The chilled casting method is widely used in the metal casting industry to accelerate the mold's cooling rate. This method is very suitable for surface hardening by depositing the elements contained in the chill material onto the surface of the object being cast. One of the factors that influence surface hardness characteristics is the diffusion temperature. This study aims to determine the microhardness, surface layer thickness, and the element contained on the surface. The main material produced into Y-Block is ductile cast iron, the chill material is SS 304 plate with a thickness of 0.2mm. However, before the liquid material is poured into a mold, the chill plate is inserted into the surface of the pattern in the mold, then the plate was preheated. The result showed that the highest preheating temperature has produced microstructure around the surface area namely eutectic carbide of (FeCr)7C3, and (FeCr)3C. SEM-EDX analysis shows that 7.13%Cr is contained on the coating layer at a thickness of 0.020 mm and an average hardness of 700-900 HV.

Twin wire arc spraying (TWAS) is a thermal spray process that is widely used in various industries. Nevertheless, the impact of repeated sandblasting on the coating characteristics of FeCrBSiMn coating created using the TWAS technique has not been extensively researched. Therefore, this study aims to investigate the influence of repeated sandblasting on the properties of the FeCrBSiMn coating layer created using the TWAS process. The study used stainless steel 304, 75B, and FeCrBSiMn as the substrate, bond coat, and top coat materials. The substrate materials underwent sandblasting with a repetition of 1, 2, and 3 cycles before the coating procedure. The coating's quality in this study was assessed using surface roughness, thickness, hardness, corrosion rate, bond strength, and SEM (Scanning Electron Microscope) examination. The findings of this investigation indicate that the sandblasting treatment substantially elevates the surface roughness of 304 stainless steel substrates. As the substrate surface becomes rougher, there is an increase in the percentage of porosity and unmelted material, as well as an increase in the thickness of the coating layer. Furthermore, the hardness of the resulting coating layer diminishes. Specimen A exhibited superior qualities in comparison to the other specimens. The coating layer on this specimen has a percentage of unmelted material and porosity, thickness, hardness, and adhesion of 7.122%, 0.125 mm, 1081.6 HV, and 14.5 MPa respectively. This investigation's results indicate that the substrate material's corrosion rate (x 10−6 mmpy) is 3648.6, which is lower than the corrosion rate of specimen A, which is 37.802.

The gear manufacturing method is an important determinant of their performance and service life. Surface hardness and dimensional accuracy play a significant influence in determining wear and contact fatigue in gears. This study’s goal was to measure the gear profile dimensions and surface behavior of nodular cast iron made using the chill casting technique. Chill plates made of 304 stainless steel with thicknesses of 0.2, 0.4, and 0.6 mm were used to provide good surface cooling rates during the chill casting of gears performed using open molds of silica sand. Chill plates are plated onto the walls of the mold, and then the molten material is poured at 1400 °C. The obtained gears were tested using photographs, microstructures, SEM-EDX, microhardness, wear, and dimensional measurements. The thickness of the chill plate can affect the hardening process of the gear surface. Thicker chill plates result in slower cooling rates, resulting in a more homogeneous microstructure and increasing the hardness level of the hardened layer. Whereas thinner chill plates result in a faster cooling rate, which results in a higher hardness and wear resistance of the hardened layer. Reducing the thickness of the chill plate from 0.6 mm to 0.2 mm increases the cooling rate and increases the amount of diffusion that can occur. The results showed that M₇C₃ and the (FeCrC)₇C₃ matrices were formed, with an average hardness within a range of 700–994.96 HV. A chill plate with a thickness of 0.4 mm produces gear with the best accuracy and precision.

One way to extend the lifetime of gear is minimizing the distortion during the manufacturing process. One of the most important processes in gear manufacturing is induction surface hardening. Induction hardening causes a geometric distortion in gears. This study aimed to analyze the distortion of the gear after induction surface hardening. The material of gear that used in this research is S45C, and it was designed with the a module (m) of 1.75, and 29 teeth (z). In the experiment, the gear was heat-treated using induction hardening at variations of temperatures of 820, 880, and 920 °C with holding time was 35, 45, and 55 s, respectively. Then the gear quenched in water at room temperature. The microstructure analysis was conducted to explore the phase change in gear teeth. Hardness test was also performed on the gear using Rockwell test, and finally, the gear dimension was evaluated. The results showed that the hardness of gear at the teeth surface was 64.9 HRC at the case depth of 5 mm is proper to be used. The microstructure of gear at the surface is martensitic, and the deeper area is pearlite. Gear distortion of all teeth with average thickness was reduced and the highest value was 1.593% at the austenite temperature of 820 °C. While the highest reduction was produced at the temperature of 920 °C and generated the highest shrinkage. The induction surface hardening of the gear was not high, and the highest distortion was found in the outside diameter.