Optimising inclusion and toughening the heat-affected zone of ship plate steel with MgO nanoparticles

Abstract

The effect of adding MgO nanoparticles to ship plate steel at welding heat-affected zones (HAZs) was experimentally studied. The results showed that the added nanoparticles obviously optimised the inclusions; the average size of the inclusions was significantly reduced, and the distribution was relatively uniform. The toughness of the base metal and HAZ increased by 20–60 J, apart from a slight decrease in the strength of the fine-grained heat-affected zone and a nearly unchanged strength in the coarse-grained heat-affected zone, and approximately ∼2 μm (Mg–Al–Ti)O-containing inclusions induced acicular ferrite effectively, thereby simultaneously enhancing the strength and toughness of the inter-critical heat-affected zone. In conclusion, these performance improvements in both the base metal and HAZ could be attributed to grain refinement and inclusion optimisation.

KEYWORDS:

• Nanoparticles
• inclusion
• microstructure
• acicular ferrite
• HAZ

Acknowledgements

The authors gratefully acknowledge support from the National Natural Science Foundation of China (Nos. 51734003, 51674023) and the Fundamental Research Funds for the Central Universities FRF-TP-18-009C1.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge support from the National Natural Science Foundation of China [Nos. 51734003, 51674023] and the Fundamental Research Funds for the Central Universities [FRF-TP-18-009C1].