Nucleation Effect of Ca-Oxysulfide Inclusions of Low Carbon Steel in Heat Affected Zone by Welding

Abstract:

In order to achieve excellent toughness of heat affected zone (HAZ) of low carbon steel plates by welding, several microstructure control techniques using fine particles have been developed. In particular, Ca-oxysulfide inclusions have been used in a lot of steel plate products, because they are thermally stable even in near the fusion line of weld joint and they have grain refining effect in HAZ. In cases where heat input is large (>100kJ/cm) and microstructure of HAZ mainly consists of polygonal ferrite, it has been clarified that Ca-oxysulfide inclusions act as nucleation sites of polygonal ferrite in HAZ during the cooling process after welding. However, in cases where heat input is medium (≈50kJ/cm) and microstructure of HAZ mainly consists of bainite, nucleation effect of Ca-oxysulfide inclusions and that of mechanism have not been clarified. This study investigated the nucleation effect of Ca-oxysulfide inclusions in medium heat input welding by in-situ laser microscope observation and the lattice misfit between Fe-matrix and Ca-oxysulfide inclusions.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 130-134
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.130
• Online since: December 2018
• Authors: Yusuke Terazawa*, Katsuyuki Ichimiya, Kazukuni Hase
• Keywords: HAZ Microstructure Control, Low Carbon Steel, Oxides Metallurgy

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