High carbon steel wire with bainitic structure for spring and other cold-formed applications
OwnerAnand Bhagwat, Thomas Kellogg +1inventors
InventorsAnand Bhagwat, Thomas Kellogg, Steven Wray
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Abstract
According to the present invention, there is disclosed a heat treated high carbon or alloy steel wire and method of heat-treating the wire. The wire is produced by the steps of initially heating the high carbon or alloy steel wire to a temperature of about 1600 degrees F. to about 1800 degrees F. for between 10 seconds and 2 minutes; rapidly cooling the wire to an intermediate point temperature of between 400 to about 1000 degrees F.; holding the wire at the intermediate point temperature for about 2 minutes to about 40 minutes; and cooling the resulting wire to ambient temperature.
Claims20
A method of making a bainite wire coil spring comprising the steps of:
- a. initially heating a continuous length of high carbon or alloy steel wire to a temperature of about 1600 degrees F. to about 1800 degrees F.;
- b. rapidly cooling the continuous length of wire to an intermediate point temperature of between 400 to about 1000 degrees F.;
- c. holding the continuous length of wire at the intermediate point temperature for about 2 minutes to about 40 minutes;
- d. cooling a resulting continuous length of lower bainite heat treated wire to ambient temperature;
- and
- e. winding the continuous length of lower bainite heat treated wire into a coil spring.
The method of making a bainite wire coil spring of claim 4 wherein the step of in-process cooling the wire includes cooling the continuous length of wire to an intermediate point temperature of about 650 degrees F.
(canceled)
A high carbon steel, heat treated bainite wire coil spring comprising;
- a continuous length of high carbon steel, heat treated wire having a lower bainitic microstructure and a tensile strength of between 160 and 290 ksi, a yield strength of between 130 and 242 ksi and a high ductility as measured by reduction in area of about 35% to about 60%.
(canceled)
A heat treated high carbon or alloy steel bainite wire coil spring produced by the steps of:
- a. initially heating a continuous length of high carbon or alloy steel wire to a temperature of about 1600 degrees F. to about 1800 degrees F.;
- b. rapidly cooling the wire to an intermediate point temperature of between 400 to about 1000 degrees F.;
- c. holding the wire at the intermediate point temperature for about 2 minutes to about 40 minutes;
- and
- d. cooling the resulting lower bainite heat treated wire to ambient temperature;
- and
- e. winding the heating lower bainite wire into a coil spring.
Dependencies are inferred from the claim text.