This paper introduces a new alloying concept for low-density steels. Based on model calculations, samples—or “heats”—with 0.7 wt% C, 1.45 wt% Si, 2 wt% Cr, 0.5 wt% Ni, and an aluminium content varying from 5 to 7 wt% are prepared. The alloys are designed to obtain steel with reduced density and increased corrosion resistance suitable for products subjected to high dynamic stress during operation. Their density is in the range from 7.2 g cm−3 to 6.96 g cm−3. Basic thermophysical measurements are carried out on all the heats to determine the critical points of each phase transformation in the solid state, supported by metallographic analysis on SEM and LM or the EDS analysis of each phase. It is observed that even at very high austenitisation temperatures of 1100 °C, it is not possible to change the two-phase structure of ferrite and austenite. A substantial part of the austenite is transformed into martensite during cooling at 50 °C s−1. The carbide kappa phase is segregated at lower cooling rates (around 2.5 °C s−1).

The microstructure, mechanical, tribological, and corrosion properties of Fe–Cr–Al–Y-based oxide-precipitation-hardened (OPH) alloy at room temperature are presented. Two OPH alloys with a composition of 0.72Fe–0.15Cr–0.06Al–0.03Mo–0.01Ta–0.02Y2O3 and 0.03Y2O3 (wt.%) were prepared by mechanical alloying with different milling times. After consolidation by hot rolling, the alloys presented a very fine microstructure with a grain size of approximately 180 nm. Such a structure is relatively brittle, and its mechanical properties are enhanced by heat treatment. Annealing was performed at three temperatures (1000 °C, 1100 °C, and 1200 °C), with a holding time from 1 to 20 h. Tensile testing, wear testing, and corrosion testing were performed to evaluate the effect of heat treatment on the behavior and microstructural properties. The grain size increased almost 10 times by heat treatment, which influenced the mechanical properties. The ultimate tensile strength increased up to 300% more compared to the initial state. On the other hand, heat treatment has a negative effect on corrosion and wear resistance.

This work aimed to characterise microstructure and mechanical properties of polymer composite samples. The main task was to adapt the well-known techniques of metallography (i.e. sample preparation and microscopic examination) to documentation of multi-component polymer materials and to optimize the methods of light and electron microscopy for this particular purpose. There were several issues (e.g. low melting point, absence of electrical conductivity), which made the process different from metal samples preparation and observation and which needed to be addressed. Various mounting resins were tested for the samples to find the suitable one, then the process of grinding and polishing was optimized and finally the microstructure was documented using light and scanning electron microscopy (SEM). Samples in the undeformed state were examined as well as the samples subjected to tensile test at different temperatures. Prior to the microscopic observations the material was analysed using methods of thermal analysis (TG A, DSC) and infrared spectroscopy (FT-IR). The tensile tests were employed not only to determine the mechanical properties but also to obtain deformed samples for further microscopic observation.

The aim of this paper is to evaluate the influence of small variations in chemical composition on the corrosion resistance and mechanical properties of low-manganese and medium manganese high strength steels. Six different steels with manganese content varying from 1.5 to 4.0 wt.% and aluminium from 0.008 to 6.5 wt.% were subjected to the analysis. The other subjects for evaluation included the effect of aluminium as a replacement for silicon, niobium microalloying and the effect of heat treatment. The effect of non-metallic inclusions on localized corrosion initiation and propagation was also documented. Using potentiodynamic testing, exposure testing, tensile and impact testing, it was found that the improvement in corrosion resistance associated with increasing aluminium content is accompanied by a significant deterioration of the mechanical properties. Niobium microalloying and heat treatment was found to have no quantifiable impact on the anti-corrosion properties. The effect of aluminium content proved to be superior to the effect of nonmetallic inclusions in terms of determining the overall corrosion resistance of the experimental steels.

The wear resistant Mo coatings were deposited using SmartArc Electric Arc Wire Spray System and advanced SinplexPro high throughput atmospheric plasma spray gun. The coatings were analyzed in terms of microstructure, mechanical properties and tribological characteristics, including wear rate and wear mechanism. It was shown that despite of the differences in deposition process principles, the properties of the coatings don’t differ with respect to their functional properties. Both coatings reached comparable hardness, microhardness, wear resistance and coefficient of friction. The economic aspects remain the main argument for the recommendation of the most suitable thermal spray deposition technique for the application of molybdenum coatings.