Patent ID: 8592050

Claim:
A piston ring, comprising: a refined steel consisting essentially of: carbon C in a range of 0.20% mass to 0.90% mass, silicon Si in a range of 0.10% mass to less than 0.60% mass, manganese Mn in a range of 0.20% mass to 1.50% mass, chromium Cr in a range of 0.30% mass to 2.00% mass, and iron Fe as a balance of the refined steel, wherein a parameter A calculated from the following expression (1) based on contents of the Si, Mn and Cr is 9.0 or less: parameter A=8.8 Si+1.6 Mn+1.7 Cr expression (1), wherein a parameter B calculated from the following expression (2) based on contents of the C, Si, Mn and Cr is 10.8 or more: parameter B=36 C+4.2 Si+3.8 Mn+4.5 Cr expression (2), wherein the piston ring has a hardness of 26 HRC to 51.2 HRC after a refining including a quench hardening and a tempering, and wherein the piston ring has a thermal conductivity of 36 W/mK or more after the refining including the quench hardening and the tempering.