what steel allow to use for load test fixtures, any advice?

[sparollina]

I've inherited an antiquated materials testing lab at university. I intend to renovate a 1958 Reihle Fs 60 load tester.

In doing so, I wish to machine new fixtures. Specifically, the machine's load capacity is 60,000lbs. I intend to exert this, in tension on a 100k load cell w/ 1.75" thread F. What steel allow(machinable) should I use to make the threaded fixture to afix the load cell to the load tester?

Thanks!

 

[btrueblood]

Stress = force/area

60,000 lbs / [(pi / 4 ) 1.75^2] gives roughly

24,950 psi.

Which is pushing it (well above fatigue strength of) mild steel.

Use something in the range of 50 ksi yield strength, to be conservative.

The nice thing is, you can test the bar stock you made your fixtures from, once you've made the fixtures...

 

[EdStainless]

We have used 4130 and 4330 for fixtures, usually aiming for:
100ksi min yield
125ksi min Tensile
15% min elongation

At this strength you can buy heat treated bar and then machine.

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