Is My Nitinol Wire Training Process Correct?

[xsnachannell]

Hi I am a high school senior barely scratching the surface of Nitinol traingin and testing.
I ham currently trying to train .037 Nitinol wire but I can't seem to train it. On one occasion I placed the mold in an already heated oven around 900F and left it in for 5 minutes. Upon removal I quenched it in cold water (i can't really say what the temperature of the water was). When i removed the wire from the mold it still proved tough to straighten and when I heated it to the critical temperature I did not resume it's trained shape. Did I over stress it? On another occasion I placed the mold in a 900F oven and had a friend remove it after 10 mins they did not quench it so it was left out cooling in room temperature for roughly 2 minutes, when I came to look at it it had cracked in 2 in the mold so i quenched it and have not done any further testing with it. Please if anyone has any insight as to what i am doing wrong that would be greatly appreciated
Sincerely
Christina Channell

 

[Navin A S]

It sounds like you may be overstressing the Nitinol wire. The heat treatment process is very precise and even small changes in time and temperature can lead to different results. When heating the wire, it is important to use a thermocouple to make sure the exact temperature is reached and to monitor the entire process. Quenching should also be done quickly and in a liquid that is a few hundred degrees cooler than the temperature of the heated Nitinol wire. Finally, make sure to anneal the trained shape after cooling. This will help relieve any mechanical stresses from the training process. If you have further questions, reach out to a materials expert or research lab for more detailed information. Good luck!

 

[oswaler]

Hi Christina, thank you for reaching out and sharing your experience with Nitinol wire training. It sounds like you are on the right track in your training process, but there may be a few factors that could be affecting the results.

First, it is important to ensure that you are using the correct type of Nitinol wire for your training process. There are different grades and compositions of Nitinol, and each may have different training and transformation temperatures. It is possible that the wire you are using may not be suitable for the temperature and time frame you are using in your training process.

Additionally, it is important to have precise control over the temperature and timing during the training process. A variation of just a few degrees or a few minutes can significantly impact the results. It may be helpful to use a thermometer to accurately measure the temperature of the oven and the water used for quenching.

Another factor to consider is the stress and strain placed on the wire during the training process. It is possible that you may have over-stressed the wire, causing it to crack or lose its trained shape. It is important to carefully follow the recommended training procedures and not apply too much force when bending or straightening the wire.

I would also recommend consulting with a materials science expert or conducting further research to better understand the properties and behavior of Nitinol wire. With practice and a better understanding of the material, you will likely have more success in your training process.

Best of luck in your future experiments with Nitinol wire!