Need to improve Charpy Results

[Sujay9227]

Hi Guys. I need your advice. I am current working on a NiCrMo material which the mechanical property requires a 30J at 20c. This material has 3 stage of heat treatment which are Normalise@980c Harden@930c and temper at 210c. For now i only can archive a min 25 to max 28J. Can you please advice. Thank you

 

[weldstan]

Carbon content?
quench media?
thickness?
alloy content?

 

[weldstan]

Suspect normalizing temp. and hardening temp too high.

 

[MFAMET]

By reducing both temps to 1700F and 1650F, respectively, you could get the finer grains which could boost toughness. Also, by increasing the tempering temperature, you will increase the ductility and toughness but it might cost some of the material strength.