International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Tribological tests were carried out on four Ti-TiC composite samples to investigate the tribological behaviour of this alloy and the influence of sintering parameters on it. The samples were sintered by SPS using a high voltage electrical discharge. The general sintering parameters of the samples are temperature – 1100°C, heating rate – 10 °C/s, heating time – 3 min, initial pulse current – 260 A, maximum pulse current – 500 A. The different parameters are as follows: the number of pulses used for the first and fourth samples is 1000, for the second and third samples 2000; for the first and second samples a 1 electrode system was used, for the third and fourth samples a 3-electrode system. The hardness of the samples was measured using the Vickers method. The first specimen, sintered with 1000 pulses and 1 electrode system, has the highest hardness of 456.84 HV10. This is related to the fact that this sample showed the best tribological properties: the lowest friction coefficient of 0.39 and the lowest wear rate of 6.4∙10-4 mm3/Nm. It was observed that the samples sintered with 1000 pulses had lower average coefficients of friction: the average coefficients of friction of the first and fourth samples are 0.39 and 0.48 respectively, while the second and third samples are 0.54 and 0.51 respectively. The friction and wear characteristics of the first specimen, which has the best tribological properties, were compared with those of a Ti-Al-V alloy widely used in aviation. The Ti-TiC sample showed a better friction coefficient and better wear characteristics.

Phase transformations in metals have a major influence on the material behaviour in several common engineering applications. Steels exhibiting enhanced response to transformation-induced plasticity (e. g. high strength TRIP-steels for automotive production) are examples of the important role martensite formation can play. An externally stressed specimen in the process of a phase transformation may show a significant nonlinear behaviour, which is known as transformation plasticity. Even under an externally applied load stress with the corresponding equivalent stress being small in relation to the “normal” yield stress of the material, plastic deformation occurs.
An aim of a research was to determine relaxation and transformation plasticity properties of alloyed tool steel while is tempered at elevated temperatures and for different tempering duration.

The possibility of synthesizing the Ti3AlC2 and Ti2AlC MAX phases by SPS (spark-plasma sintering) consolidation of the charge obtained as a result of mechanoactivation and a charge obtained by HVED (high-voltage electric discharge) of processing titanium and aluminum powders in kerosene has been experimentally studied. The influence of the charge activation method on phase formation and physical properties of consolidated materials is shown.

An aim of a research was to determine the reasons of fracture of aluminium alloy components used for spinning of chemical fibres and to improve spinning process by selecting material with better performance.

Analysis of PowerCore automotive air filter was made and development of new alternative air filter was performed by increasing surface area of filtering material. New shape of construction of air filter was suggested by introducing double-layer filtering material. It was determined that effective surface area of the new design of air filter was increased 1.5 times comparing with the patented PowerCore item of the same size. Efficiency and strength of the new design air filter was evaluated calculating air flux rates, deformations and displacement in SolidWorks environment.

The work presents the research of permanent strain occurred when metallurgical transformations take place even under small stress applied externally lower than the yield stress of weaker phase. Four tool steel grades were tested: THG2000 (Uddeholm, Sweden), 20X13, 40X13 and 95X18 (GOST). All steel grades differ in carbon content and amount of alloying elements and behave differently when transformation plasticity occurs. This phenomenon was observed during bending test when bending stress was 100MPa and was less than 10 % of yield strength of the steel. The steel specimens were heated to 950-1050 °C temperature and then bent during air quenching. Plastic deflections were observed though all cooling process that involved martensitic transformation as well. Different effect of compression and tensile stresses on microstructure evolution during martensitic transformation was determined as both type of stresses formed in bent specimens.

The article deals with the investigation of plastic deformations of carburized medium carbon stainless steel after quenching and tempering. After carburization the specimens were heated at 1020 °C temperature and then air quenched. At the process of air quenching the specimens were bent within the temperature dropping interval approximately from 550 °C to room temperature. The bending caused tension or compression in different parts of the specimen, so interstitial distortion was formed. As the bending stress was much lower than the yield stress, the specimen didn’t bend during the first minutes of experiment, and then started bending during the martensitic transformation (transformation plasticity effect). The curved quenched specimens then were tempered at temperatures 200, 300, 400, 500, 600 and 700 °C for 1 hour and the deflection of specimen after each tempering was measured.

The results showed different influence of tension and compression on transformations occurring in steel during quenching and tempering. The tempering temperature effect on self-deformation of curved specimen was revealed.