SA 516 grade 70 vs SA 516 grade 70N

Date 02-22-2005 14:48

The letters SA denote that it is an ASME standard, not ASTM. ASTM standards for ferrous materials are preceeded by the letter A.
So, you should look into ASME Code Section II, that contains all of the ASME standards regarding materials of construction.
In most cases, ASTM and ASME standards are identical, but sometimes are not, and hence my recommendation.
Unfortunately, I havn't got the ASME Code at hand at this moment and can't give you any further help.
Giovanni S. Crisi
Sao Paulo - Brazil

By Asim Date 02-23-2005 05:02

Basically I knew SA and A difference but could not find suffix "N" in my ASTM hand book. You are right that I may look into ASME codes.
Thank you for your post.

By metalcare (*)

Date 02-22-2005 15:48

N - indicates normalised condition.
Please check the ASTM standard A515 for detailed designation of its suffix. 60, 65 & 70 are different grades each denotes its tensile strength in ksi.

Hopefully this helps.

Muthu

By Asim Date 02-23-2005 05:05

I was also expecting the suffix N denotes "Normalised" as I had indicated in my post. Thank you for clearing my doubt.

By Bonniweldor (**)

Date 02-23-2005 15:51

My suggestion for you is that you need to understand the metallurgical reasons for why the N grade may be specified. There are services where use of a non N grade will be a violation of Code and/or susceptible to failure in service.

I c&p the following from http://64.78.42.182/sweethaven/BldgConst/Welding/lessonmain.asp?lesNum=2&modNum=4

NORMALIZING

Normalizing is a type of heat treatment applicable to ferrous metals only. It differs from annealing in that the metal is heated to a higher temperature and then removed from the furnace for air cooling.

The purpose of normalizing is to remove the internal stresses induced by heat treating, welding, casting, forg-ing, forming, or machining. Stress, if not controlled, leads to metal failure; therefore, before hardening steel, you should normalize it first to ensure the maximum desired results. Usually, low-carbon steels do not re-quire normalizing; however, if these steels are normal-ized, no harmful effects result. Castings are usually annealed, rather than normalized; however, some cast-ings require the normalizing treatment. Table 2-2 shows the approximate soaking periods for normalizing steel. Note that the soaking time varies with the thickness of the metal.

Normalized steels are harder and stronger than an-nealed steels. In the normalized condition, steel is much tougher than in any other structural condition. Parts subjected to impact and those that require maximum toughness with resistance to external stress are usually normalized. In normalizing, the mass of metal has an influence on the cooling rate and on the resulting structure. Thin pieces cool faster and are harder after normal-izing than thick ones. In annealing (furnace cooling), the hardness of the two are about the same.

By ajoy

Date 02-24-2005 05:18

To be more specific, please note that normalising is not only a stresss relieving process but primarily a grain refining heat treatment process. The temperature of normalising is always above the AC3 temperature of the subject steel. At this temperature, because of the change in the grain structure, the mechanical properties are optimised.

Iam posting this because I did not fully agree with Bonniweldor's explanation.
Regards.

By Ztitch Date 08-31-2005 17:40

Hola chavos !!!

Precisamente ahora mismo me encontraba con ese problema de cual era la diferencia entre a516-70 y a516-70N

Parece ser que ya encontre la respuesta !

Gracias y hasta luego !