Steel plate for cold forging and process for producing same

1. A steel plate for cold forging comprising:

a hot-rolled steel plate,

wherein the hot-rolled steel plate comprises: in terms of percent by mass,

C: 0.13% to 0.20%;

Si: 0.01% to 0.8%;

Mn: 0.6% to 2.5%;

P: 0.003% to 0.030%;

S: 0.0001% to 0.008%;

Al: 0.01% to 0.07%;

N: 0.0001% to 0.02%; and

O: 0.0001% to 0.0030%,

with a remainder being Fe and inevitable impurities,

an A value represented by following formula (1) is in a range of 0.0080 or less,

a thickness of the hot-rolled steel plate is in a range of 2 mm to 25 mm, and

an area percentage of pearlite bands having lengths of 1 mm or more is in a range of not more than a K value represented by following formula (2) in a region of 4/10t to 6/10t when a plate thickness is indicated by t in a cross section of a plate thickness that is parallel to a rolling direction of the hot-rolled steel plate,

A value=O%+S%+0.033Al%  (1)

K value=25.5×C%+4.5×Mn%−6  (2).

2. The steel plate for cold forging according claim 1 ,

wherein the hot-rolled steel plate further comprises, in terms of percent by mass, one or more selected from a group consisting of:

Nb: 0.001% to 0.1%;

Ti: 0.001% to 0.05%;

V: 0.001% to 0.05%;

Ta: 0.01% to 0.5%; and

W: 0.01% to 0.5%.