| 摘要 |
PCT No. PCT/JP93/00846 Sec. 371 Date Feb. 18, 1994 Sec. 102(e) Date Feb. 18, 1994 PCT Filed Jun. 22, 1993 PCT Pub. No. WO94/00615 PCT Pub. Date Jan. 6, 1994.The present invention provides a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet excellent in paint bake hardenability, non-aging properties and formability, and a process for producing the same. In the present invention, an extremely low carbon steel or extremely low carbon steel containing at least one element selected from the group consisting of Ti and Nb is used as a base steel, and Mn and Cr are positively added thereto, whereby the resultant steel has a mixed structure after annealing. Accordingly, there can be obtained a steel sheet having both a high paint bake hardenability and non-aging properties, and being excellent in formability such as an average r-value (deep drawability). With regard to the paint bake hardenability, the present invention may provide a cold rolled steel sheet and a hot dip zinc-coated cold rolled steel sheet to which paint bake hardening may be optionally imparted in an amount as large as about 10 kgf/mm2 and which also have non-aging properties.
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