The austenite grain structure of low-alloy steel weld deposits

H. K. D. H. Bhadeshia, L.-E. Svensson and B. Gretoft

Abstract

The shape of austenite grains in low-alloy steel submerged-arc weld deposits has been examined; it is found that the grain morphology can be approximated as a honeycomb of hexagonal prisms with the c-axes aligned along the major heat-flow direction. Methods of determining the grain size from simple stereological measurements are also discussed. An increase in the oxygen content has not been found to reduce the austenite grain size of as-deposited welds.

We examine here the geometric morphology of austenite grains found in low-alloy steel created through submerged-arc welding. By utilising stereological measurements on different sections of the weld, we propose that these grains can be modeled as a honeycomb of hexagonal prisms aligned with the direction of heat flow. The study specifically investigates whether oxygen levels and the resulting inclusion content influence the size of these grains in the as-deposited state. Findings indicate that increased oxygen does not significantly reduce grain size, suggesting that inclusion pinning is ineffective during the high-temperature transformation from delta-ferrite. Ultimately, the work offers a mathematical framework for approximating grain dimensions to improve the accuracy of microstructure modeling in industrial welding applications.

Journal of Materials Science, Vol. 21, 1986, pp. 3947-3951

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