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キーワード:
Crack propagation; Dual phase steel; Laser beam cutting; Laser beams; Micromechanics; Steel research, Blanking; Cut edge; In-situ testing; Laser cutting; Martensitic surfaces; Micro-structural damages; Microscopic Digital Images; Microstructural deformation, Advanced high strength Steel
要旨:
The as-cut microstructures and the subsequent microstructural deformation characteristics of dual-phase steel specimens were analyzed using in-situ biaxial Marciniak tests, microscopic digital-image-correlation and nano-indentation, for two industrially relevant cutting processes: laser cutting and blanking. Interestingly, the strain-to-failure of the former is almost twice that of the latter, even though microstructural damage initiates twice as early (at 8 strain) in the ∼60 µm-thick, fully-martensitic surface layer of the laser-cut affected zone. However, its ∼145 µm-thick, tempered-martensite sub-surface layer provides the toughness to delay micro-damage propagation, arrest the crack growth, and ultimately provide the high strain-to-failure. These observations reveal guidelines to avoid cut-edge failure. © 2019 Acta Materialia Inc.
