Shape memory parts of 60 Nitinol
AssigneeNitinol Technologies, Inc.
InventorGerald J. Julien
Life of this patent
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Abstract
A process for making Type 60 Nitinol with shape memory effect from hot-worked material, such as hot rolled Type 60 Nitinol sheet or plate, includes heat treatment to a temperature of 600° C.-800° C. and holding the material at that temperature until the temperature has equalized throughout, and then heat soaking at that temperature for about 15 minutes. The material is then quenched immediately from that temperature, to a temperature below 300° C. This heat treatment produces Type 60 Nitinol in a condition denoted “ultraelastic”. Ultraelastic Type 60 Nitinol has a shape memory characteristic having a very low transition temperature. The transition temperature can be tailored within a wide temperature range by the temperature of the initial heat treatment and subsequent rate of cooling.
Claims2
A process of making parts of Type 60 Nitinol having a shape memory effect, comprising:
- selecting a Type 60 Nitinol workpiece that has been hot-worked at a temperature of about 900° C. to 950° C. to a reduction of at least about 2% in the dimension of said hot-working;
- heat treating said hot-worked workpiece to produce said desired properties, said heat treating including heating said workpiece to at least about 600° C. to about 800° C. and quenching said heated workpiece to produce an ultraelastic part having properties of elasticity, toughness and high yield strength;
- whereby, said ultraelastic part may be supercooled to a temperature of less than −20° F. to effect a metallurgical transformation to a soft and malleable condition of less than 20KSI yield strength;
- and said supercooled part may be deformed while in said soft and malleable condition;
- and said deformed part may be allowed to warm to a temperature above about −10° F., whereupon it will spontaneously exert a restoring force tending to 11 restore said part to said pre-deformed condition.
A process of making parts and forms of Type 60 Nitinol that have shape memory and an elastic limit of at least 4% above said transition temperature, comprising:
- selecting a hot worked part made of Type 60 Nitinol;
- heating said part to a temperature of about 500° C.-700° C. and holding said part at said temperature for a post-hotwork heat soak period sufficient to attain temperature equalization throughout said part;
- and
- quenching said part at a fast cooling rate in a coolant to room temperature;
- and
- cooling said part to a low temperature to effect a transformation to a soft and ductile martensite state.
Dependencies are inferred from the claim text.