SYMPOSIA PAPER Published: 01 January 1999
STP14957S

Micromechanical Prediction of Fracture Toughness for Pressure Vessel Steel Using a Coupled Model

Source

A method of analyzing the ductile to brittle transition region of a ferritic steel using a coupled micromechanical model of ductile damage, stable crack growth and cleavage fracture has been developed to improve the definition of upper shelf behavior for actual structures. Ductile damage is modelled using the Gurson model as modified by Tvergaard, along with a specially developed crack growth user element. The probability of cleavage fracture is predicted by post-processing the finite element results using the Beremin model of cleavage fracture. Predictions are made of ductile tearing and cleavage fracture in test specimen and wide plate configurations of A533B steel for a range of temperatures. The coupled model is capable of predicting transition toughness and transition temperature shifts for different levels of structural constraint. An analytically-based definition of the onset of upper shelf temperature (OUST) is the temperature at which the coupled ductile damage/cleavage fracture model predicts a probability of failure by cleavage fracture of 5%. Estimates of the shift in the OUST due to different levels of in-plane crack tip constraint are made using the elastic T-stress as a measure of constraint. There is potential for using the T-stress as a measure of structural constraint in order to determine shifts in transition temperature for materials with degraded toughness.

Author Information

Goldthorpe, MR
TWI, Abington Hall, Cambridge, UK
Wiesner, CS
TWI, Abington Hall, Cambridge, UK
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: E08
Pages: 341–363
DOI: 10.1520/STP14957S
ISBN-EB: 978-0-8031-5396-7
ISBN-13: 978-0-8031-2486-8