| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet having low yield stress, excellent deep drawability, and good fabrication brittleness resistance, and to provide a method for producing the same. <P>SOLUTION: The cold rolled steel sheet has a chemical composition which contains a predetermined concentration of C, Si, Mn, P, S, sol. Al, N, Ti, and Nb, with the balance being Fe and impurities, and satisfies the following formulas (1) and (2); has a steel structure having a ferritic grain size number of 9.0 or less; and has mechanical properties in which the amount of hardening by coating and baking is 10 to 35 MPa, wherein formula (1) is -0.0025≤C-(12/93)×Nb-(12/48)×Ti<SP POS="POST">*</SP><0, and formula (2) is Ti<SP POS="POST">*</SP>=max[Ti-(48/14)×N-(48/32)×S, 0]. Here, each symbol of element in formulas (1) and (2) shows the content (unit: mass%) of each element, and max[] in formula (2) is a function which returns the greatest value among the arguments in []. <P>COPYRIGHT: (C)2012,JPO&INPIT |
