Comparison of Properties of Nitinol and Stainless Steel



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In many cases, Nitinol is substituted in an application which has traditionally used stainless steel. In most cases, the Nitinol is substituted to take advantage of its unique superelasticity or shape memory capabilities.

   
 

Property

Nitinol

Stainless Steel

Recovered Elongation

8%

0.8%

Biocompatibility*

Excellent

Fair

Effective Modulus**

approx. 48 GPa

193 GPa

Torqueability

Excellent

Poor

Density

6.45 g/cm3

8.03 g/cm3

Magnetic

No

Yes

UTS

approx. 1,240 MPa

approx. 760 MPa

CTE

Martensite - 6.6 x 10-6 cm/cm/deg.C

17.3 x 10-6 cm/cm/deg.C

 

Austenite - 11.0 x 10-6 cm/cm/deg.C

 

Resistivity

80 to 100 micro-ohm*cm

72 micro-ohm*cm

 

* Please see Biocompatibility of NiTi for more information.

** The modulus of Nitinol is highly non-linear, and it is not nearly as stiff as stainless steel. Please see Introduction to Shape Memory and Superelasticity for an example of a superelastic Nitinol stress-strain curve.