SEDL / STP / STP1526-EB / STP49286S

A Weibull Stress Model to Predict Effects of Weld Strength Mismatch on Cleavage Fracture Toughness

Ruggieri, Claudio
Univ. of Säo Paulo, São Paulo, São Paulo

Pages: 16    Published: Jan 2011

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Abstract

This work describes the development of a toughness scaling methodology incorporating the effects of weld strength mismatch on crack-tip driving forces. The approach adopts a nondimensional Weibull stress, σ¯w, as a the near-tip driving force to correlate cleavage fracture across cracked weld configurations with different mismatch conditions even though the loading parameter (measured by J or crack-tip opening displacement) may vary widely due to mismatch and constraint variations. Application of the procedure to predict the failure strain for an overmatch girth weld made of an API X80 pipeline steel demonstrates the effectiveness of the micromechanics approach. Overall, the results lend strong support to use a Weibull stress based procedure in defect assessments of structural welds.