elements to increase the impact test

[alanisphoenix]

Hello,
For a carbon steel, how elements /structure is the best to obtein a good impact test result at -20 / -40ºC.
We melt a steel with target values aroung C=0.20 Mn=1.50 Si<0.30 V=0.12 after normalizing (ferrite and perlite with a grain size around 9) but the impact test at -20ºC is not more than 50J.

How I can increase those values?

Thank you

 

[mrfailure]

I would look at heat treatment first before I messed around with composition.

 

Don't overthink it by going off-road and designing a steel from scratch. ASTM standards should point you in the right direction for the entire gamut of product forms. Look at some MTRs of steels meeting your target requirements.

For carbon steel, normalizing, with sulphur below 0.010% should get you good impacts at -40°C. The steelmaking method also comes into it.
Avoid spicy elements like V and Nb.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[arunmrao]

This is not the age of Alchemy. Adopt some suitable standads that meet your service requirements. Following an International standard will bring greater acceptance for your products.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

 

[alanisphoenix]

ironic metallurgist
yes you are right..but it is a cliente requirement S=0.020-0.030.. i know S is not good for impact test.. that's why i have to do something to minized the Sulfur. V>0.12 is also a requiremet.. i can not do nothing with it.
The standards always are wide in composition
I have read that the S bad influence can be minimized with Mn.

Has ASTM some standars for carbon steel like have the European ones? For mechanical use? with Yield >50ksi? I know the A106, A333, A105, A519.. but no one have a steel like S355J2H (EN 10210-1) or like 20MnV6 (S460NH)..etc.

 

[bobjustbob]

How is the steel being made?
How is it being deoxidized?
How is the steel being formed?
You stated that the heat treatment is normalized. Is that per the clients specification?
What mechanical properties are you trying to achieve? Tensile/Yield and impact.
What form is your test coupon?
What is your nitrogen and oxygen content?

Bob

 

More fundamentally, what is the problem you are trying to solve?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

In addition to the comments provided, You did add Al for fine grain melting? While V will provide fine grain melting, Al should be added as well.

 

[alanisphoenix]

How is the steel being made? electric arc furnace - seamless pipes
How is it being deoxidized? Al-Si fully killed

You stated that the heat treatment is normalized. Is that per the clients specification? yes

What mechanical properties are you trying to achieve? Tensile/Yield and impact. Yield >450 Mpa Tensile >600Mpa, elsong >17% impact test -20ºC, 65 j average

What form is your test coupon?longitudinal roud 14mm OD (according to EN /DIN) - long. impact test Charpy 10x10

What is your nitrogen and oxygen content? N<0.012 O<0.005

Quality S460NH acc to EN 10216-3


In addition to the comments provided, You did add Al for fine grain melting? While V will provide fine grain melting, Al should be added as well. Yes Al >0.020 (according to the norm)

THANK YOU

 

[bobjustbob]

Your nitrogen looks like a specification. What is the actual nitrogen content that you typically see in your steel?

Bob

 

Not surprised that impact test values are low when you normalize a Nb-bearing steel.

Once again, what is the problem you are trying to solve?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

With the high S and V contents required, you will have a hard time meeting your absorbed energy requirements. Small quantities of Ni (0.5%) and Mo (0.15%) may aid in obtaining your requirement. Nickel-Manganese-Mo steels can readily meet your tensile requirements and have had good low temp impact properties.

 

Correction:
Not surprised that impact test values are low when you normalize a V- Nb-bearing steel.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."