The need for complex and accurate three dimensional (3-D) microcomponents is increasing rapidly for many industrial and consumer products. Electrochemical machining process (ECM) has the potential of generating desired crack-free and stress-free surfaces of microcomponents. This paper reports a study of pulse electrochemical micromachining (PECMM) using ultrashort (nanoseconds) pulses for generating complex 3-D microstructures of high accuracy. A mathematical model of the microshaping process with taking into consideration unsteady phenomena in electrical double layer has been developed. The software for computer simulation of PECM has been developed and the effects of machining parameters on anodic localization and final shape of machined surface are presented.

The subject of the work discussed herein and carried out as a part of the Polish National Centre of Research and Development project titled ”Development and implementation of critical technology demonstrators for the new generation of 120 mm tank artillery ammunition” are the results of a research into the influence of LPS (Liquid Phase Sintering) parameters and heat treatment on the mechanical properties of W91Ni6Co3 and W91Ni6Co2.25Fe0.75 alloys, designated PR200 and PR201, respectively. The alloys, as LPS-processed and heat treated, were tested on a strength testing machine to determine their tensile strength (Rm), proof stress (Rp0.2) and elongation (A5). The analysis of the test results resulted in a proposal of manufacturing process parameters to have the alloys tested develop specified mechanical properties. It was found the ternary alloy with chemical composition W91Ni6Co3 and designated PR200 was more promising in the feasibility of producing specified mechanical properties. The alloy, once sintered and heat treated in two stages, could facilitate production of a material with a tensile strength Rm>1400 MPa, a yield strength Rp0.2 > 1350 MPa, a minimum elongation of 11%, and an impact strength > 115 J/cm2.

Tungsten heavy alloys (THA) are used in the defense industry for subcaliber bullet cores due to their high density and strength. Typically methods of joining tungsten rod elements include: soldering, friction welding or threaded sleeve splicing. The properties of the joints were tested for three types of material containing 90.8, 96.2 and 98.2 wt.%. tungsten, density from 17.3 to 18.4 g/cm3 and strength range 400–1000 MPa. Combination in the liquid phase at the sintering temperature was carried out in a vacuum furnace at a temperature of 1520 °C in a hydrogen atmosphere, and tests used pairs of both identical and dissimilar materials. After that, some of the bars were subjected to additional heat treatment at 1100 °C for 3 h. The tests of the mechanical properties in the static tensile test and the measurement of impact strength showed that the obtained strength of the joints was comparable to that of the parent material. The microstructure analysis showed that the resulting joint area, while maintaining the appropriate roughness of the joined end faces of the bars, is homogeneous without areas of the solidified matrix of the joint line. Research showed that it is possible to bond under sintering conditions with the participation of a solid liquid phase of homonymous and dissimilar THA materials. The strength of joints in dissimilar materials was comparable to a tungsten heavy alloy material with lower strength in the bonded pair while homonymous materials were comparable to the original material. The test results provided a good basis for further research in which the obtained pairs of joints will be subjected to plastic working processes.

The results of studies concerning friction welding of Weight Heavy Alloy (WHA) with AlMg3 alloy are presented. The friction welding of density 17.5 Mg/m 3 with aluminum alloy showed that it is possible to reach the joints with the strength exceeding the yield strength of wrought AlMg3 alloy. This strength looks to be promising from point of view of condition which have to be fulfilled in case of armor subcaliber ammunition, where WHA rods play the role Kinetic Energy Penetrators and aluminum is used for projectile ballistic cup.

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The paper presents the impact of selected machining parameters on surface's shape after machining in REDM (Rotary Electrical Discharge Machining). A mathematical model describing the influence of REDM parameters on the final shape and the relative tool-electrode wear is presented. Influence of REDM parameters on the relative tool-electrode wear and the final shape was determined in experimental practice. Results of computer simulation have been confirmed in experimental practice.

The aim of the work was to develop a composite consisting of tungsten powder and other metal powders, with the density close to that of lead (11.3 Mg/m 3), under laboratory conditions. This material should also meet the requirements for bullet cores. In order to check whether the material developed meets the set requirements, the scope of work included: material development, manufacturing cores of bullets from the produced material, manufacturing cartridges using the above-mentioned cores, conducting ballistics tests involving internal, external and final ballistics.

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