Patent ID: 8945719
Filing Date: 2015-02-03
Classification: C21D,C22C,Y10T

Abstract:
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,