Interpretation and significance of reverse chevron-shaped markings on fracture surfaces of API X100 pipeline steels

Published

August 15, 2012

Author(s)

Christopher N. McCowan, Elizabeth S. Drexler, Jeffrey W. Sowards

Abstract

Fracture surfaces of X100 pipeline steels were examined with optical and electron microscopy following fracture testing. The fractures show chevron-like fracture patterns, but are distinctly different from classic chevron fracture. The chevron-like markings on the fracture surfaces point in the direction of crack growth, rather than towards the location of fracture initiation as observed in classic cases of chevron fracture. Differences between these X100 fractures and classic steel fractures are discussed. Existing models predicting formation of chevron fracture patterns do not explain the fracture behavior observed for X100 pipeline steel. A mechanism is proposed where reverse chevron-like patterns reflect the shape of the crack front itself, and form as a result of crack tunneling along brittle microstructure and intermittent extension of the tunneling crack front.

Citation

Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing

Volume

551

Pub Type

Journals

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DOI Link

Keywords

Chevron markings, CTOA: Fracture, Pipeline steel, X100

Citation

McCowan, C. , Drexler, E. and Sowards, J. (2012), Interpretation and significance of reverse chevron-shaped markings on fracture surfaces of API X100 pipeline steels, Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, [online], https://doi.org/10.1016/j.msea.2012.04.108 (Accessed January 23, 2025)