# What does the D stand for in the steel grade 16MND5

I would like to know what does the "D" means in steel grade 16MND5.

According to the standard EN 10027:

16 means 0.16 % C MN 5 means 1.25 % Mn (5 must be divided by 4 to get the Mn mass fraction)

But nothing is specified for D.

• I think it follows the French AFNOR standard, not EN according to p30 here publikationen.bibliothek.kit.edu/270046849/3813880 . – user1318499 Jan 22 '19 at 13:45
• The "Internationaler Stahlvergleich" suggests that D is used in Chinese/Russian steel names. For example, 16MnDR is equivalent to Material No. 1.0570. The closest ISO code I could find to 16MnD5 was 16MnCr5 (material no. 1.7131). – Biswajit Banerjee Jan 22 '19 at 22:14
• ccsteels.com/Structural_steel/2305.html is a datasheet from a chinese company. could D mean Mo? – mart Jul 1 at 20:38

This (Table 1, page 4) gives the composition of 16MND5-A508 as

> C     S     P     Mn   Si   Ni  Cr   Mo   V Cu Co Al N
> 0.159 0.008 0.005 1.37 0.24 0.7 0.17 0.5  <0.1
> Weight % - iron balance.


A508 is the relevant ASTM standards document (not a free publication.)

• It is not ASTM A508 unless is is marked and certified as A508. – blacksmith37 Oct 19 '19 at 21:35

Having looked at the link,

D is for Flat products for cold forming, and is usually followed by two numbers characterising steel

Based on the diagram in the same link:

• You refer to naming according to category 1 (Steel specified by purpose of use and mechanical properties). The steel grade 16MND5 belongs to category 2 (Steel specified by chemical composition). The scheme en.wikipedia.org/wiki/File:EN10027-steelgrade-diagram.svg gives more details about the naming specification. According to this scheme, D should be alloy element. But I don't know of any element with element symbol D. – Stellarator Jan 22 '19 at 11:27