Which orientation will have lowest toughness?

[EdStainless]

I am dealing with hot forged bar, about 6" OD.
It happens to be 15-5PH, but this should apply to any age hardened alloy.
Which position/orientation will have the lowest impact toughness?
I can think of nine different combination to take impact bars, but I only want to take two.
Which will give me worst case?

Opinions are welcomed, if you have a good reason.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[redpicker]

Ignoring effects due to heat treating and forging, I would expect the lowest CVN values to be obtained from samples where the longitudinal axis of the specimen has a radial direction of the original bar and the notch is oriented in a longitudinal direction of the original bar. This would have the fracture crossing as few of the flow lines from the forging as possible.

rp

 

[metengr]

For forged bars and from testing requirements specified in ASTM, regardless of alloy, impact test specimens oriented in the T-L direction would be lower.

 

[EdStainless]

Do I want a transverse bar taken radially, or tangentially?
I know that I want the notch running in what was originally the L direction of the bar.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[Wrenchbender]

Hot-working in the long direction creates mechanical texture that typically affects mech'l properties, of course. Refer to Figure A5.2 in ASTM E23 for a schematic on directionality. It this respect, you have a 2-dimensional item, with a 1-dimensional 'grain' flow. I agree with the other two posts for bar orientation. Radial or tangential? Speciemn translation probably wouldn't matter a great deal, but I'd go with the v-notch at the bar centerline, simply because its where the material is worked the least. You also mentioned that the bar is precip hardened, but I wouldn't think that's especially relevant (unless overaged)since the precipitants should be homogeneous.

 

[redpicker]

I'd have to say metengr is correct.

Look at the figures A5.1 and A5.2b in ASTM E23. The T-L in A5.1 is also called Y-X, which is a tangential specimen with a radial notch. I doubt there would be much difference between this and the Z-Y orientation (S-T) in a round bar, but I think the conventional thinking has the T-L being the lowest for round bar, RCS, plate, or slab.

rp