What temperature will give good brittle fracture for A36 steel?

[knowlittle]

I have a demonstration to do. I need to show ductile brittle transition with Charpy impact tester and structural steel. A36 type. 10mm x 10 mm x 50 mm with V notch.

How low should I go in temperature to show a noticeable change in fracture morphology (to naked eyes and also under microscope)? I can go down to -20 deg C with my little recirculating bath. But in order to go lower, I need to borrow a chiller from another group. Thanks.

The other temperature will be room temperature, say 25 deg C.

 

[unclesyd]

Acetone and dry ice will give you -78C which should change the fracture morphology of A-36 CS.
Some A-36 will take -20 and show a ductile fracture.

 

[knowlittle]

Thanks for the info. I will keep acetone+dry ice+A36 as Option 1. What kind of steel will give brittle fracture at -20 deg C? I would like to present 2 choices for my management to choose from. Thanks.

 

[metengr]

The second steel should be one that contains noticeably higher carbon content in comparison to the A 36, like 1045 or 1060 carbon steel bar or plate that is not heat treated.

 

[knowlittle]

Thank you, gentlemen (or ladies) for your help.

 

[JStephen]

Wonder what plain ol' A615 rebar does...