A352 LCC Special Impact Testing

[gatchaman]

Client has special Impact Test requirement of 30J at -60C
Minimum per ASTM for LCC is 20J at -46C
We were going to use LC3 to meet requirement but issue with supplier forced us to go in another direction. So can we get LCC to meet this requirement? I've seen MTR for LCC have Energy values way in excess of 20J at -46C, so I'm thinking it may be possible to achieve the 30J at -60C but just not 100% certain because I don't know how the lower temp adversely affects the Energy value.
If LCC is no good, then I'm thinking CF3M is another alternative.

 

[metengr]

I don't see an issue provided the LCC Grade is supplied in a liquid-quenched and tempered condition to meet the 30J at -60 deg C.

 

[gatchaman]

metengr: does it have to be liquid-quenched or can it be normalized prior to being tempered?

 

[metengr]

gatchaman;
If you review the ASTM material specification you will find the recommendation for using liquid-quenching to achieve desired low temperature properties (aka notch toughness). I think you try normalization and temper if the wall thickness of the component is less than ½” and carbon content is on the lower end of the range. Cooling during normalization has to be with air movers or liquid spray.

 

[stanweld]

The requirement is at the edge of LCC capability but can be met with appropriate chemistry controls and heat treatment. You need to confirm with the casting supplier.

 

[jwhit]

Start with clean material, plate for example or AOD material if you can get it. I wouldn't just induction melt, basic arc at a minimum. Your phos and sulfur levels need to be <0.02% and other contaminants need to be low also. You don't want to start with dead metal. Carbon at .20% and Mn up near the max will help too. I have seen foundries run with intentionally high residual Ni(remaining within residual limits)to help impacts. Normalize at 1750F, Air cool, Austenitize at 1650F water quench, then temper at 1275F. Minimize transfer time from the furnace to the quench tank. If all goes well you can see 40 ftlbs + (54J) from this material at -50F/-46C. Good luck.