A182 F6a Class 1

[HakiNoir]

Hi folks,

I need to form, machine and weld A182 F6a Class 1 and I am wondering which HT would have better manufacturability (Forming, Welding, PWHT , Machining, etc.):
annealed, normalized and tempered, or tempered (as identified in A182)?

This part will be welded to 410 QT steel.

Appreciate if you can share your ideas/experiences!

Thanks,

 

[metengr]

For this material and depending on part size and geometry, I would form, weld, heat treat per A 182 for normalize and temper, and final machine.

 

[HakiNoir]

Thanks metengr.
These are tight tolerances rings (13 mm th.) TIG weld with Inco-82. We plan to use no/less preheat to avoid distortion if we can. Just wondering why annealed one would not be appropriate?

 

[metengr]

HakiNoir
Thanks for the additional information regarding the tight tolerances, and use of rings. My question is what strength level do you need in service? This will determine final heat treatment condition. I see very little annealed 410 stainless steel in service. Most of the material is supplied and used in the quenched and tempered condition. You might want to re-consider use of preheat. This is probably the most significant variable to ensure reduced cracking when welding 410 stainless steel.

 

[HakiNoir]

Metengr:
There is a PWHT cycle (~650 C)after welding as the counter part is Quench/Tempered 410. Also, the strength of these heat treatment conditions were stated the same on A182! which makes me to ask this question. The spec just asked for F6a class 1. Whats your thought on this?
Regarding preheat: I will do some pre-testing but I agree with you that we will ended up with some preheat.
Thanks.

 

[metengr]

My guess is that the material under A 182 would be specified as normalized and tempered. Welding would be performed and PWHT as you stated.

 

[HakiNoir]

Thanks.
Comparing A182 F6a Class 1 with A276 410 mechanical properties (both Y/T: 40/70 ksi), I believe F6a prop. mentioned in A182 is more close to Annealed condition. Although it mentioned as Min requirement.

 

[metengr]

Yes, Class 1 would be annealed (lowest strength). I go back to what I mentioned earlier, you have 410 Q&T being joined to A 182 material, which is being specified as Class 1, why would you use annealed material recognizing the 410 Q&T being joined will be higher strength?

 

[HakiNoir]

Exactly that is my point! The customer specified this and now I am struggling to see if there is a difference in F6a Class 1 conditions (normalize and temper, temper, or annealed - as specified in A182) which gives me a better match for welding with Inco 82 to 410 Q&T.
Considering all these HT conditions have same mechanical properties, I don't see a difference in welding,machining and cold forming (to form the ring), do you?

 

[metengr]

The Class 1 will only be supplied as annealed with 70/40 (UTS/YS) as you stated above. The 410 Q&T or (T) will be supplied under A 276 as a minimum 100/80 (UTS/YS). In general, forming and welding will be similar with the exception that PWHT for the weld region will need to be performed 50 deg F below the final tempering temperature for the A 276 410 material to avoid further softening. The annealed material (F6a, Class 1) will have a heat affected zone that will be tempered during PWHT.