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# Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

## Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
I have a project with a customer requirement of FN between 3 & 10 for the combination of 347SS and 310SS using ER309L filler. At 1st glance, I thought that would be easy to meet since it's a common range for Austinitic SS, but looking further into it, I see threads in this forum stating that 309 & 310 both are often very stable and have zero ferrite formation. If that's the case, then the 347/310 combination could have a lower FN that I'd originally thought.

I found an online tool for the Schaeffler diagram. The resulting FN varied greatly depending on dilution. I could ask what a typical expected dilution for multipass TIG welds would be, but I'm sure the answers would start with "It depends".

What recommendations do you have for the joining of these materials so that we meet the FN requirements?

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

What is the FN of your filler? Most filler is balanced to have some ferrite so I would expect a 2-5 FN.
What about the 347? This should be a bit higher, the material that I have seen was often 5-8 FN.
Work it out for various dilutions, you may be OK even with 310 near zero.
But you PQR will be the final word.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
The project is in the future, so I don't have specific filler that I can pull up specs for to get the FN. I guess it varies by heat, because when I go to manufacturer's websites for their fillers, they all seem to say to contact them for FN info.

I've run the calculation in that link, and once I get up above 40-50%, I'm within that range. Lower than that is too high.

Yes, we can run samples at least if we don't need a new PQR.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

Another thing. Since you mentioned 347 and 310 as base metals for the DMW, what service or design temperature does the weld joint see?

Huub
- You never get what you expect, you only get what you inspect.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
I don't have specific design conditions, but a typical set of conditions is 850F & 3000 psi.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

Iirc, 309 filler is not suited for temperatures above (approx.) 350 deg C.

Huub
- You never get what you expect, you only get what you inspect.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
I'll keep that in mind. It is fairly common for our products to see the design conditions I stated, but many are used at much lower temperatures & pressures. As of this time, I don't know what conditions this material combination will see. These are just the materials a customer is asking us whether we are able to weld keeping within the FN range specified.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
What is the best resource for finding the temperature limits of these filler materials. Most manufacturer datasheets I've looked at when searching on this topic don't have it, and I didn't find in ASME BPVC SEC. II, PART C.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

I once got triggered by a client spec. One resource I could quickly find through Google is from a Dutch supplier, with English contents.
Not sure if all suppliers have such details, as this is more a service driven limitation than a welding process driven limit.

Huub
- You never get what you expect, you only get what you inspect.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

API RP 582 is always a good resource, but it is specific to chemical, oil, and gas industries.

The devil is in the details; she also wears prada.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

Spot on DVWE. Even though itâ€™s for oil and gas, it covers far more industries than that. In fact, API RP 582 covers the same temperature limit for 309 and 309L, under para. 6.2.2 c)1).

Huub
- You never get what you expect, you only get what you inspect.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

I truly don't understand why a customer would ask for ER309L for your temperature service. Quite onestly why chose 309L for the joint in lower temp service. Sometimes it's hard to tell a customer that he is flat out wrong but it can and should be done when warrented.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

(OP)
weldstan,

I mislead this discussion on the 27th @ 13:19. Please see my post @ 15:30. I threw out typical maximum design conditions for our most popular product, not fully thinking through the implications. It is very possible it is a different product with lower design temperatures. I just don't have those specifics yet.

Thanks, DVWE. We are primarily servicing the chemical industry, so API RP 582 will likely suit my needs just fine.

### RE: Ferrite number estimate: Combination of 347SS and 310SS, ER309L filler

Schaeffler diagram is NOT your source for determining ferrite content of real material, it is a design tool for welding engineers to estimate (not calculate) deposit ferrite content. It is not acceptable to use it to validate welds (i.e., QC) against tech spec requirements.

A PQR can be a useful guide but will not tell you what ferrite you actually get on the day of production welding (with possibly different materials than qualified).

The Fischer FerritScope is my go-to instrument for measuring deposit ferrite. Accept no substitutes.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

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