Method for heat-treating steel work pieces
AssigneeSKF GmbH
InventorWolfgang Nierlich
Life of this patent
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Abstract
A method of heat-treating a work piece of high-alloy steel by hardening involves relatively briefly annealing the work piece before hardening, followed by cooling the work piece. The brief annealing that is performed before the actual hardening and the ensuing cooling results in homogeneity of the material in the microscopic range. Following the annealing, the work piece is hardened, for instance by quenching in a salt bath, to achieve a super fine distribution of globular carbides in the microscopic structure with considerably reduced size as compared to the outset state. Also, the microscopic structure created by the method of the invention has improved toughness properties as well as increased microscopic structure stability to aging and leads to a longer service life.
Claims19
A method for heat-treating a roller bearing steel work piece used in a roller bearing comprising:
- heating the work piece to a first temperature greater than about 1000° C. and less than a melting temperature of the work piece and maintaining the temperature of said work piece at a temperature equal to or greater than said first temperature for a period of time not greater than 120 seconds, and cooling the work piece after said heating to anneal the work piece and produce an annealed work piece;
- heating the work piece resulting from said cooling to an austenitizing temperature;
- and
- quenching the work piece that has been heated to the austenitizing temperature.
A method for heat-treating a work piece of high-alloy steel by hardening, comprising:
- annealing the work piece by heating the work piece to a first temperature and maintaining the temperature of said work piece at a temperature that is substantially equal to or greater than said first temperature for a period of time not greater than 120 seconds, before hardening followed by cooling the annealed work piece.
Dependencies are inferred from the claim text.