improve charpy in ambient temperature

[Vinoramesh_26]

hi ..what is the temperature of hardening to get charpy 30 joules in ambient temperature in 24 c>>.
charpy have to get min 30 joules>>>>
so can explain what temperature have to raise how many hours and holding how many hours ...
sumore the goods im doing is water quenching then have to temper 200 c for 8 hours or more..
the charpy result i get on this in ambient temp 24 c is 25joules in minus 40 c is 17joules..
supposed have to get charpy in ambient temp is minimum 30 joules and in minus temp 40 c is 22 joules..
any method?

 

[weldstan]

Chemistry of steel?

 

[Vinoramesh_26]

Carbon is 0.28 percent

 

[EdStainless]

Just a plain mild steel? Low Mn? No Cr or Si?
Did you Q&T?
Raise the tempering temp.
It will lower your strength but improve toughness.

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P.E. Metallurgy, consulting work welcomed