Research and Development > JFE TECHNICAL REPORT >JFE TECHNICAL REPORT No.20 March 2015 - Special Issue on “Steel Plates” and “Welding and Joining” > Development of Shipbuilding Steel Plate with Superior Low Temperature Toughness for Large Heat Input Welding
No.20 March 2015 - Special Issue on “Steel Plates” and “Welding and Joining”
Development of Shipbuilding Steel Plate with Superior Low Temperature Toughness for Large Heat Input Welding
NAKASHIMA Koichi HASE Kazukuni ETO Taiki
Abstract
The “JFE EWELTM” technology and optimization of dispersion of martensite-austenite constituent (MA) has been applied to develop YP390 MPa grade steel plate (YP:Yield point) with superior low temperature toughness for large heat input welding. The “JFE EWELTM” technology consists of minimizing the size of coarse-grained heat affected zone (HAZ) through controlling TiN particles, refining the microstructure of HAZ by using B, Ca. Furthermore, dispersion of MA was controlled by optimization of alloy design such addition of as Si. Suppression of MA formation in the coarse-grained HAZ and promotion of MA formation in the softened HAZ was achieved simultaneously in order to improve the HAZ toughness and the strength of welded joint. The developed steel was produced in an actual plate mill, and showed the satisfactory property of base metal and welded joint of large heat input welding and weldability.
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