Bearing unit made of low carbon steel

A bearing unit comprising:

• a radially outer ring comprising a radially outer raceway and a central portion, the central portion situated along the radially outer raceway;
• a radially inner ring comprising a radially inner raceway and a central portion, the central portion situated along the radially outer raceway;
• a row of rolling elements interposed between the radially outer ring and the radially inner ring;
• at least one sealing device mounted by means of interference on the radially outer ring and in sliding contact with the radially inner ring;
• and
• a plurality of second portions of the radially inner ring disposed on opposite axial sides about the central portion of the radially inner raceway and radially opposite from the at least one sealing device,
• wherein both the radially outer ring and the radially inner ring are made of a carbon steel having a minimum percentage by weight of carbon of 0.42%, and
• wherein the central portion of the radially outer ring and the central portion of the radially inner ring are heat treated by means of induction hardening;
• wherein the central portion of the radially inner ring comprises a hardness of between 55 HRC and 62 HRC over a depth SImin of between 10% and 20% of a diameter (SΦ) of the rolling elements.

A bearing unit comprising:

• a radially outer ring comprising a radially outer raceway;
• a radially inner ring comprising a radially inner raceway;
• a row of rolling elements interposed between the radially outer ring and the radially inner ring;
• at least one sealing device mounted by means of interference on the radially outer ring and in sliding contact with the radially inner ring;
• an outer induction hardened central portion defined within the radially outer raceway;
• an inner induction hardened central portion defined within the radially inner raceway;
• a plurality of second portions of the radially inner ring disposed on opposite axial sides about the first inner induction hardened central portion of the radially inner raceway and radially opposite from the at least one sealing device;
• and
• a plurality of third portions of the radially inner ring, disposed on opposite axial sides about the inner induction hardened central portion of the radially inner raceway, and axially outside of the plurality of second portions, wherein the plurality of third portions have a hardness of between 50 HRC and 62 HRC,
• wherein both the radially outer ring and the radially inner ring are made of a carbon steel comprising a minimum percentage by weight of carbon of 0.42%,
• wherein the plurality of second portions comprise a hardness of between 55 HRC and 62 HRC over a minimum depth of 0.1 mm,
• wherein the outer induction hardened central portion of the radially outer ring and the inner induction hardened central portion of the radially inner ring have a hardness of between 55 HRC and 62 HRC over a depth of between 10% and 20% of a diameter SΦ of the rolling elements, and
• wherein an axial length L of the second portions is equal to
• L=(Kmin−R)/2
• with
• Kmin=K1+1 mm
• where Kmin is an overall axial length of the first central portion of the radially inner ring and of the second portions of the radially inner ring, and K1 is an axial length of the radially outer ring.