Abstract
The effect of peak temperature for post-weld heat treatment (PWHT) on the dissolution of Nb-rich carbonitrides, Nb(C,N), in the weldline of an electric resistance welded (ERW) X70 grade pipeline steel was investigated. Selected-area electron diffraction patterns and corresponding electron energy loss spectroscopy mappings revealed both Nb-rich carbonitrides and Ti-rich nitrides, (Ti,Nb)N, in the sample heat-treated to 1080 °C peak temperature. However, only Ti-rich nitrides were revealed in the sample heat-treated to 1220 °C peak temperature. During continuous heating to higher than the Ac3 temperature, i.e., near 1100 °C temperature, the dissolution of Nb(C,N) was observed in dilation and derivative of dilation. This experimental result agreed with the predictions by a DICTRA model. Furthermore, a phenomenological model was developed to explain the volume shrinkage during the dissolution of Nb(C,N) precipitates.
| Original language | English |
|---|---|
| Pages (from-to) | 3351-3363 |
| Number of pages | 13 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 55 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 2024 |
Funding
The authors acknowledge the support of the Natural Sciences and Engineering Research Council (NSERC) of Canada through the Collaborative Research and Development (CRD) grant and Mitacs through the Accelerate program. TEM and EELS characterization were performed at the Canadian Centre for Electron Microscopy (CCEM). Much thanks are given to Lorne Good for his assistance with the Gleeble experiments performed at EVRAZ North America.