HyForge(TM) - Low Pressure Casting material: a game changer towards high quality and cost- effective forging

In the HyForge project, Hydro, Raufoss Technology, Raufoss Development, and SINTEF have worked together to explore the potential of using cast aluminum alloys for the production of forged components for the automotive industry without going through the traditional extrusion process. Such a new and shortened process route will save time, costs, and energy consumption, and be a game-changer for the production of the next generation of forged aluminum components. The core of the project has been to study cast material produced using Low Pressure Casting (LPC), a new casting technology for press bolts developed by Hydro Aluminum R&D. The technology enables the casting of bolts with small dimensions, dimensions that are currently achieved through extrusion. Additionally, the material has a very uniform structure, no casting defects, and a smooth and fine surface with minimal shrinkage porosity, which would otherwise need to be machined away. The research questions the project has been working to answer are: Can this cast material be directly used in industrial forming and forging processes without going through extrusion as it is done today? What changes in the forming and forging processes need to be made for the cast material to achieve mechanical properties comparable to current extruded materials? The results of the project have successfully shown that cast material can compete with current extruded alloys in terms of properties. However, alterations of the process route are necessary to fully exploit the potential of the cast material. The project has linked the results obtained at the laboratory scale with tests conducted on an industrial scale. Several experimental tests at the laboratory scale have been carried out to gain a better understanding of the connection between the chosen alloy, its response during forming and heat treatment, and the resulting mechanical properties. The experiences have then been transferred to full-scale industrial production of the project's selected demonstrator, a wheel suspension system. Raufoss Technology and Raufoss Development have made the necessary adjustments and changes to the production line to produce wheel suspensions from cast material with satisfactory results. In addition to the experimental work, models of the material, fracture criteria, and simulations of relevant tests and production stages have been established. These have been used to support the experimental activity and gain a better understanding of what happens during the forming processes. An accurate material model is necessary to rely on simulations and models of future products based on cast bolts.

The main outcome of HyForge is increased knowledge about how to utilize cast material for forging of high-quality suspension components, with the successful production of a demonstrator, reaching the requirements set for current products. The project will contribute to increased turnover and production of forgings at reduced cost in the years to come. Hydro Aluminium has entered the forging industry both at national and international level. Now, established as one of the main suppliers for premium forging stock in Europe, currently delivering cast stock ready to forge with a lower CO2 footprint compared to competitors. Raufoss Technology and Raufoss Development have successfully produced the project demonstrator in their production line which show that mechanical properties meeting property requirements can be obtained by forging from cast material. They have secured their global business position, extended existing business and opened new markets, and achieved a 20% increase in volume production, contributing to increased Norwegian export. A successful large volume implementation will provide a significant reduction in production cost. The project contributes to reduced energy consumption and material usage by eliminating extrusion from production process, in addition to offering CO2 savings by changing the source of the forging stock. For the society at large, the competence developed in HyForge will contribute to upholding and extension of the lead in aluminium forging technology in Norway and internationally, securing and increased employment at Husnes and Raufoss. The project partners can transfer competence built in the project to help other industries in their innovation attempts.

Forging is a process perfectly suited for forming advanced aluminium automotive parts with extremely high strength and fatigue properties and with a high degree of geometric freedom. Due to these attributes, the automotive industry is increasingly turning to forged aluminium components for light weighting suspension parts such as suspension arms, steering knuckles, and wheel carriers. The only disadvantage of components based on the forging process is the higher cost compared to solutions based on processes such as sheet forming, casting or extrusion. The main existing process routes to produce forging stock suffer from low quality ingots thus requiring extra process steps to fulfill the extreme product quality required for such forgings. In principle these extra steps are required to remove any inhomogeneity, at or close to the surface, detrimental to the product quality. The idea of this project is to exploit a new way of producing high quality ingot material for forging to drastically simplify and shorten the process route, and thereby to achieve to achieve a 80 MNOK/year increased turnover and produce forgings at reduced cost. The new route relies on the recently developed Low Pressure Casting (LPC) of Hydro Aluminium R&D. The LPC enables casting of small dimension billets of high strength and high quality that can be forged without the need for extra process steps. The main challenge in this project is to adjust the alloy and the process route with respect to each other such that the forged product fulfills the requested specifications. The approach is highly innovative as it combines the most recent innovation in casting, LPC, by Hydro R&D with tailored advances in forging processes for most demanding product applications.