Where can I find information on "cold Weather Steel," I am not referring to "cold for

Where can I find information on "cold Weather Steel," I am not referring to "cold formed steel."

While conversing with a structural engineer from another firm the other day, he mentioned that I should consider specifying "cold weather steel" for stiffeners greater than 13 mm for a project of mine. I have not heard of this before, and was not able to find any information on the steel design manual.

I specified WT (instead of W) Category 4 for temperatures as low as -40

What I do not understand though, is why are steel plates with thickness greater than 13 mm more susceptible to brittle failure as opposed to steel plates less than 13 mm?
 

To ask a similar question, can A516 Gr 70 or A537 class 1 plate be considered a cold-weather steel? Will these materials have a charpy value at -50F?
 

Answer:

Depending on the exact steel composition and production process, a significant proportion of a hot-rolled steel section's strength can come from the surface and near-surface layer. A thinner section has a greater proportion of near-surface vs interior section. This may not be relevant for your particular manufacturer's steel section though.