Artur Żak

The article presents the results of hot rolling tests on a feedstock composed of S355J2 and NANOS-BA® steel layers into flat bars. The study was carried out to assess the susceptibility of the materials to create S355J2/NANOS-BA clad plates in the hot rolled bonding process. The subject of the article are the phenomena occurring during the connection of well-weldable S355J2 structural steel with ferritic-pearlitic microstructure with nano-structured, non-weldable NANOS-BA® steel with nanobainitic microstructure in the process of hot rolling and heat treatment. The microstructure and selected strength properties of high-strength clad plates are described after hot rolling with integrated inter-operational annealing at 690°C for 4 h and after additional isothermal annealing at 210°C for 120 h. As a result of hot rolled bonding process with two-stage heat treatment process a durable combination of S355J2 and NANOS-BA® steels with high mechanical properties was obtained, including: Rm>1199 MPa and A=14%, without microscopically visible cracks in the joined plane. High-strength laminated flat bars combining the features of the component layers such as high strength, ballistic and abrasive resistance, while maintaining good plasticity, weldability and relatively low production costs may be the answer to the current industry demand.

The article presents the results of controlled cooling experiments after austenitising a V36 section made of structural steel S480W. The experiments involved variable cooling intensity affecting the cross-section of the test element. The tests aimed to investigate the possibility of modifying the microstructure and uniformly increasing the mechanical properties of steel sections with varied cross-sectional wall thickness in relation to free-air cooling. The research work involved the determination of section-related cooling characteristics identified using various parameters of compressed air blown from nozzles onto selected surfaces of the section. The accelerated cooling tests led to the formation of a fine ferritic-pearlitic microstructure having ferrite grain size Dα restricted within the range of 6.8 μm to 6.5 μm. In addition, the tests resulted in the obtainment of uniform hardness distribution in cross-section, an increase in yield point Re and tensile strength Rm (restricted within the range of approximately 40 MPa to 60 MPa) while maintaining similar elongation.

Microwave Assisted Self-propagating High-temperature Synthesis (MASHS) was used to prepare open-porous MAX phase preforms in Ti-Al-C and Ti-Si-C systems, which were further used as reinforcements for Al-Si matrix composite materials. The pretreatment of substrates was investigated to obtain open-porous cellular structures. Squeeze casting infiltration was chosen to be implemented as a method of composites manufacturing. Process parameters were adjusted in order to avoid oxidation during infiltration and to ensure the proper filling. Obtained materials were reproducible, well saturated and dense, without significant residual porosity or undesired interactions between the constituents. Based on this and the previous work of the authors, the reinforcement effect was characterized and compared for both systems. For the Al-Si+Ti-Al-C composite, an approx. 4-fold increase in hardness and instrumental Young's modulus was observed in relation to the matrix material. Compared to the matrix, Al-Si+Ti-Si-C composite improved more than 5-fold in hardness and almost 6-fold in Young's modulus. Wear resistance (established for different loads: 0.1, 0.2 and 0.5 MPa) for Al-Si+Ti-Al-C was two times higher than for the sole matrix, while for Al-Si+Ti-Si-C the improvement was up to 32%. Both composite materials exhibited approximately two times lower thermal expansion coefficients than the matrix, resulting in enhanced dimensional stability.

The article presents the results of investigation of the microstructure and mechanical properties of Fe-based materials intended for the production of semi-spherical liners for experimental shaped charges. The tests were carried out on samples taken in three directions in relation to the rolling direction: 0°, 45° and 90°, of the following materials: cold-rolled sheets made of DC04 steel, hot-rolled sheets made of 04J steel, and cold-rolled strips made of 004G steel developed at Łukasiewicz – IMŻ and annealed at 650°C. Semi-spherical drawpieces with a diameter of 106.4 mm, intended for liners, were made of the sheets with the use of cold stamping. Tests of the microstructure and HV hardness of samples taken from the test batch were carried out on cross-sections along the pressing direction and the model batch – on sections transverse to the stamping direction The geometry of the model batch drawpieces was also measured. The ferrite grain size evaluation was performed according to the ASTM E112 standard using μgrain software with a grain size evaluation module using counting the number of intersections of grain boundaries with a circle.

The paper presents the results of investigation of the microstructure and mechanical properties of Fe-based materials designed for the manufacture of semi-spherical liners for experimental shaped charges. The tests were carried out on material samples taken from two semi-finished products, i.e. a rod for the manufacture of charge liners with a diameter of 50 mm using machining, and sheets for the manufacture of liners with a diameter of 100 mm using cold drawing. Microstructure examination was also carried out on a test specimen obtained using the additive method (3D-WAAM), made of low-carbon unalloyed steel wire. Firing tests on concrete blocks were carried out in order to quantify the effects of drilling at the Experimental Mine Barbara. The scope of the tests consisted of firing at cylindrical concrete blocks using projectiles containing 50 mm diameter liners made of Fe-based alloys. Based on the results of the laboratory material, two experimental steel grades were selected for further testing. Plates made of the selected steels will be used to manufacture charge liners with a diameter of 100 mm.

The aim of this study was to assess sand accumulation in the gastrointestinal tract and fecal sand excretion in Silesian foals using three diagnostic methods and taking into account the sex and age of the animals. Another aim of the study was to compare the three diagnostic methods. The study was carried out on 21 clinically healthy Silesian foals (10 females and 11 males) from 9-28 weeks old grazed on permanent pasture. The sand intake was assessed using a sedimentation test, abdominal ultrasonography and a quantitative evaluation of sand per 100 g of stool. In the sedimentation test, the sand was palpable in the stool of 57.1% of the horses, and clearly visible in 42.9% of the animals. The ultrasound examination revealed the presence of sand in the gastrointestinal tract in 66.7% of the horses. It was limited to a single location in 60% of the horses, while it was present in several regions in 40% of the horses. The mean amount of sand was 0.14 ± 0.33 g per 100 g of stool. It did not exceed 0.1g in 71.4% foals, while it ranged from 0.1-0.5 g in 23.8% foals. In 4.8% of the animals, it amounted to 1.6 g per 100 g of stool. There was no correlation between age and gender and the results. There was a positive correlation between the ultrasound examination and the sedimentation test. Sand may be accumulated in the gastrointestinal tract of foals without any clinical signs. The amount of sand excreted in the stool is not an indicator of the amount of sand accumulated in the gastrointestinal tract. An abdominal ultrasound examination should be combined with a sedimentation test for more specific results.