Title: Properties of newly-developed hot-rolled high-strength sheet steels with phosphorus

Authors: Toshiyuki Kato, Masatoshi Shinozaki, Kozo Tsunoyama, Toshio Irie, Nobuo Aoyagi

Addresses: Kawasaki Steel Corporation, Research Laboratories, Kawasaki-cho, Chiba, Japan. ' Kawasaki Steel Corporation, Research Laboratories, Kawasaki-cho, Chiba, Japan. ' Kawasaki Steel Corporation, Research Laboratories, Kawasaki-cho, Chiba, Japan. ' Kawasaki Steel Corporation, Research Laboratories, Kawasaki-cho, Chiba, Japan. ' Kawasaki Steel Corporation, Research Laboratories, Kawasaki-cho, Chiba, Japan

Abstract: Two types of hot-rolled high-strength sheet steels were developed. C-Mn-P steel with phosphorus content more than 0.04% and processed at a coiling temperature of less than 200°C exhibits very low yield ratio less than 70%, and superior properties in ductility, stretch flangeability, fatigue and bake-hardenability. It does not show 2nd cold work embrittlement due to P and brittleness of the heat affected zone of the welded joint. This steel is suitable for components which require high formability, such as wheel discs. The other type is an Nb-containing high-strength sheet steel with P addition instead of increasing C, that is, low carbon equivalent value. It also shows good ductility and superior stretch flangeability. Less hardenability of the welded zone of this steel results in a superior formability and touchness of the welded joint and makes it possible to apply this steel to a wheel rim.

Keywords: flash butt welded joints; formability; high strength sheet steel; hot-rolling; phosphorus; solid solution hardening; reduced hardenability; welded zone; wheel rims; welded joints toughness; ductility; stretch flangeability.

DOI: 10.1504/IJMPT.1987.036782

International Journal of Materials and Product Technology, 1987 Vol.2 No.3/4, pp.356 - 376

Published online: 07 Nov 2010 *

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