As fuel efficiency requirements increase, the transportation industry continues to seek light-weight metals to use in structural components. Magnesium shows promise with its high strength-to-weight ratio and natural abundance. Unfortunately, conventional methods to extrude the light-weight metal consume large amounts of energy, are costly because they use rare-earth elements, and frequently result in inconsistent or non-uniform internal structures that cause problems in strength and reliability. PNNL’s R&D100 Award-winning shear-assisted processing and extrusion (ShAPE™) process overcomes these challenges to create high-strength structures from harder metals and metal alloys.
The patent-pending ShAPE™ process uses a machine to spin billets or chunks of bulk metal alloy, creating just enough heat through friction to soften the material so it can be easily extruded through a die to form tubes, rods, and channels. The simultaneous linear and rotational forces use only 10% of the force typically needed to push the material through the die in conventional processes. This significant reduction in force enables substantially smaller production machinery, thus lowering capital expenditures and operations costs. Energy consumption is similarly low. The amount of electricity used to make a 1-foot length of 2-inch diameter tubing is about the same as it takes to run a residential kitchen oven for just 60 seconds.
The process yields a material with microstructure grains much finer than the material’s grains before extrusion. These tinier grains and their orientation are typically uniform throughout the product, providing greater strength and ductility. For example, room temperature ductility above 25% has been independently measured, which is a large improvement compared to typical extrusions. Initial research shows that the process greatly improves the energy absorption of the metal as well.
The process can be used to form fully consolidated wire, rods, tubes, or other non-circular shapes using powder, flake, machining waste (chips or swarf) or solid billet. The resulting structures support vehicles for land, water, air, and space, wherever weight is at a premium.
- Could significantly lower power consumption and extrusion force compared with conventional extrusion, eliminating the need for power-hungry resistance heaters
- Enables extrusion of materials that cannot be readily extruded by conventional means
- Can be done at low temperature, retaining or improving the internal structures of the precursor material
- Enhances bulk properties, such as energy absorption, in metal alloys