Nitinol Sheet Specifications: Composition, Tolerances, Mechanical Properties, an

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Nitinol sheet is one of the most precisely engineered materials in the modern metals industry. Because its performance depends on exact transformation temperatures and accurate mechanical behavior, every specification—from alloy composition to surface roughness—affects reliability.

For engineers, buyers, and medical device designers, understanding Nitinol sheet specifications is essential for selecting the correct grade.

Chemical Composition: Ni–Ti Balance Controls Everything

Nitinol is defined by a near-equiatomic ratio of nickel and titanium:

Nickel (Ni): 54–57%

Titanium (Ti): balance

A variation as small as ±0.1% Ni can shift transformation temperatures by 10–20°C, altering:

superelasticity

stiffness

recovery characteristics

shape-memory response

This is why high-end suppliers use ±0.02% precision.

Standard Thickness Range

Nitinol sheet is commonly supplied in:

Thin sheet:0.05–0.2 mm

Standard sheet:0.2–2 mm

Thick sheet:2–4 mm (less common)

Tolerances vary by grade:

Precision is essential for stents, surgical tools, and aerospace actuators.

Transformation Temperature Specifications

Typical values:

Austenite finish (Af):−20°C to +120°C

Martensite start (M_s):−80°C to +50°C

Applications determine the required Af:

Medical superelastic: Af = 10–25°C

Aerospace actuation: Af = 60–90°C

Industrial valves: Af = 80–120°C

Custom Af is available through controlled annealing.

Mechanical Properties

Typical values:

Tensile Strength: 895–1400 MPa

Yield Strength: 195–560 MPa

Elongation: 10–30%

Hardness: 20–40 HRC

Nitinol’s mechanical behavior is nonlinear due to phase transformation—unlike steel or titanium.

Surface Roughness Standards

Surface finish affects fatigue life and corrosion resistance.

Polished: Ra < 0.2 µm

Electropolished: Ra < 0.1 µm

Laser-cut raw edges: require additional treatment

Medical devices require mirror-grade surfaces.

Conclusion

Specifications define Nitinol sheet’s behavior. Engineers must evaluate composition, transformation temperatures, tolerances, and surface finish to ensure optimal performance in their application.