| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.27 ( November 1992 ) Hot-Rolled, Cold-Rolled and Surface Coated Steel Sheets and Electronics and Instrumentation ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| Development of Bake-Hardening High-Strength Cold-Rolled Sheet Steels for Automobile Exposed Panels Susumu Satoh, Susumu Okada, Toshiyuki Kato, Osamu Hashimoto, Toshitake Hanazawa, Hiroshi Tsunekawa |
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Synopsis : New cold-rolled sheet steels (including those coated) with excellent formability and high bake-hardenability suitable for thinner-gage automobile exposed panels were investigated. (1) High-temperature annealing above 850 and subsequent rapid cooling of a Nb-bearing extra-low C steel (Nb(at%)/C(at%)`1.0) provided an intense {111} recrysrallization texture favorable for deep drawability and some amount of solute C effective for bake-hardenability. (2) This processing principle was applied to develop extra-deep drawing cold-rolled sheet steels with bake-hardenability by using newly developed continuous annealing lines (KM-CAL) capable of high-temperature annealing at approximately 900. (3) Organic composite-coated sheet steels with similar mechanical properties were developed by applying a new organic film baked at a low temperature to the continuously annealed sheet steels. (4) Hot-dip galvannealed sheet steels with extra-deep drawability and bake-hardenability were also developed by using newly installed continuous hot-dip galvanizing lines capable of high-temperature annealing and rapid cooling. (5) These new sheet steels are suitable for thin-gage automotive outer panels such as fenders. |
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