Shape Memory Alloy SMA Spring, Nitinol Wire

• Type: Nitinol
• Application: Industrial, Medical
• Technique: Customized
• Grade: GR5
• Shape: Round
• Transport Package: PP Bag, White Box, Cartons
• Model NO.: SMA Spring
• Specification: customized
• Origin: China
• Production Capacity: 50, 000pieces /Month

Product Description

The term Shape Memory Alloys (SMA) is applied to a group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Generally, these materials can be plastically deformed at some relatively low temperature, and upon exposure to some higher temperature they will return to their shape prior to the deformation.

Conditions	Cold-Worked, Straight Strain Annealed, Shape Set Annealed
Surfaces	Shiny Black Oxide, Mechanically Polished, Ultrafine Polished, Customer Specific Requirements
Size	Diameters from 0.01mm to 5 mm and above
Length	Coils or Customers' Requests
Packing	Standard seaworthy packages or as your requests

Physical Properties of Nitinol:
Density: 6.45gms/cc
Melting Temperature: 1240-1310° C
Resistivity (hi-temp state): 82 uohm-cm
Resistivity (lo-temp state): 76 uohm-cm
Thermal Conductivity: 0.1 W/cm-° C
Heat Capacity: 0.077 cal/gm-° C
Latent Heat: 5.78 cal/gm; 24.2 J/gm
Magnetic Susceptibility (hi-temp):3.8 uemu/gm
Magnetic Susceptibility (lo-temp): 2.5 uemu/gm

Mechanical Properties of Nitinol:
Ultimate Tensile Strength: 754 - 960 MPa or 110 - 140 ksi
Typical Elongation to Fracture: 15.5 percent
Typical Yield Strength (hi-temp): 560 MPa, 80 ksi
Typical Yield Strength (lo-temp): 100 MPa, 15 ksi
Approximate Elastic Modulus (hi-tem): 75 GPa, 11 Mpsi
Approximate Elastic Modulus (lo-temp): 28 GPa, 4 Mpsi
Approximate Poisson's Ratio: 0.3
Applications
SMAs have been used in a wide variety of applications spanning diverse industries. Apart from the flexible spectacle frames mentioned above, they can be used in bioengineering applications such as dental wires such as those used in dental braces, mending broken bones using metal plates, and for medical devices that help open clogged veins and arteries. They are used as wires and tubes in applications with hot fluids flowing through them. These materials are ideal as they can retain their shape even in a heated environment.
Another application of SMAs is in civil engineering. For example, they have been used in bridge structures. SMAs can dampen vibrations, hence tuning the natural frequency of various structures. This property of vibration damping has also been used in launch vehicles and jet engines. Newer lightweight alloys have also been discovered, such as magnesium-scandium that can have a variety of potential applications such as in aerospace applications and the medical industry for biodegradable self-expanding stents.
SMAs can also also used as actuators because of their ability to change shapes and have potential applications in aircraft and space vehicles because they are lighter and can help save energy compared to bulky mechanical actuators. Earlier this year, NASA demonstrated a nickel-titanium SMA actuator used in folding the outer portions of wings during flight. This change in the angle of the plane's wings according to wind and turbulence helps reduce energy use.
nother possible application of SMAs is in retrofitting buildings that are not designed considering seismic conditions. Here, the ability of SMAs to undergo large deformations with very little residual strain as well as their ability of reversible shape change with hysteresis is used. A beam column joint can be retrofitted with reinforced concrete using pre-stressed SMA wires. This significantly increases their shear strength and axial loading capacity, compared to wires that are stressed only when the concrete starts expanding.
In a latest discovery, researchers have increased the operating temperatures of high temperature SMA, from about 400 °C up to about 700 °C. They achieved this by combining four or more metals to form the shape memory alloys. One potential application of SMAs with high operating temperatures could be in decreasing airplane noise when coming into an airport. The SMAs could automatically change the size of the exhaust nozzles depending on the temperatures encountered during the various flight stages.