Manufacturing of a hybrid die for aluminium extrusion using additive manufacturing from H13 tool steel

Subtractive manufacturing constraints in aluminium hot extrusion die production limit both the design complexity and repairability of worn dies. This research explored the application of metal additive manufacturing (AM) by processing H13 tool steel using powder bed fusion – laser beam (PBF-LB) to address these limitations. The objective of this project aimed to construct a hybrid extrusion die using the hybrid manufacturing method developed in this study. This approach entails depositing PBF-LB-processed H13 (PBF-LB-H13) powder onto a wrought H13 substrate shaped by subtractive methods. This process challenges the prevailing view of H13 as non-weldable and combines the advantages of both AM and subtractive techniques to produce composite dies. The study began by optimising PBF-LB parameters to fabricate dense H13 components, essential for robust hybrid dies. Building upon this optimisation, further refinements targeted at the initial three layers were implemented to strengthen the interfacial bonding of the hybrid components. Initially, these components exhibited varying microstructures between the PBF-LB-H13 and wrought sides. Through austenitizing, quenching, and tempering, the microstructure was homogenised, resulting in a consistent tempered martensite microstructure across the entire hybrid structure. Tensile tests conducted on these homogenised samples revealed that fractures occurred within the PBF-LB-H13 region, not at the interface, affirming the strength of the bond. The tests demonstrated an ultimate tensile strength of 1717 MPa and an elongation at fracture of 9.42%, notably surpassing that of standalone PBF-LB-H13 samples treated similarly. A hybrid extrusion die, constructed through this approach, underwent field testing and proved resilient to the operational demands of aluminium profile manufacturing. The ability of the die to withstand these conditions validates the use of PBF-LB in creating dies that, when worn, can be repaired by removing the affected area and depositing new H13 material. This research presents a sustainable solution that could significantly reduce the need for complete die replacement, enhancing the longevity and cost-effectiveness of die usage in the industry.