| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 827937 | Materials & Design | 2016 | 6 Pages |
•The reasons for the poor formability of α-matrix-based high Al steel have been found.•Large lattice misfit and lamellar structure cause the materials cracking.•A flash processing using electric current changes the microstructure.•The cold formability of lightweight steel can be improved drastically by the electric current processing.
κ-Carbide (κ) in high aluminium (Al) steels is grown from austenite (γ) via γ → γ + κ or γ → α + κ (α represents ferrite), and is a lamellar structure. This work demonstrates that the formability of high Al lightweight steels is affected by the lattice misfit and interface shape between κ and matrix. The cold workability can be improved by either to change the steel chemical constitution or to implement an electro-thermo-mechanical process. For ferrite-matrix-based high Al steel, electric-current promotes the spheroidization and refinement of κ structure and reduces volume fraction of κ phase. This retards the crack nucleation and propagation, and hence improves the materials formability. The observation is caused by a direct effect of electric-current rather than side effects.
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