties. Results obtained showed that nitriding layers match carburized layers in fatigue, while exceeding them in both impact strength and wear resistance. The superiority of the computer-controlled process over traditional nitriding is illustrated by results of wear testing. The advent of controlled nitriding makes this process a viable alternative to carburizing.

Study of selected properties of the 98W-1.4Ni-0.6Fe heavy tungsten alloy

The aim of the work was to determine the density and tensile strength Rm of the sintered rod measured in selected places along its axis. The test rod with the composition of 98W-1.4Ni-0.6Fe was produced by powder metallurgy and sintering with the participation of the liquid phase. The performed measurements showed that the density of the samples depends on the place where the sample was taken from the bar and the amount of the outer layer removed by rolling. The densities of samples taken from the ends of the bar are higher than those taken from the center of the bar. The lowest density was obtained for ready-made strength samples. The performed measurements showed that for several samples the results of density and strength Rm are correlated. Gradually decreasing sample density translates into a decrease in their tensile strength. The lower density of samples from the central part of the bar can be related both to the linear shrinkage occurring during the process, as well as to the non-uniform temperature distribution in the sintering furnace space.

Non-destructive testing by the eddy current method of half-shafts after induction hardening

The non-destructive testing method with applying eddy currents carried out on drive half-shafts used in the car drive systems was described. The aim of the testing was to establish if the tested shafts were inductively hardened. At the Łukasiewicz Research Network - Institute of Precision Mechanics, the control and measurement system was designed and built to detect efficiently the martensite structure and therefore to make possible quick control of any elements. The system has been implemented at the Neapco Europe, the manufacturer of drive-shafts for the automobile industry, in Praszka, Poland.

Optimization of the structure of titanium scaffolds reproducing the concellous bone

The paper presents the scopes of examination of the cancellous bone, 3D CAD design of scaffolds of the cancellous bone and their creation with a laser beam in SLM incremental technology. The geometrical size of the scaffold and the material feature corresponding to the Young's modulus are the parameters describing the porous structure of the cancellous bone. In the statistical analysis, these values are defined as independent variables. The physical properties of the scaffold are defined by the strength parameters determined by hardness (e.g. HIT, HM, HV and are dependent variables). The REGMULT multiple regression program was used to develop the research results. However, to optimize the porous structure of the scaffold, the single-criteria optimization program SYEQL3 was used.