Investigation of the brittle failure properties of an A42 pipeline steel butt weld: comparison of the base metal, simulated HAZ and weld metal

摘要

Assessing a flaw acceptability in a welded structure by means of a failure assessment diagram (FAD) can be difficult when accurate data (K{sub}(mat), local behaviors) on the heterogeneous materials of the weld are not available. The aim of this work is to demonstrate that the coarse grained heat affected zone (CGHAZ) is the critical microstructure of the studied weld and to study the behavior mismatch of the different materials. Therefore bending tests on as received weld blanks were conducted and showed failure initiation in the CGHAZ. This microstructure was reproduced using a GLEEBLE 1500 thermal simulator. Charpy V-Notch tests on weld metal (W-M), base metal (B-M) and simulated CGHAZ were made showing the brittleness of the CGHAZ and the mismatch diminution with increasing σ{sub}y. Smooth tensile tests on B-M and W-M showed the same mismatch evolution.