Kobe Steel Develops 1,180 MPa TBF High Tensile Sheet for Automobile

Kobe Steel announced on Wednesday the firm developed Trip Aided Bainitic Ferrite (TBF) which is high tensile steel sheet with much improved workability and delayed failure property. The firm also announced Nissan Motor adopts cold rolled TBF steel sheet with 1,180 MPa strength for major component of car body framework on new vehicle family released in 2013. This is the first case to adopt 1,180 MPa class cold rolled steel sheet formed by cold pressing to car body framework.

TBF steel sheet has microscopic crystalline structure of below 1 micrometer compared with conventional dual phase (DP) steel with 3-micrometer crystalline structure. TBF steel sheet is consisted of two functional layers, a base layer with high strength and the second layer with high elongation property. This composition also contributes to improvement of delayed failure property. Elongation property is almost double of DP steel.

Kobe Steel successfully developed TBF steel sheet by improvement of manufacturing processes, chemical additives and heat treatment and realized the products with 980-1,470 MPa tension capacity. 980MPa class TBF steel has already been adopted by automobile makers.

Kobe Steel and Nissan Motor have cooperatively tried to achieve material property these years. Nissan Motor developed new spot welding method and decided adoption of 1,180 MPa class TBF steel.

Kobe Steel recently decided installation of continuous annealing line at PRO-TEC which is a joint galvanizing steel maker in the U.S.A. while started deliberation joint business with European, Indian and Chinese steel makers along its global strategy to enhance high tensile steel sales. The firm produces TBF steel at Kakogawa iron works, Japan, eyeing offshore production in future.