Advanced Integration in Multi-Scale Mechanics and Welding Process Simulation in Weld Integrity Assessment

Vitek, J.M. ; Wilkowski, G.M. ; Brust, F.W. ; Babu, S.

Oak Ridge National Laboratory

关键词: Modifications;    Steels;    Welding;    Pipelines;    Austenite;   

DOI  :  10.2172/940311
RP-ID  :  ORNL04-0695
RP-ID  :  DE-AC05-00OR22725
RP-ID  :  940311

美国|英语

来源: UNT Digital Library

【 摘 要 】

In this project, mathematical models that predict the microstructure in pipeline steel welds were to be developed. These models were to be integrated with thermal models that describe the time-temperature history in the weld as a function of location in order to derive the spatial variation of microstructure in the weld. The microstructure predictions were also to be combined with microstructure-hardness relations, based on the additivity principle, to determine the spatial variation of hardness in the weld. EMC2 also developed microstructural models based on empirical relationships. ORNL was to pursue the development of more fundamental, theoretically based models. ORNL applied a previously developed model for inclusion formation to predict the extent and nature of inclusions that form during weld cooling from the liquid. This inclusion model was directly integrated with computational thermodynamics capability. A convenient user interface was developed for both the inclusion model and the thermodynamic phase-stability calculations. The microstructure model was based on the simultaneous transformation theory analysis as applied to the transformation of austenite to various ferrite constituents during weld cooling. The model available on the Materials Algorithm Project web site was used. Extensive modification of this model was required to correct problems with compilation and calculations as a function of the computational platform (Unix, Linux, Windows, etc.) that was used. The user interface for the inclusion model and thermodynamic phase-stability calculations was delivered to EMC2 along with the modified and correct microstructure model. Evaluation of the theoretically based model will be carried out and the predictions will be compared with experimental results as well as predictions based on the empirical models developed by EMC2.