| 摘要 |
<p>At least one of the paired members of hardenable ferro-magnetic steel in rolling contact, such as rolling elements or races of ball or roller bearings, toothed gearing elements, rolling mill rollers or thermal expansion bearing elements for steel bridges, is heat treated to produce in its zone of main loading an inherent prestress acting in opposition to the loading by controlling an inductive heat treatment before and after quenching in such a way that a surface zone in rolling contact is austenitized more uniformly and to a greater extent than the underlying zones before quenching to form a different amount of martensite in the two zones, and after quenching a dilatation is produced in the surface zone by inductive drawing differing from that in the underlying zones. Maximum inherent stress is produced at a predetermined distance from the rolling surface depending on the resistivity and permeability of the steel and frequency of current flowing in the induction coil. A roller not to be through-hardened (made of the steel: 1.0% C, 0.2% Si, 0.3% Mn, 1.5% Cr, balance Fe) may be cooled in a salt bath having a temperature of between 160 and 170 DEG C. followed by oil quenching between inductively heating and drawing.</p> |
