The paper presents a technology of layered castings based on the use of a method of mould cavity preparation via spatial skeleton insert. The insert was created as a result of application of 3D printing selective laser melting method. The studied spatial skeleton insert, made from CP2 Ti powder, was placed into the mould cavity directly before pouring grey cast iron. The scope of the conducted studies covered metallographic research using a light microscope and scanning electron microscope with EDS analysis, hardness measurements and abrasive wear resistance tests. The obtained results show that the interaction between the solid spatial skeleton insert and liquid alloy allowed for the production of a casting of pearlitic grey cast iron with flake graphite, containing a surface layer reinforced with titanium carbides. In consequence, a local increase in hardness was obtained and, moreover, an increase in abrasive wear resistance of the whole surface layer of the casting.

This study presents the results of research on the influence of heat treatment parameters—namely, temperature, holding time, and quenching medium (air, water, oil)—on the microstructure and hardness of high-chromium alloy steel X46Cr13. The research included hardening heat treatment of X46Cr13 steel, hardness measurements, and microstructural analysis using light microscopy and scanning electron microscopy (SEM), supported by EDS chemical composition analysis. Based on the conducted studies, it was found that increasing the austenitizing temperature and time results in higher hardness of the X46Cr13 high-chromium alloy steel, regardless of the quenching medium used. Due to the negligible influence of the quenching medium on the hardness of the steel under the analyzed heat treatment conditions, air hardening is recommended, as it reduces quenching-induced stresses compared to water quenching.

The research conducted in this study aimed to determine whether the production of a layered casting in the material system of X46Cr13 steel (working part) and gray cast iron (base part) can be integrated with the hardening process of this steel within the conditions of the casting mold. Accordingly, a series of layered castings was produced by preparing the mold cavity, where a monolithic steel insert was poured with molten gray cast iron with flake graphite. The variable factors in the casting production process included the pouring temperature T_p and the thickness of the support part g. Importantly, given that the hardening of the X46Cr13 steel insert occurred directly within the mold, the selection of casting parameters had to balance the ability to heat the insert to the austenitization temperature Tγ_≥950°C while also creating thermokinetic conditions conducive to the rapid cooling of the system. Therefore, chromite sand—commonly regarded as a rapid-cooling material—was selected as the matrix for the molding material. Based on the conducted studies, it was determined that the thermokinetic properties of this material allowed the surface of the cast working part to be heated to the austenitization temperature. The microstructure consisted of Cr(Fe) carbides within a martensitic-pearlitic matrix, with martensite filling the grains of the primary austenite and pearlite situated along their boundaries. The carbides were primarily located at grain boundaries and, to a lesser extent, within the primary austenite grains. Through transmission electron microscopy and X-ray diffractometry, the type of Cr(Fe) carbide in the microstructure of the working part was identified as M₂₃C₆.

In this paper, the authors analyse the crystallisation of bearing alloys used for heavy-duty plain bearings. The composition consists of tin, antimony, copper, and small additions of modifying elements. All the constituents are present in various amounts in the matrix and primary intermetallic phases. Due to a wide range of solidification factors, like cooling rate and pressure, these can change the sequence of crystallisation or lead to segregation of structural components. The present study compares the equilibrium crystallisation of the studied alloys, calculated with Thermo-Calc software, with the experimental results. Data was acquired using the TDA method for alloys poured into standard sand cups as well as into metallic probes of the same geometry, in cold and heated states. The final experiment was conducted with crystallisation analysis during centrifugal casting of alloys poured into steel and cast-iron model bearing housings with different initial temperatures. The authors made an effort to compare and describe the route of crystallisation of the alloys and the influence of the technological process on their structures. The studies also included an extended examination of the structure of the alloys and phenomena connected with the possible segregation of structural components using SEM and optical microscopy.

The article concerns the technology of layered castings made with a system where the base part is made of gray cast iron with flake graphite and the working part is made of high-chromium steel X46Cr13. The castings were produced using mould cavity preparation method utilizing a molding sand based on SiC. The idea of the research was to perform heat treatment of X46Cr13 steel directly in the casting mould, with the success of this approach guaranteed by selecting molding sand with appropriate physicochemical parameters. During the pouring and cooling of the mould, the temperature on the outer surface of the steel insert was recorded to check if it reached the required austenitization temperature. The castings were then examined for the quality of the bond between the gray cast iron base part and the steel working part, microstructure studies were conducted using light and scanning microscopes, and hardness was measured on the surface of X46Cr13 steel. Based on the conducted research, it was found that the high thermal conductivity of the molding sand made with a silicon carbide base disqualifies it for use in the analyzed technology of integrating heat treatment of X46Cr13 steel with the process of producing a bimetal system with gray cast iron. In the microstructure of the steel, in addition to martensite, pearlite and ferrite were present. Therefore, a satisfactory increase in the hardness of the working surface compared to the annealed state of X46Cr13 steel was not achieved, which ultimately confirmed that the hardening of the steel insert was unsuccessful.