Strain-age-hardened steel sheet with excellent aging resistance after paint baking and method for producing the same

摘要

Disclosed is a strain age-hardened steel sheet that has both non-aging at room temperature and bake hardenability, and has excellent aging resistance after baking. In mass%, C: 0.0010 to 0.010%, Si: 0.005 to 1.0%, Mn: 0.08 to 1.0%, P: 0.003 to 0.10%, S: 0.0005-0.020%, Al: 0.010-0.10%, Cr: 0.005-0.20%, Mo: 0.005-0.20%, Ti: 0.002-0. 10%, Nb: 0.002 to 0.10%, N: 0.001 to 0.005%, the balance is made of Fe and inevitable impurities, the ferrite fraction is 98% or more, The average grain size is 5 to 30 μm, the minimum value of the dislocation density in the ½ thickness part and the surface layer part of the plate thickness is 5 × 10 12 or more, and the average dislocation density is 5 × 10 12 to 1 × 10 15 / m 2. The strain age-hardening type steel plate with excellent aging resistance after baking, which is within the range of.