Section steel wire of oil ring

An oil ring for use in an internal combustion engine, having a surface treatment layer formed on at least a sliding surface thereof which makes a sliding contact with an inner surface of a cylinder of the internal combustion engine, and chemically consisting essentially of, by weight:

• 0.6 to 1.5% carbon, not more than 1.5% S i, not more than 1.5% Mn, more than 20% and not more than 25% Cr, and optionally containing
• at least one group selected from three groups consisting of a group of at least one element of Mo and W in total amount of not more than 3% of "Mo+W/2" another group of at least one element of V and Nb in total amount of not more than 3% of "V+Nb/2" and still another group of at least one element selected from not more than 12% Co, not more than 5% Ni and not more than 5% Cu, and
• balance of Fe and unavoidable impurities, wherein:
• the section steel wire has been subjected to a quenching heat-treatment followed by a tempering heat-treatment so as to have a Vickers hardness of HV 300 to HV 450, the section steel wire has a substantially H- or X-shaped cross-section, having a web portion and flange portions, which is provided by working a blank steel wire having a rectangular or square cross-section by forming longitudinal recesses on two opposite sides of the rectangular blank steel wire respectively, and a thickness ratio of the thickness of a web portion bridging flange portions to the total thickness (T) of the flange portions is not greater than 0.3, the web portion having a plurality of oil passage holes being formed by punching in a longitudinal linear row line, at least one of the opposed surfaces of the web portion being substantially flat, and wherein the following conditions are met:
• W-b.gtoreq.0.4 t,
• C.gtoreq.t,
• wherein:
• W=a specified width of the substantially flat surface of the web portion,
• b=a breadth of the oil passage hole,
• t=a height of a breadthwise wall surface of the oil passage hole, and
• C=the spacing between adjacent oil passage holes.

A section steel wire for use in an internal combustion engine, chemically consisting essentially of, by weight:

• more than 0.80% and less than 0.95% carbon, no more than 1.0% Si, not more than 1.0% Mn, not less than 15.9% and not more than 20.0% Cr, and
• optionally containing at least one group selected from three groups consisting of a group of at least one element of Mo and W in a total amount of not less than 0.5% and not more than 3% of "Mo+W/2" another group of at least one element of V and Nb in a total amount of not less than 0.05% and not more than 2% of "V+Nb/2" and another group of at least one element selected from not more than 12% Co, not more than 5% Ni and not more than 5% Cu, and
• balance of Fe and unavoidable impurities, wherein:
• the section of steel wire has been subjected to a quenching heat-treatment followed by a tempering heat-treatment so as to have a Vickers hardness of HV 300 to HV 450, the section steel wire has a substantially H- or X shaped cross-section, having a web portion and flange portions, which is provided by working a blank steel having a rectangular or square cross-section by forming longitudinal recesses on two opposite sides of the rectangular blank steel wire respectively, and a thickness ratio of the thickness of the web portion bridging flange portions to the total thickness of the flange portions is not greater than 0.3, the web portion having a plurality of oil passage holes being formed by punching in a longitudinal linear row line, at least one of the opposed surfaces of the web portion being substantially flat, and wherein the following conditions are met:
• 1.4 t>W-b.gtoreq.0.4 t,
• C.gtoreq.t,
• wherein:
• W=a specific width of the substantially flat surface of the web portion,
• b=a breadth of the oil passage hole,
• t=a height of a breadthwise wall surface of the oil passage hole, and
• c=the spacing between adjacent oil passage holes.

An oil ring for use in an internal combustion engine,.having a surface treatment layer formed on at least a sliding surface thereof which makes a sliding contact with an inner surface of a cylinder of the internal combustion engine, and chemically consisting essentially of, by weight:

• more than 0.80% and less than 0.95% carbon, not more than 1.0% Si, not more than 1.0% Mn, not less than 15.0% and not more than 20.0% Cr, and optionally containing
• at least one group selected from three groups consisting of a group of at least one element of Mo and W in total amount of not less than 0.5% and not more than 3% of "Mo+W/2", another group of at least one element of V and Nb in total amount of not less than 0.05% and not more than 2.0% of "V+Nb/2" and still another group of at least one element selected from not more than 12% Co, not more than 5% Ni and not more than 5% Cu, and
• balance of Fe and unavoidable impurities, wherein:
• the section steel wire has been subjected to a quenching heat-treatment followed by a tempering heat-treatment so as to have a Vickers hardness of HV 300 to HV 450, the section steel wire has a substantially H- or X-shaped cross-section, having a web portion and flange portions, which is provided by working a blank steel wire having a rectangular or square cross-section by forming longitudinal recesses on two opposing sides of the rectangular blank steel wire respectively, and a thickness ratio of the thickness of a web portion bridging flanges to the total thickness (T) of the web portion having a plurality of oil passage holes being formed by punching in a longitudinal linear row line, at least one of the opposed surfaces of the web portion being substantially flat, and wherein the following conditions are met:
• W-b.gtoreq.0.4 t,
• C.gtoreq.t,
• wherein:
• W=a specified width of the substantially flat surface of the web portion,
• b=a breadth of the oil passage hole,
• t=a height of a breadthwise wall surface of the oil passage hole, and
• C=the spacing between adjacent oil passage holes.