Flood Welding for Forging Die Repair Applications: Microstructure and Mechanical Characterization of the Repair Alloy and Repair/Substrate Interface Akash Belure, Mayank Garg, David Schwam, Tushar Borkar Journal of Materials Engineering and Performance, 2026 Eureka welding alloys are widely used as a potential candidate in the field of forging die repair applications. Eureka 635 (bainitic steel) was deposited as a repair alloy using the flood welding technique on an AISI 4142 tool steel cavity plate. The microstructural and mechanical properties of the 635/4142 interface, along with the bulk Eureka 635 samples from the repair side, were examined using scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray radiography, Vickers indentation, uniaxial tensile testing, and Charpy V-notch impact testing. The results indicated that flood welding provided superior metallurgical bonding and reduced residual stress. The width of heat-affected zone (HAZ) toward AISI 4142 side near the interface is nearly ~ 4.5 mm. The heat-affected zone is notorious for having lower hardness. It requires special attention in die repair to prevent crack initiation. This is attributed to the grain coarsening caused by the thermal flux from the initially deposited layers. The ultimate tensile strength and ductility of the interface samples were consistently lower than the bulk samples in all cases, likely due to the weak heat-affected zones near the interface, which weakened the overall strength of the interface samples.
Investigating the effects of thermal barrier and anti-corrosion coatings on Ni–Ti SMAs’ transformation enthalpy and recovery capabilities through ambient actuation Stephen Asare, Enock Tongyem, Faraji Rajabu, Jones Owusu Twumasi, Antoinette Berry-Snowden, et al. Smart Materials and Structures, 2026 Shape memory alloys (SMAs), such as Ni–Ti, are valuable in structural and aerospace applications for their shape memory and superelastic properties. However, their performance can be degraded by corrosive and high-temperature environments. Although surface coatings such as thermal barrier coatings (TBCs) and anti-corrosion coatings (ACCs) are used for protection, their effects on the phase transformations of SMAs are not well understood. This study evaluates the impact of commercial polymer-based TBC and ACC coatings on the behavior of Ni–Ti SMAs through thermal, mechanical, and microstructural analysis. Results indicate that both coatings maintain the SMA’s phase transformation temperatures. However, the transformation enthalpy decreased for ACC-coated samples and increased for TBC-coated samples compared to uncoated ones. In thermal recovery tests, uncoated samples showed the highest shape recovery, followed by ACC-coated and TBC-coated samples, suggesting a compromise between protection and transformation efficiency. After 100 cycles, ACC coatings deteriorated significantly, while TBC coatings showed only minor cracking. Electrochemical tests confirmed the anti-corrosion effectiveness of the ACC, and thermal analysis verified the insulating property of the TBC. These findings demonstrate the trade-offs between coating functionality and SMA performance, offering practical insights for selecting coatings in SMA systems under thermal cycling conditions.
High tribo-corrosion resistance of Ni-Cr-5Al2O3 thermal spray coating: a comparison of post processing techniques Mayank Garg, Harpreet Singh Grewal, Harpreet Singh Arora Corrosion Reviews, 2025 Engineering materials are known to show degradation in terms of tribo-corrosion characteristics in marine environment. The concurrent increase in erosion and corrosion resistance can make them more appealing for structural applications. The thermal spray coatings are typically used to mitigate the degradation of structural components. Although, the microstructure of as-sprayed coating indicates inconsistency in the form of distinct splats and elemental segregation. Furnace annealing, microwave processing and stationary friction processing (SFP) are performed to improve the non-homogeneous microstructure of the thermal spray coating. SFP has several attractive properties to refine the grain structure and reducing the defects density on the surface. Therefore, SFP has been explored as a surface modification technique for thermal spray coating with an aim to enhance the performance of the processed coating. Slurry erosion and erosion corrosion tests are conducted on as-sprayed and processed coatings at normal and oblique impingement angle. Erosion rate of SFPed specimen is comparatively lower than that of the as-sprayed, furnace annealed and microwave processed specimens in both slurry erosion and erosion corrosion. Furthermore, the SFPed coating indicated least corrosion rate as compare to furnace annealed, microwave coating and as-sprayed coating.
