Patent ID: 9718256
Date: 2017-08-01
CPC Classifications: B32B,C21D,C22C,C23C,Y02P

Claim:
1. A steel material for nitriding, having a chemical composition comprising, by mass percent, C: more than 0.15% and not more than 0.35%, Si: 0.20% or less, Mn: 0.10 to 2.0%, P: 0.030% or less, S: 0.050% or less, Cr: 0.80 to 2.0%, V: 0.10 to 0.50%, Al: 0.01 to 0.06%, N: 0.0080% or less, and O: 0.0030% or less, with the balance being Fe and impurities, and further the Fn1 expressed by the formula (1) described below is 20 to 80, and the Fn2 expressed by the formula (2) described below is 160 or more; wherein a microstructure of the steel material is a ferritic-pearlitic structure, a ferritic-bainitic structure, or a ferritic-pearlitic-bainitic structure, an area fraction of ferrite in the microstructure is 20% or more, and a content of V in precipitates determined by an extraction residue analysis is 0.10% or less: where, each symbol C, N, Mo, V, Cr and Al in the above formulas (1) and (2) represents the content by mass percent of the element concerned.