T-H manufactures three medical grades (Niti#1, Niti#2 and Niti#4) of Nickel-Titanium or Nitinol wire products available in either the cold worked (CW) condition ready for heat treatment or as straightened super-elastic (SE) wire.

Each medical grade of Nitinol material is comprised of near equal atomic weight percentage of nickel and titanium. Our most common medical grade, NiTi#1 exceeds chemistry requirements set forth by ASTM F2063 for use in surgical implants. At T-H, all incoming Nitinol raw materials are inspected to ensure they meet proprietary internal specifications for chemistry, ingot transformation temperature, material homogeneity, and microstructure. Optimized to promote an exceptionally smooth and uniform surface finish quality, all wire products utilize a proprietary single and multi crystalline diamond drawing die technology. Medical grade Nitinol wire may be purchased in the cold worked (CW) or the super-elastic condition (SE) and after the correct super-elastic heat treatment will accommodate strain up to 8% without permanent kinking at body temperature. The transformation temperatures and mechanical properties for each of our three standard grades of Nitinol are presented in the table at the bottom of the page.

Nitinol Wire Applications

Our Nitinol wire is used for many different medical and industrial applications. The table below gives some typical engineering applications for each of our standard Nitinol medical grades:

Grade	Application
NiTi#1	Guidewires, stents, stylets, forming mandrels, stone retrieval baskets, orthodontic files, etc.
NiTi#2	Ideal for applications that require a high loading and unloading plateau stresses at room temperature, cell phone antennae, eyeglass frames.
NiTi#4	Provides the best cycling performances at 37°C at body temperature.

Certification Data Package

UTS-Elongation

Upper and lower plateau stress (SE only)

Fully annealed ingot transformation measured by DSC

Wire transformation measured by Bend and Free Recovery (SE only)

Multiple test temperatures available i.e. 22°C ±2°C or 37°C ±2°C

Permanent set after straining to 6% or 8% strain (SE only)

Multiple gauge length and crosshead speeds

Chemical analysis

Nitinol Product Forms

Round Wire: 0.0127" to 6.350"

Flat Wire: Aspect Ratio: W/T ~ 12

Minimum Thickness: 0.00762"

Maximum Width: 5.080"

Turkshead: Square, Rectangular

Custom Shapes: A wide variety of shaped cross-sectional wire

Stranded Cables: 1x3, 1x7, 1x19, Materials Blends, etc.

DFT: Composites manufactured with a Nitinol core or a clad jacket

If your Nitinol product need falls outside of the standard medical grade material or the available product forms, please contact one of our sales engineers.

Surface Finishes Available

Light Oxide: (LO) Gold to Brown color - diamond drawn surface

Dark Oxide: (DK) Grey to Black color - diamond drawn surface

Black Oxide: (BLK) Shiny Black color - diamond drawn surface

Etch: (E) chemical removal of oxide layer - will retain smooth surface

Pickled: (P) chemical removal of oxide layer along with a slight amount of base metal - surface will have a rough texture

Etched and Mechanically Polished: (EMP) Chemical removal of oxide layer followed by mechanical polish - surface will have stainless steel appearance (although at >40x magnification, micro scratches will be present

Additional Services Available

Wire Cleaning: hot alkaline or alcohol wipe

Continuous eddy current analysis

Rotary beam fatigue testing

Metallurgical lab testing

X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Auger Electron Spectroscopy (AES), Scanning Electron Microscope (SEM), Electron Dispersive Spectroscopy (EDS)

How to Specify and Order Medical Grade Nitinol Round Wire

Wire Diameter

Specify Std. Wire diameter < 0.040" (4 decimal places) (Std. Wire Tolerance per ASTM A-555)

Nitinol Grade

NiTi#1

NiTi#2

NiTi#4

Condition

Cold Worked

Super-Elastic

Surface Finish

LO - Light Oxide

DK - Dark Oxide

BLK - Shiny Black

E - Etched Bright

P - Pickled

EMP - Etched and Mechanically Polished