URGENT! Need Brinell of 4150 at inner diameter of bar

[sprintcar]

Shaft is made from 4150 non-resulphurized steel, machined from a 11.5" (292mm) bar. The subject diameter is 7" (178mm) where we need to know the estimated Brinell hardness.

At the OD of this material the Brinell is typically 269/321. However, the information we have from the vendor stops at 8" (203mm) diameter with that Ultimate Tensile listed at 115ksi.

Since this part was machined instead of forged, the properties diminish closer to the center. What I need to know is approximate Brinell reduction at different diameters from the outside working inward.

THANKS!!!
I'll also post in Material Eng forum




Timing has an awful lot to do with the outcome of a rain dance.

 

[redpicker]

Depending on a number of variables, the hardness can actually increase with increasing depths. Yes, this is contrary to conventional wisdom, but you are dealing with a very large OD bar and you really won't know what happens unless you test the material.

At a 8" diameter, you are 1.75" below the 11.5" OD. With an Ultimate Tensile Strength of 115,000, I'd guess a Brinell hardness of around 241 HBW. To get a 7" diameter, you'd have to go another 0.5" deeper.

But, I doubt the Brinell diameter would change by more than 1.0 mm with only a 0.5" change in depth, so you are probably somewhere in the range of 255/229 HBW at your 7 inch diameter.

rp