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I am starting to use steel in some of my designs, and while trying to learn more about this material and its properties I have realized that there is so much more to it than I thought.

How does the grading system used for steel work? For instance, what does "Grade 11SMn30" mean, and how does this affect the properties of the material?

Answers/comments indicate there are multiple standards, which I did not know, but I've found out that this is an EN grading.

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Based on it being an EN steel grade:

The first number is 100x the carbon content percentage (so 0.11%), the letters are added elements (sulphur and maganese), and the last number is the sulfur content (0.30%). You can see the full details here.

The full format seems to be:

[X][% carbon][added elements][% of added elements, hyphenated]

Note that the X is only present for stainless steels. Here is a good example.

Note also that this scheme is somewhat ambiguous. The percentages are only an approximation, and the example you gave is interesting because it lists Sulfur before Maganese, despite the naming convention stating that they should be listed in order of content.

That's alright for getting quick basic info about the steel, but for anything else you may want to use the EN number, 1.0715, rather than the name. Wikipedia has details on the format. Given this classification you can find out much more about the steel's properties and see what general category it fits into. The site I linked first says this:

EN 10277-3: 2008 Bright steel products
Technical delivery conditions. Free-cutting steels

EN 10087: 1999 Free cutting steels
Technical delivery conditions for semi-finished products, hot rolled bars and rods

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  • $\begingroup$ Are there any rules of thumb, like higher carbon makes it better in propertyX but worse in propertyY, or addition of S or Mn makes it <whatever> ? I'm realising that this is way more complicated than I first thought, I'm trying to understand how those values affect the properties. $\endgroup$ – jhabbott Jan 21 '15 at 1:15
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    $\begingroup$ @jhabbott I think that might be too broad to cover here. There are so many properties and potential applications, you could have an entire course on it. If you have a specific application in mind, it might make sense to ask a separate question about what kind of steels would suit. $\endgroup$ – Matthew Read Jan 21 '15 at 1:27
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    $\begingroup$ @jhabbott you're basically asking for a primer on material engineering. Each metal has a different set of characteristics, which can generally be found online by searching for that material type, or by asking the foundry that makes the metal. Anything that has an EN, DIN, AISI, or JIS (etc.) number generally needs to be tested on a variety of categories to get that classification. $\endgroup$ – jmac Jan 21 '15 at 3:27
  • $\begingroup$ @jhabbot Additionally, heat treatments play a significant role in steel properties, on top of what composition allows for. chasealloys.co.uk/steel/alloying-elements-in-steel Gives a general idea, but these are rules of thumb, and many factors are important to determining steel properties. $\endgroup$ – wwarriner Feb 8 '15 at 6:15
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The numbers from 1 to 9 indicate the type of steel. The first 1 is for carbon steel, and the second 1 and the S mean that sulfur has been added to it. The Mn stands for "manganese" and 30 is the amount of carbon in the steel, expressed as a fraction of 1%. It really means, .30% carbon.

More information can be found in sources such as this one. The above answer would be responsive assuming that it is an American designation, but a commenter pointed out that it could be an English code, which would mean something different. In any event, it is the responsibility of the questioner to define these things.

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  • $\begingroup$ That's good information so far, I'm also interested in how the gradings affect the properties of the material. $\endgroup$ – jhabbott Jan 21 '15 at 0:55
  • $\begingroup$ You should ask another question about that! $\endgroup$ – Rick supports Monica Jan 21 '15 at 16:12

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