11L17 for Crimping application? 1

[ThirdString]

We are trying to design a hydraulic unit that gets sealed by a threaded cylinder forming a crush fit with a base. 12L14 is the material we are starting from for the base, as it is good for crimping from what I have been able to find. However, 12L14 is not standard in a flat bar, only rounds. We would like to move to something that is more standard so we don't have to rely on mill runs, but 12L14 is the only common steel I have seen that specifically mentions it is good for crimping.

So I have 2 questions: Does 11L17 crimp as well as 12L14? And more importantly, how can I identify whether a material would be good for a crimping application? Some people have recommended 1018 as well, and I'm sure there are other options. If I can make a determination on my own, that would be better than having to ask each time it comes up!
Thanks!

 

[CoryPad]

Neither 11L17 nor 12L14 are good for applications that require "crush" or "crimp". These alloys are formulated to make them easy to machine. They have reduced formability relative to a regular steel like 1018. Actually, a lower carbon steel like 1008 would be even better for forming, though it may have lower strength.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ThirdString]

Cory,
Thanks for the response. Strength is not our biggest concern with component, so we might be able to go down to the 1008. I will have to check into that option.
Any chance you can explain how to determine what alloy is better for crush/crimp applications? I'm guessing experience, but I would think there is some mechanical property of the steel that is key?

 

[swall]

As Cory said, the free machining steels are bad for crimping. This is due to the high inclusion content. So stay away from any 1100 series or 1200 series steels. With the plain carbons steels (i.e. 1008), the lower the carbon, the lower the yield strength and the better the formability, in general.

 

[CoryPad]

Crimping is a forming operation. This requires plastic strain from the material. The routine measurement for plastic strain capacity is Elongation during a tension test. So, you could look at a site like MatWeb (

http://www.matweb.com)

and look at the Elongation values reported. Here are some sample data:

1008: 30 %
11L17: 22 %
12L14: 22 %

MatWeb only lists "typical" values, which are not necessarily what a supplier will guarantee, and not necessarily indicative of variations that can be expected from mass production.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ThirdString]

Cory,

Thank you again, that is exactly what I was looking for!

 

[unclesyd]

In addition to the information provided by CoryPad there is another possibility. You might want to check on the deep drawing steels to provide excellant ductility for crimping.