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KAWASAKI STEEL TECHNICAL REPORT
No.24 ( April 1991 )

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Development of Extra-deep Drawing Cold-Rolled Sheet Steels for Integrated Automotive Parts

Kouzou Tsunoyama, Takashi Obara, Susumu Satoh, Hideo Abe, Osamu Shibasaki, Nobuhiko Uesugi
Synopsis :
To develop extra-deep drawing (EDDQ) cold-rolled sheet steels for integrated automobile parts, effects of steel chemistry and processing conditions on the mechanical properties of extra-low C steels have been investigated. Strong carbide-forming elements such as Ti and Nb are necessary to stabilize C even in 20 ppm C steels. Ti-bearing steel has superior ductility and drawability to Nb-bearing steel since grain growth at recrystallization is faster in Ti-added steel than in Nb-added steel due to the difference in the precipitate dispersion. A small amount of Nb addition to Ti-stabilized steel is effective in decreasing the planar anisotropy of mechanical properties. High temperature continuous annealing (850-880Ž) and low reduction temper-rolling (about 0.5%) with the use of the Ti and Nb co-addition steels have provided new products with an excellent mechanical property superior to the mechanical property of conventional EDDQ steel. These products have been used for complicated and enlarged automobile parts such as a side outer panel and an oil pan.
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