grade 3 ASTM A333 2

[alanisphoenix]

Hello,
which is the usual heat treatment for the grade 3?
i'm doing some tests with the samples normalized and tempering, but the impact test values at -101ºC, are quite low (about 5 to 12 j)
Any idea to increase this values? Maybe adding more Nickel to the steel? the Ni on the heat is quite close to the minimum requested by the norm.
thank you

 

[metengr]

What is your tempering temperature after normalizing? The usual heat treatment at least for normalizing is in ASTM A 333, see 4.2.

 

[alanisphoenix]

Thank you for your quick answer!
yes tempering at 600ºc, after normalizing.
ASTM A333 gives too many options... we had problems also with the normalizing, so we decide to do Normalizing+tempering , but the values are quite close to the minimum and even sometimes lower that 14j
so i'm trying to find a solution with the heat treatment and maybe with some variation at the chemical composition, increaseing a bit the Ni content and decreasing the S to the minimum (<0.005)
i'm a bit lost with this grade

 

[metengr]

More information is needed to help you. Who is actually doing the heat treatment for compliance with the ASTM/ASME 333 Grade 3 material specification? What do you mean you had problems with normalizing?? You normalize above 1500 deg F followed by tempering at 625-650 deg C. I have no idea of the material thickness, which may factor into using rapid cooling or liquid assist cooling as part of the normalization heat treatment.

 

[alanisphoenix]

we have problems with wall thickness higher than 0.5 inch (12.5mm)
We are doing now a normalizing at 1680ºF (coling by still air) and tempering at 1130ºF (cooling by still air).

i know that some years ago we did only normalizing, but i can not find enough information to know why we decide to add a tempering process.

Thnak you for your help

 

[metengr]

Your normalization temperature is too high for this Grade, which will effect grain growth. It should be 1500 to 1575 deg F. The elevated nickel content is what drives increased toughness and hardenability with a normalization heat treatment. In turn, it also promotes austenite so your lower critical transformation temperature is not as high in comparison to typical carbon steels or even Grade 6.

 

[weldstan]

Thank you metengr. So many people think 1650 F is a standard normalizing temp. for any carbon and low alloy steel.

 

[alanisphoenix]

ok metengr i will do some test normalizing at 850ºc, and tempering at 610ºC.
Do you think that quenching (and tempering)the samples i will obtain better values for thick wall thickness?

thank you so much for your help and for sharing your knowledge

 

[metengr]

Your welcome, weldstan.

alanisphoenix;
For the wall thickness at 1/2", tempering may not be required with cooling in still air. This is where trial and error are on your side to obtain favorable results. I would normalize first and CVN impact test. If the results are favorable you stop. If not, the next batch I would more rapidly cool with fans and temper at 650 to 675 deg C and see how the CVN values compare.

 

[alanisphoenix]

i will follow your instructions.. i tell you about the results in few days. tahnk you!