Characteristics of Welded Joints using new EH47-TM Grade Steel Plates of Heavy Thickness

摘要

YP460MPa grade steel was developed for larger size container ships above 10,000TEU grade. Optimum alloy design of Cu-Ti-B type and Thermal Mechanical Controlled Process (TMCP) were applied to fulfill the requirements of YP460MPa class steel plates. The matrix is composed of fine bainite and acicular ferrite microstructures without regarding to thickness direction, and through fine microstructure control of matrix, both tensile strength and impact toughness of matrix got excellent values that exceed the requirements of ship classification. The weldability of new EH47-TM steel plate using FCAW, SAW and EGW processes was investigated. Regardless of welding processes, mechanical properties of welded joint showed good values with respect to ship classification, and especially, welded joint made by EGW process with 300kJ/cm heat input provided good tensile strength above 580MPa and good impact toughness above 100J at -20℃.