This article focuses on evaluating the service life of components made from H13 tool steel manufactured using additive manufacturing, specifically 3D printing. This was done by comparing them with components produced by conventional manufacturing methods. H13 tool steel is widely used due to its high mechanical strength and resistance to thermal cycling, properties which are particularly important in high-pressure die casting (HPDC) applications. In such processes, components are regularly subjected to significant mechanical and thermal stresses. The article provides a comprehensive comparison of dimensional stability, porosity, surface roughness, hardness, and operational wear in conventionally and additively manufactured H13 components. Additional measurements of surface roughness were conducted to provide further insight into the material’s surface condition and the overall reliability of the additively manufactured components. The results provide insight into the advantages and limitations of additively manufactured H13 components and support their potential industrial application in high-pressure die casting.
The present study investigates the effect of starter-block diameter-to-height (D/H) ratio on grain selection, crystallographic orientation, solidification microstructure, and γ′ precipitate morphology in directionally solidified CMSX-4 single-crystal castings. Starter blocks with D/H ratios of 0.3, 0.5, and 0.7 were produced using a Bridgman-type directional solidification process at a withdrawal rate of 9 mm/min. Laue X-ray diffraction, optical and scanning electron microscopy, image analysis, and ProCAST numerical simulations were employed to evaluate the crystallographic and microstructural characteristics of the castings. All investigated castings exhibited single-crystal growth in the examined cross-sections. The measured misorientation angles from the preferred crystallographic orientation were 6.3°, 21.7°, and 3.3° for D/H ratios of 0.3, 0.5, and 0.7, respectively, indicating a non-monotonic dependence on starter-block geometry. The relatively large misorientation at D/H = 0.5 was associated with altered local thermal conditions, increased sensitivity to lateral heat extraction, and possible destabilization of the solid-liquid interface. Stray grains were observed in the D/H = 0.3 and 0.5 castings but were not detected in the D/H = 0.7 casting. The simulations indicated that the solidification front advanced into the colder furnace region beyond the heat baffle, where the local thermal gradient decreased substantially and could promote wall-associated stray-grain nucleation. Nevertheless, the survival of these grains was also influenced by dendrite alignment and competitive growth. The measured primary and secondary dendrite arm spacings showed substantial overlap, and no statistically conclusive relationship with the starter-block D/H ratio was identified. Grain-count analysis demonstrated a progressive reduction in grain density with increasing distance from the chill plate. Both D/H ratio and distance had statistically significant main effects, whereas their interaction was not significant. Image analysis of γ′-related regions in the primary dendrite cores showed comparable area fractions and broadly similar shape descriptors for D/H ratios of 0.3 and 0.5, while the lower feature count at D/H = 0.5 suggested a relatively coarser or more interconnected morphology. Overall, the results show that starter-block geometry primarily affects local thermal conditions and competitive grain selection, thereby influencing crystallographic quality and stray-grain formation, whereas its effect on average dendrite spacing and local γ′ morphology was comparatively limited within the investigated conditions.
The paper presents the results of nanoindentation testing of AZ91 magnesium alloy and a WCCoCr coating deposited by Air Plasma Spraying (APS). In order to determine the material properties of individual components of the microstructure of the AZ91 alloy and the WCCoCr coating, i.e., Vickers hardness – HVIT, indentation hardness – HIT, and indentation modulus - EIT, nanoindentation testing of the individual microstructural components of the AZ91 alloy and the WCCoCr coating was performed. The analysis showed significant differences in material property values between the α-Mg matrix, the γ-Mg17(Al,Zn)12 intermetallic phase, the β(α+γ) eutectic, and the WCCoCr coating. The highest values of indentation hardness and indentation modulus were found in the case of the microstructure (grains) of the WCCoCr coating. The obtained results indicate that the application of the WCCoCr coating significantly improves the tribological properties of the surface layer of AZ91 alloy castings, especially scratch resistance. The results of these tests complement the previously performed scratch tests of the WCCoCr coating.
This article presents a systematic study of the effect of tungsten additions as a modifying alloying element and of the subsequent T7 heat treatment on the corrosion stability associated with the microstructural characteristics of the hypoeutectic aluminum alloy AlSi5Cu2Mg. The corrosion resistance of aluminum alloys generally depends primarily on electrochemical potential differences between the solid solution matrix and the present intermetallic phases, whereby targeted microstructural modification can thermodynamically and kinetically stabilize the surface against local galvanic degradation. The aim of this work was to elucidate the combined action of microstructural and electrochemical mechanisms in the experimental alloy. The experimental alloy with graded tungsten additions (0.05, 0.10, and 0.15 wt. % W) was prepared by gravity casting into a metal mold. Corrosion resistance was evaluated through long-term immersion exposure tests in a 3.5% NaCl solution for 20, 40, 60, and 80 days and electrochemical potentiodynamic polarization tests. In the cast state, the addition of tungsten reduces galvanic microcells and shifts the corrosion potential toward more noble values, which was optimally demonstrated at a concentration of 0.15 wt. % W, where the corrosion rate decreased to 0.0192 mm/year. The T7 treatment enabled effective redistribution of copper and magnesium, thereby eliminating the heterogeneous phases (θ-Al2Cu and β-Mg2Si) that cause intergranular degradation. The variant with 0.15 wt. % W after T7 heat treatment, which recorded the lowest corrosion current density (0.69 μA/cm2) and a minimum corrosion rate of 0.0095 mm/year due to the dominant suppression of the corrosion mechanism kinetics and matrix stabilization.
The paper presents the results of material properties investigations (nanoindentation test) of an Al2O3-TiO2 coating with a NiAl interlayer, deposited by the APS (Atmospheric Plasma Spraying) method on an AlSi7Mg alloy casting. The scope of research included the analysis of the microstructure and chemical composition of the substrate material, powders, and coatings, substrate surface preparation, coating fabrication, and the analysis of nanoindentation test results, determined according to the Oliver-Pharr method. The analysis of the nanoindentation test results indicates significantly higher values of material properties, including hardness and elastic modulus, for the Al2O3-TiO2 coating and the NiAl interlayer compared to the AlSi7Mg alloy substrate, with a gradual increase in properties observed from the substrate toward the auter ceramic layer. The obtained results confirm the possibility of using the Al2O3-TiO2 coating as TBC – Thermal Barrier Coatings to improve the operational durability of internal combustion engine components made of Al-Si alloy.
