Microstructure and microtexture assessment of delamination phenomena in charpy impact tested specimens

• Published in: Materials research (São Carlos, São Paulo, Brazil) Vol. 17; no. 5; pp. 1238 - 1250
• Main Authors: Haskel, Hudison Loch, Pauletti, Ederson, Martins, Juliana de Paula, Carvalho, André Luis Moreira de
• Format: Journal Article
• Language: English
• Published: ABM, ABC, ABPol 01-10-2014; Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
• Subjects: API 5L X70 steel; Charpy impact test; Crack propagation; Delaminating; Delamination; EBSD technique; ENGINEERING, CHEMICAL; Ferrite; Fracture mechanics; High strength low alloy steels; MATERIALS SCIENCE, MULTIDISCIPLINARY; METALLURGY & METALLURGICAL ENGINEERING; Microstructure; Microtexture; Orientation; EBSD technique; delamination; Charpy impact test; API 5L X70 steel; microtexture
• ISSN: 1516-1439; 1980-5373; 1516-1439; 1980-5373
• DOI: 10.1590/1516-1439.268314

In this article the delamination phenomena, which occurs in the X70 steel during fracture process from the Charpy impact tests, was investigated. Microstructure, microtexture and Taylor factor map analyses were performed by scanning electron microscopy, light microscopy and electron backscatter diffraction, respectively. In a cross-section of two fractured surface regions namely, in the perpendicular and parallel regions to the propagation fracture direction where delamination occurred, it was possible to notice that delamination showed a key role in the anisotropy of impact toughness between the L-T and T-L orientations. The results also revealed that the cause of the delamination can be attributed to the presence of microstructural banding and elongated ferrite grains aligned in a rolling direction. The presence of (100)[011] and (111)[110] crystallographic orientations, with Taylor factors close to 2.7 and 4.5, respectively, were identified in the delamination region. They contribute to the occurrence of cleavage delamination during the fracture process.