The aim of this study is to compare the corrosion resistance of X37CrMoV5-l tool steel after nanostructurization and after a conventional heat treatment. The nanostructuring treatment consisted of austempering at 300°C, which produced a microstructure composed of nanometric carbide-free bainite separated by nanometric layers of retained austenite. The retained austenite occurred also in form of blocks which partially undergo martensitic transformation during final cooling. For comparison, a series of steel samples were subjected to a standard quenching and high tempering treatment, which produced a microstructure of tempered martensite. The obtained results showed that the corrosion resistance of steel after both variants of heat treatment is similar. The results indicate that the nanocrystalline structure with high density of intercrystalline boundaries do not deteriorate the corrosion resistance of steel, which depends to a greater extent on its phase composition.

The article presents results of heat treatment on the high chromium cast iron. The study was carrying out on samples cut from the casting

made from chromium cast iron. Those were hardened at different temperatures, then tempered and soft annealed. The heat treatment was

performed in a laboratory chamber furnace in the Department of Engineering Alloys and Composites at Faculty of Foundry Engineering

AGH. At each stage of the heat treatment the hardness was measured by Vickers and Rockwell methods, and the microscope images were

done. Additionally based on images from the optical microscope the microstructure was assessed. Based on these results, the effect of

hardening, tempering and soft annealing on the microstructure and hardness of high chromium cast iron was studied. Next the effects of

different hardening temperatures on the properties of high chromium cast iron were compared. The study led to systemize the literature

data of the parameters of heat treatment of high chromium cast iron, and optimal conditions for heat treatment was proposed for casts of

similar properties and parameters.

Relatively cold die material comes into contact with the substantially higher temperature melt during the casting cycle, causing high thermal fluctuations resulting into the cyclic change of thermal field. The presented contribution is devoted to the assessment of the impact of temperature distribution on individual zones in the die volume. The evaluated parameter is the die temperature. It was monitored at two selected locations with the 1 mm, 2 mm, 5 mm, 10 mm and 20 mm spacing from the die cavity surface to the volume of cover die and ejector die. As a comparative parameter, the melt temperature in the middle of the runner above the measuring point and the melt temperature close to the die face were monitored. Overall, the temperature was monitored in 26 evaluation points. The measurement was performed using the Magmasoft simulation software. The input settings of the casting cycle in the simulation were identical to those in real operation. It was found, that the most heavily stressed die zones by temperature were within the 20 mm from the die face. Above this distance, the heat supplied by the melt passes gradually into the entire die mass without significant temperature fluctuations. To verify the impact of the die cooling on the thermal field, a tempering system was designed to ensure different heat dissipation conditions in individual locations. At the end of the contribution, the measures proposals to reduce the high change of thermal field of dies resulting from the design of the tempering channel are presented. These proposals will be experimentally verified in the following research work.

A possibility to control the strength, hardness and ductility of the L35HM low-alloy structural cast steel by the applied tempering

temperature is discussed in the paper. Tests were carried out on samples taken from the two randomly selected industrial melts. Heat

treatment of the cast samples included quenching at 900 °C, cooling in an aqueous solution of polymer, and tempering at 600 and 650 °C.

The obtained results showed that the difference in the tempering temperature equal to 50 °C can cause the difference of 121 MPa in the

values of UTS and of 153 MPa in the values of 0.2%YS. For both melts tempered at 600 °C, the average values of UTS and 0.2%YS were

equal to 995 MPa and 933 MPa, respectively. The values of EL and RA did not show any significant differences. Attention was drawn to

large differences in strength and hardness observed between the melts tempered at 600 and 650 °C. Despite differences in the mechanical

properties of the examined cast steel, the obtained results were superior to those specified by the standard.

The main scope of the article is the development of a computer system, which should give advices at problem of cooper alloys

manufacturing. This problem relates with choosing of an appropriate type of bronze (e.g. the BA 1044 bronze) with possible modification

(e.g. calcium carbide modifications: Ca + C or CaC2) and possible heat treatment operations (quenching, tempering) in order to obtain

desired mechanical properties of manufactured material described by tensile strength - Rm, yield strength - Rp0.2 and elongation - A5. By

construction of the computer system being the goal of presented here work Case-based Reasoning is proposed to be used. Case-based

Reasoning is the methodology within Artificial Intelligence techniques, which enables solving new problems basing on experiences that

are solutions obtained in the past. Case-based Reasoning also enables incremental learning, because every new experience is retained each

time in order to be available for future processes of problem solving. Proposed by the developed system solution can be used by

a technologist as a rough solution for cooper alloys manufacturing problem, which requires further tests in order to confirm it correctness.