Solution annealing for Hastelloy C-276 material

[Anton Sudiantoro]

Dear All,

I have some questions related to subject above.
The background, pipe material which did a solution annealing got a crack after one year operation.
Solution annealing conducted by heated up to 1120 deg C and holding until 30 mins.
Then rapid quenching using water
Microstructure test in lab shown that twin anneal was not visible and precipitation observed in material.
1. What is the possible cause of that matter?
2. What inspection required to check the material after solution annealing process? Is it hardness check?

And other that that, basically, does hastelloy need solution annealing after welding work?

Thank yu very much in advance

 

[EdStainless]

Are you using material manufactured by Haynes? If not then this is alloy 276.
To start with I believe that 1120C is too low for this material. I know that the lit says this.
I would suggest 1200C min.
And the 30 min starts when the entire part reaches the temperature.

But no, 276 may not need to be annealed after welding depending on the corrosion in your service.
And depending on the specifications involved. If you are making pipe then in nearly all cases full solution anneal is required.
Using as-welded requires that you work to a proven weld procedure, with trained welders, and have enough corrosion and mechanical testing on weld coupons. In acid environments as welded often works well, in high Cl situation not so much.

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P.E. Metallurgy, consulting work welcomed

 

[Anton Sudiantoro]

Dear Ed,

Thank you very much for your reply.
Yes you are correct. It is C276.
I also suspects that the temp not enough during annealing. Do you have any reference source about the requirement of 1200 deg C?

And again, do you think hardness test is proper enough for making sure the quality of annealing?

 

[EdStainless]

The hot work range for 276 goes up to 1235C or so for max.
We used to anneal 276 castings 2275Fx3hr all of the time.
As far as hardness goes it is a very rough approximation, I would do a micro or tensile, at least periodically to very condition.

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