Spring Steel Heat Treatment
I have a prototype that uses small spring steel tabs that act as a one way gate. They allow material to pass through the center of my assembly by flexing out of the way in one direction, and if the material reverses, the tabs will be positioned in a way that they will act like barbs, and will dig into the material, preventing it from backing out.
I don't know too much about spring steel and how heat treating it works, but I had used 1095 (for edge retention), and had it heat treated to low 50s RC. The barbs worked, but under high load they all cracked. It seems they buckled. There isn't much room for them to bend, so it appears it didn't take much deflection to break them. Can anyone offer me some advice on what I need to do to prevent them from cracking? I'm assuming I need more of an annealing process to keep them flexible, but will that ruin the spring properties? Any suggested reading I can do?
I can't go too far into detail about it, but I will try to answer any questions without giving away too much info on it.
Posted Aug 26, 2021, 3:56 PM UTC
I think you have a conflicting requirements. 50s RC can’t be flexible or ductile anymore.
Since I don’t know much about the detail of your design, but what I can suggest is localized heat treatment. So a certain area remains as resilient while the other area can be hard.
I felt the same way when several people had suggested I go that high. As for localized heat treating, I think that is going to be the route to go. That'll keep the tip hard , but allow the rest to flex.
My proof of concept has worked great, but it just breaks too easily. What would the process I need to specify to allow it to remain flexible? Just annealing it? Is there a specific temp range I should have that called out to? I'll clarify with my vendor what I need done, I would just like to have an idea of what I'm talking about before I reach out.
Heat treatment in metal components is a specialty area and oftentimes it can be proprietary. Normally you just specify the hardness and its area. You don’t control the detailed process unless you come up with a better or specific method. I recommend to talk to a heat treatment specialist or a company for your application.
Define flexible. Are we talking ductile or yield strength? Or stiffness?
I understood that the snap feature has to come back (flexible) after it gets collapsed during the insertion. Which means whatever the collapsing amount the material shouldn’t enter the yield point and remain elastic. (Spring back)