The influence of heat treatment parameters such as the annealing time and austempering temperature on the microstructure, tribological properties and corrosion resistance of ductile iron have been investigated. It has been revealed that the scratch depth of cast iron samples increases with the extension of the isothermal annealing time (from 30 to 120 min) and the austempering temperature (from 280 °C to 430 °C), while the hardness value decreases. A low value of the scratch depth and a high hardness at low values of the austempering temperature and short isothermal annealing time is related to the presence of martensite. Moreover, the presence of a martensite phase has a beneficial influence on the corrosion resistance of austempered ductile iron.

This paper presents the results of tests on the fabrication of welded joints in S1300QL steel according to the requirements of ISO 15614-14 and ISO 12932. The butt-welded joint without bevel was made from 350 × 150 × 8 mm sheets. The welding process was carried out at the hybrid welding (laser–MAG) station. MAG means metal active gas. The test welded joints were subjected to non-destructive and destructive testing. Visual and radiographic examinations were carried out. The distribution of HV10 hardness was determined in the weld, the heat-affected zone, and the base material. The microstructure of these areas was also analysed for the presence of hard and brittle hardening products and non-metallic inclusions. Tensile strength and yield strength, as well as bending strength, were assessed in the mechanical property tests. The impact test was performed in accordance with ISO 9016.

This study addresses the issues related to the quality of the connection between cast iron liners and inserts in a pressure die-cast automotive engine block, along with the macro and micro wear of the cylinder bearing surface. it was found that the commonly used HPDC high-pressure casting technology of Al-Si alloy engine blocks with cast iron liners, in which the cylinder liner is then recreated, does not ensure their metallic connection. The micro-gap created there becomes thicker as the engine is used, which worsens the conditions for heat dissipation from the sleeve to the block. Locally, on the surface of the cylinder bearing surface, reductions in honing effects and longitudinal cracks were observed. The presented literature mechanism of micro wear of the cylinder bearing surface, dependent on the morphology of graphite segregations, was confirmed. The mechanism of creating micro-breaks in the area of phosphoric eutectic and graphite precipitation occurrence was presented, initiated by the formation of microcracks in the eutectic and delaminations at the eutectic-matrix boundary.

This article presents structural analysis and mechanical property evaluation of two coatings applied using the APS (Air Plasma Spraying) method on a P250GH boiler steel substrate. Two different powders were used for coating deposition: WCCoCr, based on tungsten carbide, and CrCNi, based on chromium carbide. To assess the coating-substrate bond quality, a scratch test was conducted using a Rockwell diamond indenter under a constant load of 10 N, moving from the substrate toward the coating. No delamination at the coating-substrate interface was observed, indicating a high-quality bond. Microhardness measurements were performed using a 200 g load. The average microhardness values were 886 HV0.2 for the WCCoCr coating and 904 HV0.2 for the CrCNi coating. The coatings were also tested for cavitation resistance according to the ASTM G32-16 standard. Surface roughness profiles were measured before and after 120 minutes of cavitation exposure. Cavitation wear was evaluated based on the difference in roughness values, determined by the Sz parameter, which, according to ISO 25178, is defined as the difference between the highest peak and the lowest valley on the surface. The obtained results indicate that APS thermal spray coatings based on tungsten carbide powders can be used for machine components to enhance cavitation erosion resistance.

The article presents structural investigations and mechanical properties of hard coatings deposited by spraying WCCoCr powder in an argon-hydrogen plasma jet onto the surfaces of AlSi10Mg alloy casting plates. Two variants (A and B) of processing parameters of the powder spraying process onto the surface of silumin plates were applied, resulting in different coating thickness. The coating applied according to variant A was done with 12 passes, and its thickness was approximately 150 μm. The coating applied according to variant B was done with 20 passes, and its thickness was about 320 μm. The microstructures of these coatings are similar, consisting of wavy, alternately deposited phases of solid solutions with varying concentrations of elements, and fine spherical phases, irregularly dispersed carbides. A qualitative analysis of the distribution of microstructure components was performed based on surface mapping. Precipitates differing in their degree of grayness and shape were identified based on microanalysis of their chemical composition. The porosity assessment of coatings performed in five randomly selected areas amounts to an average of 9%. The applied coatings exhibit good adhesion to the substrate, as evidenced by the absence of delamination during scratching tests using a diamond Rockwell indenter loaded with a force of 10 N. The coating hardness averaged 1180HV0.2. The test results indicate the high quality of the WCCoCr coatings, regardless of their thickness.