How Do We Set The Shape Of Nitinol Alloy?

Nitinol alloy is a smart metal made of nickel and titanium. It not only deforms by heating, but also undergoes shape memory changes when powered or heated, that is, it returns to its original shape. These excellent characteristics make it widely used in 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 metal on the Internet?

This is also one of the most common questions we often hear from end customers in our daily work. Obviously, this is a complicated and meaningful thing. If the specific parameters and application guidelines of the nickel titanium 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 Nitinol alloy, and it will also be quickly adopted by almost all industries, such as paragliders, jewelry, thermostatic showers, etc.

Everything will be reversed. Unfortunately, due to the high technical content of Niti alloy material, its transformation temperature of martensite and austenite and its complexity, it is extremely sensitive to the level and distribution of heat and residence time. In addition, the material itself can present two characteristics. We test and judge which characteristics should be selected to build our own models according to different application fields and design purposes. If the heat treatment distribution is changed, its mechanical properties (elasticity) may change particularly greatly. But there is no detailed standardized process for us to refer to and circumvent. With the accumulation of time and data, the Nitinol alloy Material Team Studio of Zhanwo Metal has customized the heat treatment curves or methods for different parts according to the materials used. Otherwise, some things you don't care about in the processing process, even seemingly insignificant things (such as increasing or decreasing the number of molds, changing fixtures, changing positions and material sizes, etc.) may have a very large impact on the performance of the parts.

In summary, although we cannot publish specific or unified heat treatment methods for shape memory alloys, we can publish some application guidelines for your reference:

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

The phase transition temperature (AF Temperature or relative transition temperature) of Nickel-Titanium 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 NiTi memory alloy material with a nickel content of 56.1% is 0 ℃, so please select the corresponding material according to the set temperature.

Put the mold with the NiTi metal material fixed in the heat treatment equipment for heating. The effect of heating time and temperature on material properties: We use 1.0mm NiTi wire as the experimental object, and the relevant data are shown in the following table for reference:

For the shape setting of nitinol alloy material, we use a heat treatment time range of 1 minute to 5 hours. Shorter heat treatment time can make the grains finer, thus obtaining better fatigue performance and higher toughness. Within the temperature range that the material can withstand, extending the heat treatment time can better reflect the characteristics of martensite, improve the sensitivity of the material, shorten the reaction time, and increase the phase transition temperature. If you want to know more about the shape setting of NiTi memory alloy, please feel free to contact 0086-18161909780 or amybai2010@zwmet.com.