Steel material for cvt sheave, cvt sheave, and method for manufacturing cvt sheave

A steel material for a CVT sheave, the steel material comprising the following components, in terms of mass percent (mass %):

• carbon (C):
• 0.15 mass % or more and 0.20 mass % or less,
• silicon (Si):
• 0.16 mass % or more and 0.30 mass % or less,
• manganese (Mn):
• 0.70 mass % or more and 0.90 mass % or less,
• sulfur (S):
• 0.010 mass % or more and 0.025 mass % or less,
• chromium (Cr):
• 1.80 mass % or more and 1.90 mass % or less,
• aluminum (Al):
• 0.015 mass % or more and 0.035 mass % or less, and
• nitrogen (N):
• 0.008 mass % or more and 0.017 mass % or less, where
• a remainder of the steel material is iron (Fe) and incidental impurities, and of the incidental impurities, phosphorus (P) and oxygen (O) contents are as follows:
• phosphorus (P):
• 0.030 mass % or less, and
• oxygen (O):
• 0.0020 mass % or less;
• wherein
• the contents of the Si, Mn, and Cr components satisfy:
• the above mass % ranges, and
• the following expression (1):
• Fn1=7×Cr−6×Si+4×Mn (1)
• where
• Fn1 satisfies:
• 13.9≤Fn1≤15.5, and
• “Cr,” “Si,” and “Mn” represent the Cr, Si, and Mn contents in mass %;
• and the contents of the Al and N components satisfy:
• the above mass % ranges, and
• the following expression (2):
• Fn2=Al×N×104 (2)
• where
• Fn2 satisfies:
• 1.20≤Fn2≤4.35, and
• “Al” and “N” represent the Al and N contents in mass %.