How Do We Change The Shape Of Nitinol Memory Alloy?

Nitinol Memory Alloy is a metal made of nickel and titanium that can be deformed by heating. It is widely used in the medical, aerospace, jewelry and other industries. So why do we rarely publish or see detailed instructions and specific steps for setting the shape of nitinol wire on the Internet?

One of the most common questions we often get from end customers in our daily work. Obviously, this is a complex and meaningful thing. If the specific parameters and application guidelines of the product itself can be published and strictly followed, it will bring great guidance and help to our aerospace, industry, life, medical and tertiary industries, because more people will use shape memory nickel-titanium alloys, and nitinol will be quickly adopted by almost all industries.

Everything will be reversed. Unfortunately, due to the high technological content of nitinol material, the transformation and complexity of martensite and austenite, it is extremely sensitive to the level and distribution of heat and the residence time. In addition, the material itself can present two properties. We test and judge which of its properties we should choose according to different application fields and design purposes to build our own models. If we change the heat treatment distribution, it may cause a particularly large change in its mechanical properties (elasticity). But there is no detailed standardized process for us to refer to and circumvent. With the accumulation of time and data, the Zhanwo Nitinol Material Team Studio customized the heat treatment curve or method for the parts according to the materials used. Otherwise, things that you don't care about during the processing, or even seemingly irrelevant things (such as increasing or decreasing the number of molds, changing fixtures, changing placement and material size, etc.) may have a very, very large impact on the properties of the parts.

In summary, although we cannot publish a specific or unified heat treatment method for Nitinol, we can publish some application guidelines for your reference:

1. Basic shape setting

To set the memory shape, you need to let the nickel-titanium alloy reach a temperature of 450-500℃ (842-932℉). If the temperature exceeds 605℃ (1,121℉), it will begin to lose the microstructure. In the Zhanwo Nitinol Research Laboratory, we use a temperature range of 450-480℃ (842-896℉). First, we design the shape we want, make the corresponding mold according to the designed shape, and then fix the Nitinol material on the mold.

2. Material selection

The phase transition temperature of niti material is inversely proportional to the nickel content. The nickel content determines the AF temperature of the material. In the Zhanwo laboratory, the AF temperature of the nitinol Memory alloy material with a nickel content of 56.1% is 0 degrees, so please choose the corresponding material according to the set temperature.

3. Heating temperature and time

Put the mold with fixed nickel-titanium material into the heat treatment equipment for heating. The influence of heating time and temperature on material properties We use 1.0mm nitinol wire material as the experimental object to show the relevant data as shown in the following table for reference:

4. Summary and Analysis

For the nitinol Memory Alloy material, the heat treatment time we used ranged from 1 minute to 5 hours. A shorter heat treatment time can make the grains smaller, resulting in better fatigue performance and higher toughness. A longer heat treatment time within the temperature range that the material can withstand can better reflect the characteristics of martensite, increase the sensitivity of the material, shorten the reaction time, and increase the phase transition temperature. If you want to know more about nitinol memory, please feel free to contact 0086-18161909780 or amybai2010@zwmet.com at any time.