| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.40 ( May 1999 ) Steinless Steel and Steel Platel ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Weldability of Advanced Extremely-low Carbon
Bainitic Steel for Thick Plates of 570 MPa
Grade through As-Rolled Process Mitsuhiro Okatsu, Tohru Hayashi, Keniti Amano |
| Synopsis: An extremely-low carbon bainitic steel with about 0.02 mass% or less carbon content can be applied to the manufacture of high strength heavy gauge steel plates because of the unique features such as a granular bainitic ferrite microstructure independent of cooling rate after plate rolling. Being free from martensite transformation due to the decrease in carbon minimizes the hardening of heat-affected zone (HAZ) and the deterioration of HAZ toughness at an increase in the welding heat input. A design to control the microstrucure for extremely-low carbon bainite was applied to develop the new high strength steel plate which can be manufactured with no heat treatments. TS 570 MPa grade steel plated of 38 and 75 mm thickness were produced and the weldability was evaluated. The maximum HAZ hardness value was under 280 in Vickers number even under an arc-strike condition. The HAZ toughness at a heat input of up to 20 kJ/mm showed high Charpy impact energy. |
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