Effects of long-term thermal aging on the microstructure and mechanical behaviors of 16MND5/Alloy 152 dissimilar metal weld

The effect of thermal aging on microstructural evolution and mechanical behavior was investigated via advanced instrumental analysis. The scanning electron microscope (SEM) results demonstrated that the microstructure transformed from martensite into martensite/bainite mixture in the coarse-grained heat-affected zone (CGHAZ) of 16MND5. The micro-hardness in the CGHAZ has a significantly positive correlation with thermal aging time owing to the change of microstructure and the increased number of M23C6 precipitates. Moreover, the tensile strength and elongation of the dissimilar metal welds have a positive correlation with thermal aging time. However, the fracture occurs on the Alloy 152 side and the fracture mode was the ductile fracture. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The effect of thermal aging on microstructural evolution and mechanical behavior was studied using advanced instrumental analysis. The microstructure in the coarse-grained heat-affected zone transformed from martensite to martensite/bainite mixture. The micro-hardness in this zone showed a positive correlation with thermal aging time due to changes in microstructure and increased number of M23C6 precipitates. The tensile strength and elongation of dissimilar metal welds also increased with thermal aging time. However, fracture occurred on the Alloy 152 side and exhibited a ductile fracture mode.