Effects of Intermetallic Diffusion and Layer on the Fracture Mechanism of the Al–(Si)‐Coated 22MnB5 Plate by Magnetron Sputtering

Although the application of hot‐dipped Al–Si‐coated steel in production processes prevents the high‐temperature oxidation and decarburization of uncoated steel, its intermetallic compounds and Kirkendall void cause embrittlement. Physical vapor deposition techniques such as magnetron sputtering (MS) have a lower working temperature, which can prevent the formation of alloy layers during coating preparation, thereby alleviating the imbalance in diffusion and embrittlement caused by Kirkendall void. Herein, Al–(Si)‐coated 22MnB5 steel is prepared via MS to compare the differences in morphology, element diffusion, alloy phase composition, and fracture toughness after hot stamping the Al–(Si)‐coated steel prepared by hot dipping. The results show that because of the lack of preformed alloy phase layers, the elemental diffusion of MS Al–(Si)‐coated steel during hot stamping is not suppressed, and the elements in the diffusion layer diffuse evenly, with a limited number of holes generated. In the MS Al–(Si)‐coated steel, the ratio of the alloy phase layer to the diffusion layer is ≈0.8, while the ratio for hot‐dip coated steel is 1.8, indicating that the hot‐dipped Al–(Si)‐coated steel produces more brittle intermetallic compound (IMC) phases during hot stamping, resulting in higher embrittlement caused by IMC phases during processing.