Euro gear steels vs. AGMA 2001 material cleanliness grades 4

[geesamand]

I am not a gear guy, but I work with one. Is there a practical way to cross reference ANSI/AGMA 2001 Grade 2 material cleanliness against Euro steel specs (i.e. 4320H for 18CrNiMo7-6)?

My gear guy insists that all of our material, even when using a euro vendor, must have Grade 2 cleanliness to ensure adequate strength. Euro gear steels aren't tested to this spec. GG insists that grade 2 certification is necessary to handle the load. But I'm also of the understanding that the proposed euro steel has very similar material properties. For big orders we have forced the vendor to test to confirm Grade 2. We have not found the euro steels to fall short of this spec.

But for one-off jobs, testing for Grade 2 is prohibitive in cost and lead time. (It's not easy to be globally competitive when US and non-US specs are different)

 

[SwinnyGG]

You're looking for ISO 6336-5, this is the comparable document to AGMA 2001. European vendors will be familiar with this document.

6336-5 MQ is the grade approximately equivalent to AGMA 2001 Gr 2. 6336-5 ME is approximately equivalent to AGMA 2001 gr. 3, etc.

 

[tbuelna]

AGMA 2001 Tables 7 thru 10 list cleanliness requirements for different steel heat treatments (thru hardened, induction/flame hardened, carburized, nitrided). Grade 2 cleanliness is "AMS 2301 or ASTM A866, (no certification required)". Grade 3 cleanliness is "AMS 2300 or ASTM A866, certification required". Steel cleanliness mostly affects fatigue life and/or reliability rates. The allowable stress values listed in the standard are based on 10^7 cycles, 99% reliability, and unidirectional loading. There is also a notation that the Gr.2/Gr.3 cleanliness requirements only apply to the material around the gear teeth.

AMS 2301 is an "aircraft-quality" magnetic particle inspection procedure. AMS 2300 is a "premium aircraft-quality" magnetic particle inspection procedure. AMS 2301 and AMS 2300 are requirements for raw material, and both reference ASTM E1444 mag particle test practices. AGMA 2001 lists ASTM E709 for Gr.2/Gr.3 mag particle inspection of finished gear teeth.

4320H air-melt quality steel is equivalent to AMS 6299. An example of two different cleanliness quality levels of the same steel alloy is AMS 6415 (air-melt 4340) and AMS 6414 (vacuum-melt 4340). AMS 6415 conforms to AMS 2301 cleanliness standards, and AMS 6414 conforms to AMS 2300 cleanliness standards. If it is available, a vacuum-melt quality raw material will easily meet the AGMA 2001 Gr.2 cleanliness requirements. For a one-off job, the added cost of using a vacuum-melt quality material in place of an air-melt quality material should not be prohibitive. Another option for a one-off job would be ordering a piece of commercial grade 4320H with a requirement for mag particle inspection to AMS 2301 requirements only in the area where the gear teeth will be located. Also remember that AGMA 2001 Gr.2 requires a mag particle inspection of the finished gear teeth to ASTM E709 with the acceptance criteria listed.