SYMPOSIA PAPER Published: 01 January 1978
STP38088S

Analysis of Fracture Morphology of Hydrogen-Assisted Cracking in Steel and Its Welds

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The relationships between fracture morphology of hydrogen-assisted cracking, microstructure, and crystallographic orientation were investigated using the scanning electron microscope.

In the fracture morphology of hydrogen-assisted cracking, quasicleavage fracture, intergranular fracture, and dimple rupture were observed. In the quasicleavage fracture caused by hydrogen, subcracks often were observed along the boundary of martensite lath or ferrite lath, or both, and at the interface between the matrix and carbides.

The unit fracture facet for hydrogen-assisted cracking, therefore, was defined as the region between subcracks. The unit fracture facet for hydrogen-assisted cracking was smaller than that for cleavage fracture of martensite, upper bainite, and bainitic ferrite. Using the etch pit method the crystallographic orientation of the fracture morphology of hydrogen-assisted cracking was found to be the {110} plane.

The fracture morphologies of hydrogen-assisted cracking can be categorized as one of four types, each of which can be explained by the microscopic diffusion behavior of hydrogen.

Author Information

Kikuta, Y
Osaka University, Osaka, Japan
Araki, T
Osaka University, Osaka, Japan
Kuroda, T
Welding Research Institute of Osaka University, Osaka, Japan
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Details
Developed by Committee: E08
Pages: 107–127
DOI: 10.1520/STP38088S
ISBN-EB: 978-0-8031-5547-3
ISBN-13: 978-0-8031-0359-7