Purpose The purpose of this paper is comparison of experimental values of the drawing forces to numerical values in different contact conditions, taking into account the appearance of galling which occurs due to of difficult drawing process conditions. Design/methodology/approach The following two research approaches are used in this paper – the physical modeling, realized by the laboratory experiment, and the numerical simulation of the ironing drawing process. By analyzing the obtained results, the technique of physical modeling, with help of the laboratory equipment and numerical simulation by application of the finite element method, can be successfully used in studying the thin sheet ironing – strip drawing process. Findings It is significant to compare values of the deformation forces obtained by physical experiment to values obtained by the numerical simulation. In that way, it is possible to compare applied contact conditions (four lubricants in that case) and estimate matching of experimentally and numerically obtained results of the deformation forces. Presented results point out very good technological characteristics of ecologically friendly lubricant (single-bath) and grease based on MoS2. Significant decrease of the deformation force was achieved by its application, as well as maintaining of the lubricant’s layer during the forming process and almost complete elimination of galling on the contact. Practical implications Numerical analysis of stresses in the working piece wall, during the thin sheet strip drawing, requires precise values of the friction coefficient. It is an important indicator because one can define the contact conditions as the input data for the numerical simulation, based on its values for each type of lubricants and each value of the compressive lateral force. Originality/value The environmentally friendly lubricant tested exhibits a more favorable distribution of the drawing force during the process, mainly in experimental case. Grease based on MoS2 has good lubricating properties but that lubricant is conventional and environmentally unacceptable. Ecologically friendly lubricant can be successfully used in real ironing strip drawing process especially for high values of holding force achieving an increased tool life.

High strength low-alloyed (HSLA) Cr-Mn-Si steels belong to a group of steels that can reach their full mechanical properties after quenching and tempering. Those properties depend both on the temperature and time of tempering. Knowing the tempering parameters, it is possible to reach the desired properties of the treated steel. Some results on investigating the Hollomon-Jaffe equation (in parametric form) application for tempering of HSLA steel, are shown in this paper. The experiments were performed in real production conditions, using a standard material. The quenching was performed at 870 °C, the heating period was always 30 min, with subsequent cooling into the oil bath. The tempering was carried out in temperature range from 480 to 680 °C, while tempering time varied from 15 min to 24 h. The degree of tempering is referred through the hardness values changing. The experimental results have shown a pretty well agreement to tempering parameters, included in Hollomon--Jaffe equation, for this kind of HSLA steel.Quenched steels, from a group of heat-treatable steels, always have high values of both hardness and strength, but pretty low values of impact properties. The residual stresses are also on a high level. So, any kind of tempering has to be done -depending of the steel type. However, the tempering [1-4] is provided in a wide temperature range (even up to Ac 1 point), and then a wide diapason of structures will appear: from the untransformed martensite (with differrent amounts of retained austenite) to the structure, which contains carbide globules into ferrite matrix.Although the tempering temperature shows a dominant influence on the structure changes, the tempering time also has a strong influence but is usually less investigated. One more reason for investigating the tempering time is a fully diffusion character of all processes which are involved in tempering processes [1,4]. In relation with the processes mentioned, many efforts are still made to find out one proper parameter, which will include both the temperature and time of tempering. Only in that way, i.e., on the equivalency of a simultaneous influence of tempering temperature

Hydroxyapatite is a widely used bioceramic material in implant coatings research because of its bioactive behavior when being deposited onto the metallic implant and compatibility with the human bones composition. The coating of nanosized hydroxyapatite was electrophoretically deposited on a blasted surface of stainless steel 316LVM samples at constant voltage, for different deposition times and subsequently sintered in both, vacuum and argon atmosphere, at 1040 and 1000 °C, respectively. Although sintering temperatures needed to achieve highly dense coatings can cause HAp coating phase changes, the possibility to obtain a bioactive coating on 316LVM substrate, without the coatings phase changes due to the nature of the used stoichiometric nanostructured hydroxyapatite is presented in this work. The thermal stability of the used HAp powder was assessed by DTA-TG analyses over the temperature range of 23-1000 °C, i.e., at the or nearby experimental sintering temperature. The microstructure characterization was accomplished using SEM, while phase composition was determined using XRD.

Co-Mo-Cr alloys for dentistry obtained by vacuum precise casting There are several biocompatible Co-Cr-Mo alloy compositions, as well as technological processes suitable for obtaining the tablet samples aimed to produce dental implants and orthodontic devices. Here presented Co-Cr-Mo alloy, besides its biocompatibility, corrosion resistance, and nickel absence, is favorable for its mechanical properties, such as hardness, tensile and fatigue strength. The technology for raw materials preparation and manufacturing of a Co-Cr-Mo alloy for dental implants vacuum precise casting is presented here. Besides the technological process characteristics, there are the chemical analysis of raw materials, alloy obtaining guidelines and microstructure of as-cast samples.

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