Maximum Yield stress for Standard Hardened Steel dowel pins

Hello everyone,

I would like to ask if anyone could please help me with the following situation.

I am using a standard hardened steel "pull out" dowel pin from

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as a bearing shaft. I need to know the maximum load the dowel / shaft can support without taking a permanent set and/or becoming permanently deformed or bent. I need the shaft to always spring back to its original position after the load is removed.

I emailed Mcmaster, but they were not able to give the maximum Yield strength of the dowels.

Does hardening increase the maximum Yield stress? If so, is there a way to calculate or estimate how hardening affects the yield stress ?

Here is what Mcmaster said about the dowels and pin material...

"Hardened Steel- Made from hardened steel such as C1541, or 4037 and

4140 alloy steel. Core Rockwell hardness is C47-C58 (surface hardness is RC 60). Shear strength is the amount of force that the side of a pin can withstand before breaking. Single shear strength is the amount of force applied against a fastener in one place causing the fastener to break into two pieces. Single shear strength is 130,000 psi. An internally threaded tapped hole in one end of these pins lets you pull them out with a removal screw or a threaded puller such as 92330A (see page 3083 ) and reuse them. All meet ASME B18.8.2. Length tolerance is =B1.010"."

I would appreciate any advice or suggestions on how I can get a close estimate on this, and what would be a reasonable safety factor to apply. Nobody could get hurt if the device fails, but I just need it to be reliable. I have to consider several factors when choosing a shaft size, and everything fits in a tight space.

There are tradeoffs and space constraints when going to a bigger shaft, so I need to know how to estimate this in order to make the best compromise. It's desirable to use the smallest shaft diameter possible, that will support the load with a reasonable safety factor.

Thanks for your help. John

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The minimum yield strength should be used for design.

Yes, depends on the alloy and amount of hardening/cold work/etc. The more hardening/cold working/etc the stronger the material, but the ductility is generally less for a given alloy.

For a 4130 alloy steel with shear strength of 130,000 psi minimum, the ultimate strength is 200,000 psi and yield strength is 165,000 psi at room temperature.

See pages 2-20 and 2-25 here:

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Use at least a safety factor of 2.0 on yield for normal operations. Use a higher one if max loading is uncertainty. For hoisting a higher safety factor of 3.0 or more should be used.

You need to have an estimate of the maximum load the pin might see to determine that.

Reply to
Jeff Finlayson

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