Method of manufacturing cam piece for continuously variable valve duration and cam piece manufactured therefrom

A method of manufacturing a cam piece for a continuously variable valve duration, the method comprising:

• manufacturing the cam piece by casting;
• heating the cam piece;
• maintaining a heating temperature;
• and
• salt-bathing the cam piece,
• wherein the cam piece comprises 3.2 to 4.2 wt % of carbon (C), 2.2 to 3.4 wt % of silicon (Si), and balance iron (Fe), and has a carbon equivalent value according to a formula 1 of 4.4 to 4.6, wherein formula 1 is =wt % C+(1/3) wt % Si,
• wherein the cam piece further comprises nickel (Ni), copper (Cu) and molybdenum (Mo) and a total content of nickel (Ni), copper (Cu) and molybdenum (Mo) is 1.9 to 2.1 wt %, wherein a content of nickel (Ni) is greater than 0 and 1.0 wt % or less, wherein a content of copper (Cu) is 0.5 to 1.0 wt %, and wherein a content of molybdenum (Mo) is 0.5 to 1.0 wt %,
• wherein in the maintaining of the heating temperature, the heating temperature is 890 to 930° C., and a heating holding time is 70 to 110 minutes,
• wherein in the salt-bathing of the cam piece, a salt bath temperature is 270 to 290° C., and a salt bath holding time is 50 to 70 minutes, a microstructure of the cam piece is bainite, an amount of carbide is 5% or less,
• a tensile strength of the cam piece is 1,200 MPa or more, and an elongation of the cam piece is 2% or more.