G8 astm a333, doble normalizing and temepring or quenched and tempering?

[alanisphoenix]

hello,
we are trying to manufacturing G8 according to ASTM A333. We have not any experience with this grade, so any help will be appreciated.

I have doubt about the heat treatment. This grade is so similar to the X10Ni9 (EN 10216-4), and in this standars, it says that the heat treatment depends on the wall thickness, and that the pipes could be normalizing before being Quenched and tempered
They also talk about the tempering cooling in air or in water.
So we have so many options, N+Q+T, Q+T, N+N+T..with different cooling media for the tempering

I suppose the best could be cut a sample and do some test at the laboratory ussing the different heat treatments.


And about the chemical composition, any sugestion??

thank you so much

 

[metengr]

If you are heat treating Grade 8 pipe under ASTM A 333, you have two heat treatment methods - either quench and temper or double normalize and temper per 4.2.2 of A 333. See below;

4.2.2 Grade 8 pipe shall be heat treated by the
manufacturer by either of the following methods:
4.2.2.1 Quenched and Tempered — Heat to a
uniform temperature of 1475 ± 25°F [800 ± 15°C]; hold
at this temperature for a minimum time in the ratio of 1
h/in. [2 min/mm] of thickness, but in no case less than
15 min; quench by immersion in circulating water. Reheat
until the pipe attains a uniform temperature within the
range from 1050 to 1125°F [565 to 605°C]; hold at this
temperature for a minimum time in the ratio of 1 h/in.
[2 min/mm] of thickness, but in no case less than 15 min;
cool in air or water quench at a rate no less than 300°F
[165°C]/h.
4.2.2.2 Double Normalized and Tempered —
Heat to a uniform temperature of 1650 ± 25°F [900 ±
15°C]; hold at this temperature for a minimum time in
the ratio of 1 h/in. [2 min/mm] of thickness, but in no
case less than 15 min; cool in air. Reheat until the pipe
attains a uniform temperature of 1450 ± 25°F [790 ±
15°C]; hold at this temperature for a minimum time in
the ratio of 1 h/in. [2 min/mm] of thickness, but in no
case less than 15 min; cool in air. Reheat to a uniform
temperature within the range from 1050 to 1125°F [565to 605°C];
hold at this temperature for a minimum time
of 1 h/in. [2 min/mm] of thickness but in no case less
than 15 min; cool in air or water quench at a rate not
less than 300°F [165°C]/h.

Your heat treatment method will depend on component geometry and the handling capability of the supplier. Talk to the supplier, and see what they recommend. If you are the supplier, and I was the purchaser I would require heat treatment coupons using your process capabilities.

 

[stanweld]

You only have the options defined in A-333 for Grade 8. The best option will depend on the pipe thickness and overall costs to meet the mechanical properties. Cost should favor Q&T.

 

[alanisphoenix]

thank you for your comments,
yes i have the ASTM A333, so i know about the options. "stanweld" you talk about choose the heat treatments depending on the wall thickness. Where in your opinion is the limit to choose one or the other? less that 1 inch? NNT and heavier wall thickness QT?

Any one know about a study/book, etc about this kind of steel that could be useful. I've found some interesting articles at the NIckel Insitute.
thanks again for you help.

 

[stanweld]

My experience with 9% Ni alloys is limited to plate with thickness from 3/8" to 1.5", all of which were Q&T. Be very careful in handling to minimize residual magnetism.

 

[metengr]

You can review the attached to decide on heat treatment.

http://www.arcelormittalna.com/plat...ctBrochure/ARCELORMITTAL 9 PERCENT NICKEL.pdf

 

[alanisphoenix]

thank you for your comments and your help.
the doc. of arcelor seems to be quite helpful. THANK YOU!