The effect of deformation twins on the quasi-cleavage crack propagation in twinning-induced plasticity steels. (15th May 2018)

• Record Type: Journal Article
• Authors: Luo, Z.C.; Liu, R.D.; Wang, X.; Huang, M.X.
• Is Part Of: Acta materialia. Volume 150(2018)
• Page Start: 59
• Page End: 68
• Publication Date: 2018-05-15
• Subjects: Fracture mechanism -- TWIP steels -- Quasi-cleavage fracture -- Twin boundary -- Dislocation; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.03.004
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The present work investigates the crack propagation behaviour in a twinning-induced plasticity (TWIP) steel. At room temperature, the dominant fracture mechanism of TWIP steel is quasi-cleavage, which is assisted by the deformation twins since such fracture mode is circumvented at 573 K as deformation twins are prohibited. The quasi-cleavage fracture mechanism is responsible for the high notch sensitivity and low essential work of fracture (EWF) of TWIP steel at room temperature. Furthermore, the crack propagation process of TWIP steel at 298 K has been characterized quantitatively by in-situ digital image correlation (DIC) technique and J resistance curve ( J-R curve). The results show that the cracking process of TWIP steel at 298 K is stable, even though cleavage patches are observed on the fracture surface. A physical model based on the dislocation behaviour at the crack tip has been proposed to explain qualitatively the mechanism responsible for the stable cleavage cracking in TWIP steels. Graphical abstract: (a) The geometries of pre-cracked specimen used in this paper; (b) the plastic strain ( ɛ yy ) field around crack tip during crack propagation as calculated by digital image correlation (DIC) technique, showing the stable crack propagation accompanied with large plastic deformation; (c) the quasi-cleavage fracture surface, showing a brittle fracture mechanism. Image 1