The high intensity cold rolling for super deep drawing which is superior in compactibility and weldability the black sheet and the production mannered

摘要

This invention high intensity for the useful super deep drawing is something regarding the black sheet and the production method in use of the automobile steel sheet and the like. This black sheet weight % with, C: 0.010% or less, Si: 0.02% or less, Mn: 1.5% or less, P: 0.03 - 0.15%, S: 0.02% or less, Sol.Al: 0.03 - 0.40%, N: 0.004% or less, Ti: 0.005 - 0.040%, Nb: 0.002 - 0.020%, in this B: 0.0001 - 0.0020% Mo: 1 or 2 kinds and the remainder Fe which are selected from 0.005 - 0.02% and in addition it is constituted with the inevitable impurity,Description above P, Mn, Ti, Nb and B relational expression 1 is satisfied according to the strength of desire, [Relational expression 1-1] tensile strength 35kg class and 40kg class 29.1+89.4P (%) +3.9Mn (%) - 133.8Ti (%) +157.5Nb (%) +0.18 [B (ppm) or Mo (%) =35 - 44.9 [Relational expression 1-2] tensile strength 45kg class 29.1+98.3P (%) +4.6Mn (%) - 86.5Ti (%) +62.5Nb (%) +0.21 [B (ppm) or Mo (%)]=45 - 50Description above Ti and N, C, Nb the following relational expression satisfies 2 and 3, [Relational expression 2] 0.6 (1/0.65) (Ti-3.43N)/4C3.5 [Relational expression 3] 0.4 (1/0.35) (Nb/7.75C) 2.2It is something which Ti system and the Nb deposit are distributed at the average size 30 - 60nm. In addition, it offers also the black sheet and the production method which possesses plated layer on the surface of the above-mentioned steel sheet.