In Indonesia, the reliance on foreign countries for military components persists, including tank track links which are crucial for combat vehicles. These components require mechanical properties such ...as wear resistance and toughness to ensure high safety standards. High Strength Low Alloy (HSLA) steel is used, necessitating precise composition and appropriate heat treatment processes. This study varied compositions and heat treatments to achieve desired properties, producing prototypes with five predetermined compositions. The heat treatment process involves initially heating the samples to 860°C for 30 minutes for uniformity, followed by various treatments including quenching in oil, normalizing, and multiple cycles of quenching with tempering at different temperatures and durations to refine microstructure and adjust hardness of the alloy. Results showed optimal mechanical properties in composition no. 4 after normalizing with a blower, achieving a hardness of 31 HRC. This research aimed to optimize mechanical performance during operational conditions through variations in temperatures and holding times.
In this study, the corrosion resistance of uncoated and coated Ferro Nickel-based superalloy (Fe-Ni) strengthened by the precipitation of the ordered fcc y’ Ni3(Al, Ti) was evaluated by cyclic hot ...corrosion testing. Fe-Ni was coated with Cr3C2-20NiCr and NiCrAlY by high-velocity oxy-fuel thermal spray coating and then tested with a mixture solution of 75 wt.% Na2SO4 + 25 wt.% NaCl at 900 °C for 50 cycles. Scanning electron microscopy combined with energy dispersive spectroscopy and X-ray diffraction were performed to investigate the corrosion products and mechanisms. The kinetics of corrosion was evaluated by measuring the mass changes. The experimental results show that the uncoated superalloy with precipitation strengthened in the substrate suffered by spallation and sputtering of the oxide scale. The presence of Cr3C2-20NiCr and NiCrAlY coating layers could significantly improve the hot corrosion resistance with the NiCrAlY layer showing a better protection performance than Cr3C2-20NiCr. A precipitation-strengthened Fe-Ni superalloy with NiCrAlY coating reduced the overall weight gain, which could be attributed to the formation of protective oxide of chromium, nickel, aluminum, and their spinel. The lower corrosion performance of the superalloy coated with Cr3C2-20NiCr layer was due to the presence of chlorine element, which increased the corrosion attack through chlorination.
With the goals of protecting boiler tubes from hostile surroundings, increasing thermal efficiency, and minimizing time losses from damage, thermal-spray coating methods for high-temperature ...operations were created. Ceramic-metal composite materials (e.g., Cr3C2-NiCr) are well known for protecting components from erosion decay in a high-temperature environment. In this investigation, the high-velocity oxy-fuel (HVOF) thermal-spray technique was employed to successfully deposit several variations of feedstocks containing Cr3C2-NiCr and NiCr powders onto a medium-carbon steel substrate, with and without filtering through a 400-mesh screen. Utilizing X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the microstructure features of the deposited coatings were assessed. The experiment results demonstrate that the crystallite and grain sizes of the deposited coatings can be increased by reducing the powder size through a sifting process using a 400-mesh sieve. This procedure also resulted in a coating with a higher density and lower porosity. Furthermore, new compounds including Cr2O3 and MnCr2O4 were formed in the coating layers as indicated by the XRD spectra. These phenomena are in good agreement with the EDS mapping of Cr and O, which reveals highly similar distributions. Manganese was originally a part of the substrate composition. Manganese could diffuse rapidly across the Cr2O3 layer and form the MnCr2O4 compound, indicating the manganese diffusion from the substrate into the Cr3C2-NiCr coating. The formation of MnCr2O4 can be attributed to the prior emergence of the Cr2O3 compound.
