首页|Effect of Nb on inclusions and phase transformation in simulated high heat input coarse-grain HAZ of Nb/Ti low carbon microalloyed steel
Effect of Nb on inclusions and phase transformation in simulated high heat input coarse-grain HAZ of Nb/Ti low carbon microalloyed steel
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NSTL
Elsevier
? 2022In this paper, two groups of Nb/Ti low carbon microalloyed steels (Nb-bearing and Nb-free) were obtained through laboratorial methods. The evolution and effect of Nb/Ti-containing complex inclusions were characterised and analysed after being subjected to high heat input thermal simulation of 100 kJ/cm. The results showed that the prior austenite grain size in the coarse grain heat-affected zone (CGHAZ) was not affected by 0.045 wt% Nb addition. However, the acicular ferrite nucleation, induced by effective micron-level inclusions, was inhibited. Nb tended to converge towards the interfaces between the micron-level inclusions and matrix, which had a negative effect on the nucleation potential of acicular ferrite. The re-precipitation behaviour of nano-level inclusions satisfied the dynamic conditions during the high heat input thermal cycle, under which the dislocation movement was inhibited due to the pinning effect of re-precipitation particles. Besides, the size, morphology and composition of nano-level precipitates were changed by Nb (0.045 wt%) addition. In general, the evolution and effect of inclusions in simulated high heat input CGHAZ provide theoretical references for the study of welding performance in Nb/Ti low carbon microalloyed steels.