建築構造用高性能590 N/mm~2級TMCP鋼板「HBL~®440」

摘要

Conventional590 N/mm~2 class steel for building structures, SA440, has been manufactured by a multiple off-line heat treatment processes involving intercritically reheated quenching, in order to achieve low yield ratio required for seismic resistance buildings. High performance 590 N/mm~2 class thermo-mechanical control process (TMCP) steel plate "HBL~®440" for building structures, which can be manufactured without an intercritically reheated quenching, has been developed by applying the uniquely advanced JFE Steel's on-line accelerated cooling system. The developed steel plates from 19 mm to 100 mm in thickness satisfy the specification of SA440 and exhibit excellent weldability and high heat affected zone (HAZ) toughness in welded joints with very large heat inputs. Furthermore members fabricated with the developed steel plates have achieved equivalent plastic behaviors to those of SA440.%従来の建築構造用590N/mm~2級鋼SA440の製造プロセスでは，建築構造用鋼として必要な低降伏比（低YR)特性を確保するために2相域焼入を含む複数回のオフライン熱処理が必須であったが,JFEスチール独自のオンライン冷却設備を活用したTMCP (Thermo-mechanical control process)技術を駆使することにより，2相域焼入が省略可能な高性能590N/mm~2級TMCP鋼板「HBL~®440」を開発した。板厚19mmから100mmの鋼板を製造し，SA440と同等の機械的性質に加え，優れた溶接性と超大入熱溶接部靭性を達成した。また，本鋼材を用いた鉄骨部材が優れた塑性変形性能を有することも確認できた。