Nitinol - Nickel Titanium

ASTM F2516: Tension Testing of Nickel-Titanium Superelastic Materials

Nitinol is a binary alloy of Nickel and Titanium which gives the metal alloy special properties such as shape memory, superelasticity or pseudoelasticity, corrosion resistance and resistance to shocks. Applications of the alloy include civil structures such as bidges and building, medical uses such as dentistry and surgeries, aerospace among many others. Nitinol exhibits a shape memory attribute that allows the deformation of the metal alloy which then can return to its original shape by application of heat. Nitinol behaves like a super spring, possessing an elastic range 10?30 times greater than that of a normal spring material.

Mechanical Testing

ASTM F2516 - 4. Summary of Test Method 4.1 Using conventional tensile testing apparatus, the material is pulled to 6 % strain, then unloaded to less than 7 MPa, then pulled to failure.

Software

The ASTM F2516 testing method requires the UTM to be able to initially tension the specimen to 6% strain and then unload the specimen to ess than 7 MPa meaning both strain and stress control are critical for this test. Parameters for the test, the measurement values and the reporting should all follow ASTM F2516 procedure and report standard.

The reports for ASTM F2516 must include the following information: 9.1.3 Upper plateau strength, 9.1.4 Lower plateau strength, 9.1.5 Residual elongation among others.

Test results from ASTM F2516 testing under various conditions with use of extensometer

The details of the procedure as well as the UPS, LPS, ELr etc. can be found under section 8. Procedure of ASTM F2516