Innovation in Multi‑Material Functional Layers for Hot‑Forming Tools Using DED Process

Functional layers play a key role in extending the lifetime of hot‑forming tools exposed to extreme thermal and mechanical loads. This study presents the innovation and development of multi‑material functional layers produced by the Directed Energy Deposition (DED - LB) process, using Nimonic 80A as the matrix material enriched with tungsten (WC) and titanium (TiC) carbides. The deposition was carried out in a single build using two independent powder feeders, enabling controlled adjustment of the reinforcement ratio during the printing process and allowing the creation of heterogeneous functional layers tailored for specific tool regions.

Powder blends with up to 20 % WC and TiC were deposited onto tool‑steel substrates, generating functional layers with spatially controlled reinforcement distribution. Detailed microstructural analyses focused on the functional layer, the stability of the Nimonic 80A matrix and the quality of the transition interface. The dual‑feeder approach enabled smooth compositional changes during deposition, resulting in refined microstructures and improved wear‑resistant behavior.

As the reinforced functional layers provide significantly higher wear resistance and contribute to a longer tool lifetime, the study also addresses the machining challenges associated with their increased hardness and heterogeneity, which form a key component of the research work. Tool‑scale testing on forging mandrels and punching dies showed a marked improvement in wear resistance and extended operational life. These findings highlight the potential of compositionally controlled functional layers produced by the DED - LB process to enhance the performance and reliability of hot‑forming tools.