The difference between ASTM A105 flange and A105N flange

When we produce carbon steel flanges A105 material,sometimes customer request ASTM A105 material,sometimes it is A105N material.What is the difference between the ASTM A105 steel flange and ASTM A105N steel flange?

ASTM A105 steel flanges packed in our factory

ASTM A105 and A105N steel flanges have same raw materials,same steel grades,but they are not same,they have different heat treatment requirement.N means Normalization heat treatment,and A105 flange haves no heat treatment requirement.

Finished ASTM A105N Steel Flange

That means the A105N flange is one kind of A105 flange.But A105N flange have a better mechanical properties than regular A105 flange,better strength and better performance in low temperature service.(What is ASTM A105N flanges?)

In a word,the ASTM A105 flange and ASTM A105N flange have a same chemical composition,but the ASTM A105N have a better mechanical property and usually used in critical situation.