Out of AISI 304L Specification for Hardness

[GrimesFrank]

I would just like to get others opinions;
I have a shop that constantly applies for concessions to me for not being able to manufacture to my specifications. (Thats another thread) This is the first time they are requesting to use a material that does not meet material specs. They don't meet AISI 304L Hardness requirements (88 HRB). CMTR's verify this.
1) Wouldn't they return their supply if their supplier couldn't meet their requirements?
2) This material is to make a simple 3/8" rod with a 1-1/8 OD x 1/8 t ring welded on top. A cable runs back and forth through the ring. I plan on accepting the material (97 vs. 88 HRB), the increased hardness doesn't seem like it would affect my part. Any opinions?

I may be biased against this company since I always have to review some sort of concession they want. Anyone think I am overreacting?

 

[Metalguy]

Sounds like they may have received some slightly cold-worked stainless instead of fully annealed. Does your application require a lot of corr. resistance?

"When the Eagles Fall Silent
The Parrots Start Jabbering".

W. Churchill

 

[unclesyd]

IMHO I think it is a little much to ask for a hardness spec on any worked 304L material except fasteners or a call out such as 1/2 hard without specifying that the material be quench annealed. There there always some variation in hardness just due to SS being SS. In most cases hardness is a range. In your case there isn't much difference in Rb88 and Rb97 being on the high end of the scale.

How are you specifying the material?

What is the material, bar, rod, etc.?

Was Rb88 a minimum or maximum?

 

[EdStainless]

RB88 for fully annealed product is easy, but obviously your assembly isn't annealed after fabrication.
Why might higher hardness hurt you? In this range it will haveno impact on corrosion resistance and you will still have plenty of ductility and toughness.

When you buy small quantities it can be very difficult to get what you ask for. It is even difficult ot get the same thing twice.

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[GrimesFrank]

Thanks guys, I wasn't so much concerned about the technability (New word!!) of the situation I am in.....I agree there is sufficient ductility/toughness. The part is fully immersed in demin water, I don't see the corrosion being affected appreciably.

Good point unclesyd, the dwg did not specify cold work / annealed so I can't be picky can I? This is not even a concession as I see it then. Their upper limit could have been like RC40 right? Guess I got caught up in accepting another concession.

Thanks for knocking me off my engineer's pedestal.

 

[unclesyd]

The devil is in the details.

My reply didn't have that intent, but was an attempt to convey the premise that the details can severely restrict you and increase your cost disportionate to the gain. Under the current supply situation one needs to look around and see what's available that will do he job at hand. Have in mind what can substitute and stay within your design parameters.

Metal suppliers today like for you to tie them down as all they can see is $$$$$$ + a surcharge. Make sure you plan ahead on procurement especially for small quantities even if you have to get preproject money to get things on order instead of having the order expedited.

 

[Metalguy]

>"The part is fully immersed in demin water, I don't see the corrosion being affected appreciably."<

As long as the service temp. is not high you should be OK. But slightly cold-worked 304/316 and the L versions will develop IGSCC fairly easily under stressed conditions if the demin. water is way up around 600+F. Probably not your case tho.


"When the Eagles Fall Silent
The Parrots Start Jabbering".

W. Churchill

 

[GrimesFrank]

Metalguy,
Nope, nowhere near 600ºF....more like 150ºF. Spent Fuel Pool.

UncleSyd,
Sage advice. I wish more of my colleagues would think of these things, I'm probably the most frugal, when it comes to designing non-safety related parts.

As a related side-rant do you work in an environment where your colleagues want to weld everything but two fasteners would've been sufficient?