What is it about?

In this study, the fracture toughness of a carbon steel (JIS SS400) that has been used for the penstock of a hydroelectric power plant for about 50 years was examined. By measuring the critical crack tip opening displacement in conjunction with analysis for chemical compositions, the characteristics of fracture toughness was investigated

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Why is it important?

1) There is a strong correlation between the content of carbon equivalent, Ceq, and fracture toughness, δc, of the base metal. 2) Weld metal has lower fracture toughness value of δc compared to that of base metal. 3) No correlation exists between the content of impurity elements (phosphorus, P, and sulphide, S) and fracture toughness values of δc. 4) Ceq is not a prospective parameter to estimate the fracture toughness of the weld metal because of the influence of work hardening.


According to this study, it is obvious that a further study is required to establish a non-destructive evaluation method to predict the fracture toughness of welded joint with reasonable accuracy. In addition, given the historical perspective about 40 years use of high tensile strength steels for infrastructures in Japan, the applicability of our previous and present studies should be examined for these materials by accumulating various field data.

Prof Keiji Yanase
Fukuoka University

Read the Original

This page is a summary of: Analysis on Critical CTOD of Long-Term Used Penstock, Key Engineering Materials, June 2017, Trans Tech Publications,
DOI: 10.4028/www.scientific.net/kem.741.57.
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