The aim of the paper was to investigate the structure and properties of the carburized surface layer of the 35CrSiMn5-5-4 steel after the nanostructurisation with the austempering heat treatment. During vacuum carburizing the surface layer of the steel was enriched with carbon above w = 0.6 %. Steel samples were subsequently austenitized, quenched at two different temperatures, 260°C and 320°C, and annealed at these temperatures for the time necessary for the completion of the bainitic transformation. For comparison, one set of carbonized samples was subjected to the conventional heat treatment: martensitic quenching and low tempering. The microstructural characterisation of the steel after different heat treatments was performed using scanning (SEM) and transmission (TEM) electron microscopes. It was shown that both austempering treatments led to a carbide-free nano-bainitic structure composed of nanometric ferrite plates separated by thin layers of retained austenite. The microhardness and wear resistance of three kinds of steel samples were investigated: the two subjected to the austempering treatment at different temperatures and the one subjected to the conventional treatment. It was shown that the nano-bainitic structure containing an increased amount of retained austenite displays a higher wear resistance than the tempered martensite. The results confirm that austempering can be a competitive method of thermal treatment, in comparison to the conventional heat treatment, for the steels after the carburizing process. Keywords: vacuum carburizing treatment, carburized surface layer, carbide-free bainite, austempering, wear resistance Namen tega dela je preiskati strukturo in lastnosti naoglji~ene povr{ine jekla 35CrSiMn5-5-4 po nanostrukturiranju s toplotno obdelavo austempranja. Med naoglji~enjem v vakuumu se je povr{ina jekla obogatila z ogljikom nad masnim dele`em w = 0,6 %. Vzorci jekla so bili segreti v avstenitno podro~je, ga{eni na dve razli~ni temperaturi: 260°C in 320°C, in zadr`ani na teh temperaturah, potrebnih za popolno bainitno pretvorbo. Za primerjavo je bila serija naoglji~enih vzorcev toplotno obdelana po navadni metodi: ga{enje v martenzit in popu{~ano pri nizki temperaturi. Karakterizacija mikrostrukture jekla po razli~nih toplotnih obdelavah je bila izvr{ena z vrsti~nim (SEM) in presevnim (TEM) elektronskim mikroskopom. Izkazalo se je, da obe toplotni obdelavi austempranja povzro~ita nastanek nanobainitne strukture brez karbidov in sestavljene iz nanometrskih feritnih plo{~ic, lo~enih s tanko plastjo zaostalega avstenita. Pri treh razli~nih vzorcih je bila izmerjena mikrotrdota in odpornost proti obrabi; pri dveh z austempranjem pri razli~nih temperaturah in enem z navadno toplotno obdelavo. Izkazalo se je, da ima nanobainitna struktura s pove~anim dele`em zaostalega avstenita ve~jo odpornost proti obrabi kot pa popu{~eni martenzit. Rezultati so potrdili, da je toplotna obdelava z austempranjem bolj{a metoda toplotne obdelave kot navadna toplotna obdelava za jekla po postopku naoglji~enja...

Introduction and objective. Spinal cord injury (SCI), which disrupts motor, sensory and autonomic functions, causes significant changes in the functioning of an individual. It is believed that most of the conditions secondary to SCI, i.e. osteoporosis, spasticity or cardiopulmonary diseases, are associated with immobility. The aim of the study is to assess the adherence to prescriptions of therapeutic exercises (APTE) in patients with SCI after acute phases of rehabilitation. Materials and methods. The criterionfor APTE recognition was the performance at least twice a week for a minimum of 30 minutes of active exercises with resistance, and exercises maintaining the range of movement of the joints The research tools were own questionnaire and the WHOQOL-BREF scale. Results. 46 subjects (63.9%) met the APTE criteria. The most frequent place for performing the exercises was the subject's home with 43 subjects (93.5%) with APTE performed the exercises in their homes. 17 subjects (36.9%) with APTE performed exercises during stays at various rehabilitation centres. The main cause for the lack of APTE was the limited availability of facilities considered necessary by the respondents to adhere to the instructions. In statistical analysis, the level of neurological injury correlated with meeting the APTE criteria. It was discovered that a subjective assessment of the exercise dose correlated with the place where the exercises were performed, but did not correlate with meeting the APTE criteria. Conclusions. The basic place for performing exercises (as instructed in hospital) was the subject's home. Limited access to reimbursed environmental therapy resulted in an increased cost of exercises supervised by commercially-employed physiotherapists. The current gaps in the system of supervision and counselling of subjects post-SCI necessitate changes in the Polish health care system.

The authors present their experience in the treatment of chronic lower limb ischaemia resulting from atherosclerosis by below knee amputation according to Ghormley's technique, with the immediate application of a semi-rigid plaster cast and early rehabilitation. From a group of 664 patients requiring major amputations, 61 patients (52 men) aged 64 +/- 11 fulfilled the criteria for unilateral below-knee amputation for critical limb ischaemia for atherosclerosis consequences. Peri-operative (30-days) mortality was of 3.28%. Stump healing was very good or good (no need for further surgery) in over 2/3 of patients, but in 20% the need for above-knee amputation developed. Postoperative knee contracture (defined as 15 degrees or more limitation to the movement range) was observed in 11.5% of patients.

Intermediate annealing treatment (IAT) is a new process that accelerates the bainitic transformation in steels. This stimulation is crucial, especially in the prolonged production of nanobainitic steels. Among other recognised methods, it seems to be an effective and economical process. However, there are very few research works in this area. The objective of this study was to collate microstructural changes caused by IAT with differences in the kinetics of the subsequent bainitic transformation in the X37CrMoV5-1 tool steel. Differential dilatometry, LM and SEM microscopic observations, EDS and XRD analysis, and computer simulations were used to investigate the effect of IAT on the kinetics of bainitic transformation. The study has revealed that introducing an additional isothermal heating stage immediately after austenitising significantly affects the kinetics of bainitic transformation—it can accelerate or suppress it. The type and strength of the effect depends on the concentration, distribution, and morphology of the precipitations that occurred during IAT.

The aim of the study was to characterise the microstructure of 35CrSiMn5-5-4 steel which was subjected to a new heat treatment technology of quenching and partitioning (Q&P). The parameters of the treatment were chosen on the basis of computer simulations and dilatometric studies of phase transformations occurring in steel. The transmission electron microscopy (TEM) observations of steel microstructure after the Q&P treatment revealed the presence of martensite as well as significant amount of retained austenite in form of layers between the martensite laths. The rod-like carbides in the ferritic areas were also observed, which indicates the presence of lower bainite in steel. It was found that the retained austenite content measured by means of TEM was about 28% for partitioning at 400°C and 25% for partitioning at 260°C. These results are in good agreement with the phase composition calculated theoretically as well as those determined experimentally by use of dilatometric tests.