Quick question about threaded-rod tensile test
Quick question about threaded-rod tensile test
(OP)
I am going to perform a standard tensile test on a fully threaded 5/8" rod. I had two fixture blocks made that are threaded for this bolt pattern, and the tensile tester holds onto these steel blocks when it pulls. The rod is 6.5" in length, and has a thread engagement of 1.5" on each side leaving 3.5" of material between the two fixtures. My question is, where will this threaded rod tend to break? If it breaks at the surface of the block, it will be difficult to remove the small remaining piece that is still threaded into the fixture block.





RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
Before you test cut a slot across both ends of the rod. Then when it breaks you can use a screw driver to remove a short piece.
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Plymouth Tube
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
Maybe a 0.30-0.35%C steel, heat treated with a temper high enough to just make it threadable.
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Plymouth Tube
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
So, to exaggerate slightly, if your test clamps were threaded, and were made out of some material less rigid, and overall less strong than the threaded rod, the test fixtures would bend and distort before the rod would.
Now, what are you trying to test for actually?
The threads themselves as a stand-alone failure point? If so, then your assembly needs to remove as a failure point everything except the tips and roots of the threads of the "average" rod.
The final tensile strength at failure of the (average ? minimum? Maximum? Nominal? 5 sigma deviation weakest?) rod? How will you define average rod material strength and average thread and rod dimensions? How many rods will you use to develope your std deviations and statistics? How will your tests vary based on changes in rod threads and rod dimensions, compared to rod material deviations? And, how will you tell the difference when each rod has failed?
The tensile strength of an (average) threaded rod held in place by an (average) nut tightened to an (average) torque value? After all, if a nut is held in place by tension, doesn't that tension increase the local stress in the rod-and-threads that can induce failure of the assembly? So, shouldn't you be worried about how much the assembly can hold, not how much a rod itself will fail at?
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
A-2 tool steel, machine complete, then heat treat, 60 HRc, it's distortion is very minimal.
chase the threads after, & grind surfaces if needed.
Mfgenggear
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test
Use 4135/4140. Machine the outside and drill the hole.
Q&T to some med hardness (1000F temper). Ask your heat-treater, I would aim for about 32RC.
Tap threads and use.
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Plymouth Tube
RE: Quick question about threaded-rod tensile test
RE: Quick question about threaded-rod tensile test