Microstructure and Mechanical Properties of Gradient Interfaces in Wire Arc Additive Remanufacturing of Hot Forging Die Steel

Abstract

Hot forging dies are subjected to periodic thermal stress and often fail in the forms of thermal fatigue, wear, plastic deformation, and fracture. A gradient multi-material wire arc additive remanufacturing method for hot forging dies was proposed to extend the service life of hot forging dies and reduce total production costs. The properties of multi-material gradient interfaces play a critical role in determining the overall performance of the final products. In this study, the remanufacturing zone of a hot forging die was divided into three deposition layers: the transition layer, the intermediate layer, and the strengthening layer. Experiments of wire arc additive manufacturing with gradient material were conducted on a 5CrNiMo hot forging die steel. The microstructure, microhardness, bonding strength, and impact property of gradient interfaces were characterized and analyzed. The results revealed that the gradient additive layers and their interfaces were defect-free and that the gradient interfaces had obtained a high-strength metallurgical bonding. The microstructure of the gradient additive layers presented a gradient transformation process of bainite-to-martensite from the bottom to the top layer. The microhardness gradually increased from the substrate layer to the surface-strengthening layer, forming a three-level gradient in the range of 100 HV. The impact toughness values of the three interfaces were 46.15 J/cm2, 54.96 J/cm2, and 22.53 J/cm2, and the impact fracture morphology ranged from ductile fracture to quasi-cleavage fracture. The mechanical properties of the gradient interfaces showed a gradient increase in hardness and strength, and a gradient decrease in toughness. The practical application of hot forging die remanufactured by the proposed method had an increase of 37.5% in average lifespan, which provided scientific support for the engineering application of the gradient multi-material wire arc additive remanufacturing of hot forging dies.

The Influence of the Hot Working Tool Steel Substrate Material on the Element Distribution, Microstructure and Hardness of Gas Metal Arc Welding Hardfaced Layers

“…The powder-based surfacing processes show quite important advancement in terms of feedstock materials, where the complex composite materials can be applied [21,22]. The latest studies show also the attempts at using additive manufacturing approaches for local and precise die remanufacturing, mainly by directed energy deposition (DED) processes, like laser metal deposition [23][24][25] or wire arc additive manufacturing (WAAM) [26]. Finally, quite complex approaches are tested under laboratory-or semiindustrial conditions too, for example, gradient multi-materials wire arc additive remanufacturing presented by Ni et al [26] or hybrid remanufacturing, where at least two various processes are used, like GMAW hardfacing with further nitriding as described by Kaszuba [27] and Widomski et al [28].…”

Strategic Selection of Refractory High-Entropy Alloy Coatings for Hot-Forging Dies by Applying Decision Science

“…The service life of hot-forging dies is pivotal in ensuring the quality of the forged products and the overall efficiency of the forming process. Achieving an extended die lifespan involves selecting the most suitable die material and optimizing die design to enhance thermal fatigue and wear resistance and minimize plastic deformation and surface fracture [1,2]. The selection of conventional hot forge dies with improved die life and performance is based on several factors, including alloy composition, heat treatment, cleanliness, and forging conditions.…”

“…This, in turn, helps prevent deformation or distortion during forging operations, considering the temperatures and press loads involved. Additionally, there is the option to explore the implementation of a multi-material gradient layer [1] between the RHEA and the substrate die material. This layer/s can be designed to have low thermal conductivity while promoting better bonding between the substrate and the RHEA, should the need arise.…”