Looking for a divot resistant material

[musashi99]

We are testing load cells here. In the process we place a load on a dead weight tester. The dead weight tester has sperical radius contact point. Next comes a disk it has parallel loading surfaces. Then the load cell (the load cell also has a sperical contact point).

During the testing process the disk is contacted by the dead weight contact point on one side and load cell on the other. In this particular case the dead weight was set a 10k lbs for three cycles and 20k lbs for three cycles. After this procedure the disk has divot about .250” in diameter and .0006” deep.

The disk is 1.5” in diameter and 1” thick. It is 17-4 Ph aged at H900.

I am looking for recommendations for a better material and heat treating for this application that will resist divoting.

We are spending a lot time maintaining this equipment (we surface grind them once a divot appears). Would like to reduce the maintenance if possible.

 

[EdStainless]

let's see, 20k lbs on 0.25" diameter is about 400ksi. You would need something with a compressive stress higher than this.
If you did use something hard enough, then you would be flattening the contact point.

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[Carburize]

How a about a disc of through-hardened 52100 as used in some bearing races?

 

[CoryPad]

How about tungsten carbide, similar to the spheres used for hardness testing (Rockwell, Brinell, etc.)?

Regards,

Cory

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

 

[EdStainless]

I don't think that he really wants to prevent this. If he does prevent this then the contact points will develop flat spots. This could hurt the accuracy of the load cells.

If you reall want to stop this you should use just about any grade of tungsten carbide. I would suggest that it have a plain steel ring heat shrunk around the OD of it in order to portect the edges from chipping or cracking.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm