Jominy Spec on 8620

I have received a drawing with material being 8620. Also have a spec for "32-38 Jominy @ J4". Can I assume this to mean that using the standard Jominy test, the Rockwell hardness (C-scale) 4/16 or 1/4" away from the water quenched end should fall between 32-38 Rc?

Any help would be appreciated.

 

[TVP]

SAE J1268 Hardenability Bands for Carbon and Alloy H Steels gives the following range for alloy 8620H:

"J" distance HRC
sixteenths
of an inch max min

4 41 27

So, the range that you have been given of 32-38 HRC is a subset of the requirement for SAE J1268. You can obtain a copy of this standard from SAE at

http://www.sae.org

.

 

[bilge]

A post-script to the previous response.

These days the Jominy curve for a steel can be calculated from knowledge of the steel's actual (not spec'ed) composition and its austenitic grain size. See the current ASTM spec for the technique.

 

[lgearhart]

Just to add to TVP's and Bilge's fine postings:

I would interpret the 32-38 as an additional requirement on the steel. As TVP pointed out, the standard callout for 8620H (8620 with guaranteed hardenability) is 27 to 41 at the 4/16" position on the Jominy bar. (Hallen, your interpretation was correct.) Hence to get a tighter 32-38 you need to get the steel company to refine the composition & grain size, or buy what a distributor has that meets the requirement.

ASTM A 304 is the ASTM analog of J1268, and the Jominy hardneability test specifications are ASTM A 255 and SAE J406. Of interest might be the "restricted hardenability" bar specifications, ASTM A 914 and SAE J1868, which has a Jominy hardenability of 30 to 38 at the 4/16" position for 8620RH. Not quite, but closer to your mark...

Good luck!

Lee