Upgrading Inconel 625 grade 1 5

[XL83NL]

We had the need to buy Inconel 625 for a project we're doing. We ended buying grade 1, since grade 2 just wasnt available in the product form we required (tubing). Upon review of ASME SB444 for UNS N06625, would it be possible to upgrade a 'batch grade 1 tubing' to grade 2 by doing a solution anneal @ ~ 2100°F? Our application runs at 700-750 °C.

 

[metengr]

XL83NL;
Yes.

 

[XL83NL]

Hi metengr. Thanks for your reply. Do you have any recommendations regarding holding time, heat up and cool down ramp? Will the solution annealing treatment not devaluate any other material (mechanical) properties?

 

[metengr]

The solution anneal should not adversely effect other mechanical properties. As far as hold time, for tubing depending on thickness I have seen 10 minutes as a solution anneal hold time once temperature is reached.

For ramp up and cool down rates, I would recommend you work with a reputable local heat treater or tube mill because this depends on furnace charge and type (batch versus continuous).

 

[EdStainless]

You do know that after the anneal you will need to straighten the tubing, and then re-do all testing, both NDT and mechanical properties.
This is very odd, any mill that makes this could have simply altered the final anneal and give you the correct material.

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P.E. Metallurgy, Plymouth Tube

 

[WKTaylor]

XL83NL...

Did You procure Your tubing per ASTM B444? NOTE: I Could NOT ID any similar tubing spec per ASME

This may/may-not be useful...

SAE AMS5581 Nickel Alloy, Corrosion and Heat-Resistant, Seamless or Welded Tubing 62Ni - 21.5Cr - 9.0Mo - 3.7Cb (Nb) Annealed (Composition similar to UNS N06625)

Per the AMS spec...

1.2 Application
This tubing has been used typically for fluid lines requiring high strength and corrosion resistance at temperatures from cryogenic to 1800 °F (982 °C), but usage is not limited to such applications.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[metengr]

NOTE: I Could NOT ID any similar tubing spec per ASME

?????

See ASME SB 444

SPECIFICATION FOR NICKEL-CHROMIUMMOLYBDENUM-
COLUMBIUM ALLOYS (UNS N06625
AND UNS N06852) AND NICKEL-CHROMIUMMOLYBDENUM-
SILICON ALLOY (UNS N06219) PIPE
AND TUBE SB-444

ASTM does not provide process details, it is expected that Manufacturer's know this and it is up to the Purchaser to trust BUT VERIFY!!!!!!!!!!!!!!!!!!!!!

 

[moltenmetal]

Just be careful given that the anneal can result in a lot of scale...it would need to be annealed in hydrogen to keep it "bright". Not sure if that affects the properties at all.

 

[EdStainless]

In production this tubing is annealed in dry high purity hydrogen (D.P.<-50C and O2<1ppm) to preserve the surface finish.
The only difference between Gr1 and Gr2 is that Gr2 is annealed at a higher temp and therefore has lower strength.
We make both of these all of the time (as do our competitors), but the chances are that distributors will have limited options.
Why do you need Gr2? It is not stabilized since it has been solution annealed.

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P.E. Metallurgy, Plymouth Tube

 

[WKTaylor]

Dohhhh... I've got-it... bad aerospace engineer...

ASME BPVC.II.B-2017 ASME Boiler and Pressure Vessel Code - An International Code

SB-444
SPECIFICATION FOR NICKEL-CHROMIUM-MOLYBDENUM-COLUMBIUM ALLOYS (UNS N06625 AND UNS N06852) AND NICKEL-CHROMIUM-MOLYBDENUM-SILICON ALLOY (UNS N06219) PIPE AND TUBE
SB-444
(Identical with ASTM Specification B444-06(R11) except that certification and test report have been made mandatory per SB-829.)

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[XL83NL]

Thanks all. Good remark on the bright annealing. Starting to get 2nd thoughts now if the bright annealing will bring me so much extra as compared to the potential disadvantages of not doing it.

Why do you need Gr2? It is not stabilized since it has been solution annealed.

Our service temperature is 700-750 °C. Grade is only allowed to 649°C as per Code. Also review section 1.1.1 of B444, which details the use of grade 2. Hence grade 2 is required.

 

[XL83NL]

PS; we'll use the tube for compression fit twin-ferruled fittings, so hardness (after annealing) is also an issue.

.. any mill that makes this could have simply altered the final anneal and give you the correct material.

Well, in the EU, it wasnt easy (better yet almost impossible) to find 625 grade 2 from a mill that usually provides quality.

 

[Dhurjati Sen]

XL83NL
What did you do finally?

 

[XL83NL]

Use grade 2. No Heat treatment of whatever method to upgrade it.

 

[Dhurjati Sen]

XL83NL
So how come you are using something between 700-750 C when it is only allowed up to 649 C as per code (as per your own threads)? I am curious.

 

[EdStainless]

If the final anneal temp wasn't high enough you can't call it Gr2, the properties are not the decider for this.

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P.E. Metallurgy, Plymouth Tube

 

[XL83NL]

Operating temperature is (far) below design, so we have a big margin on that. Some of the hottest part might never even see 650 °C. What are you gonna do when you cant source what you need and there's no alternartive? A post fabrication heat treatment to 2100 F would damage the material, so that was no option. The application is a test unit which will be disassembled frequently enough to determine any material degradation.

 

[moltenmetal]

Failure at the conditions in question is going to be related to either creep or oxidation/spalling material loss. Neither happen instantaneously. In hot equipment/piping like this, ongoing periodic inspection and replacement is the only strategy that is possible. It's not possible to just pick another, more resistant metallic material. This is what happens when people apply code thinking closed-mindedly to what inherently must be an "engineered for purpose" solution.

 

[metengr]

Well said, XL83NL.

 

[EdStainless]

Hire a sourcing person that can find the correct suppliers,
or learn how to place orders early enough.
Any mill that produces this product can make both grades.
Sometimes paying more and waiting longer is the correct option.

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P.E. Metallurgy, Plymouth Tube