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[Envite]

By means of its creation recipe, it seems that Dwarf Fortress steel is not tempered.

Would it be interesting to add tempered steel? It should not be beyond dwarves technological level (Conan was able to do it ), and should include water or, better, water with ice. Maybe a specific steel blacksmith building would be needed, including some barrel for the water in the building materials?

Will try to mod it, but I wish some thoughts before. Each pair of dwarven eyes looking at it will help.

[Urist Da Vinci]

IIRC Dwarf steel currently has the properties of a 400 series martensitic stainless steel (annealed state)(430 MPa yield, 720 MPa ultimate tensile). This could be heat treated to higher strength, at the cost of making the steel more brittle.

[Envite]

The idea would be to pass it from the annealed state to the tempered one.

[Ancalagon_TB]

Hello

Tempering does *not* make steel harder and more brittle, it's the reverse!  Here is how it works:

Step 1:  Quenching (a form of harderning):  The steel object is heated to a high level, then cooled very quickly by dipping in a liquid (water, oil, depends on what you are doing exactly).   This has the effect of making the steel very hard, but also brittle.

Step 2:  Tempering.  After step one, the item is heated again, but *not that hot* - it could be done in a household stove.  This slightly reverses the process, but overall it's a gain - you lose a bit of hardness, but lose a lot of the brittleness.   A proper sword will be quench-hardened, then tempered.

Speaking of steel and sword, I'm not familiar with the properties of all the 400 series steel.  However, I *can* tell you that "ordinary" stainless steel (420) is *not* good sword-making steel.  It's too brittle!  (it's great for knives though).   A sword needs to be able to flex a bit.  Spring steel is far better  - in fact, swordsmiths of modern era with limited means have been know to make pretty good swords using pieces of a car's leaf spring. 

I will note that I'm not a smith, but I was friends with one (unfortunately, he passed away recently) and I picked up a few things

[Envite]

Annealing: http://en.wikipedia.org/wiki/Annealing_(metallurgy) -> Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.

Tempering: http://en.wikipedia.org/wiki/Tempering_(metallurgy) -> Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness

Hardening: http://en.wikipedia.org/wiki/Hardening_(metallurgy) -> Hardening is a metallurgical and metalworking process used to increase the hardness of a metal. // Martensitic transformation, more commonly known as quenching and tempering, is a hardening mechanism specific for steel. The steel must be heated to a temperature where the iron phase changes from ferrite into austenite, i.e. changes crystal structure from BCC (body centered cubic) to FCC (face centered cubic). In austenitic form, steel can dissolve a lot more carbon. Once the carbon has been dissolved, the material is then quenched. It is important to quench with a high cooling rate

Quenching: http://en.wikipedia.org/wiki/Quenching -> In metallurgy, it is most commonly used to harden steel by introducing martensite, in which case the steel must be rapidly cooled through its eutectoid point, the temperature at which austenite becomes unstable.

(Since I'm not english-native, I may have missed some terms or details)

[Urist Da Vinci]

...

Speaking of steel and sword, I'm not familiar with the properties of all the 400 series steel.  However, I *can* tell you that "ordinary" stainless steel (420) is *not* good sword-making steel.  It's too brittle!  (it's great for knives though).   A sword needs to be able to flex a bit.  Spring steel is far better  - in fact, swordsmiths of modern era with limited means have been know to make pretty good swords using pieces of a car's leaf spring. 
...

Agreed.

There are so many types of iron and steel, and methods of making it, some of them lost, that it's not clear-cut for me what the values should be and how many types of iron/steel I should end up putting in and what the materials used should be.

Given that the game only uses the material properties in a partially realistic manner, better questions would be "what value does it add to have another weapon/armor material" or "how good should it be relative to other materials"?

One might interpret weapon/armor quality (-+* etc.) as incorporating the smith's skill at quenching/tempering that specific item (as Q&T is done to finished forged items, not to the raw material).

[Grimlocke]

Hello

Tempering does *not* make steel harder and more brittle, it's the reverse!  Here is how it works:

Step 1:  Quenching (a form of harderning):  The steel object is heated to a high level, then cooled very quickly by dipping in a liquid (water, oil, depends on what you are doing exactly).   This has the effect of making the steel very hard, but also brittle.

Step 2:  Tempering.  After step one, the item is heated again, but *not that hot* - it could be done in a household stove.  This slightly reverses the process, but overall it's a gain - you lose a bit of hardness, but lose a lot of the brittleness.   A proper sword will be quench-hardened, then tempered.

Speaking of steel and sword, I'm not familiar with the properties of all the 400 series steel.  However, I *can* tell you that "ordinary" stainless steel (420) is *not* good sword-making steel.  It's too brittle!  (it's great for knives though).   A sword needs to be able to flex a bit.  Spring steel is far better  - in fact, swordsmiths of modern era with limited means have been know to make pretty good swords using pieces of a car's leaf spring. 

I will note that I'm not a smith, but I was friends with one (unfortunately, he passed away recently) and I picked up a few things

Stainless steel is garbage for weapons and armor, not great for knives either because it doesn't hold an edge very well. It's used for cutlery because it doesn't do the nasty rusting thing and because obviously don't do much heavy duty work.

Dwarf technology level steel would be similar to late medieval blast furnace steel (the reaction implies a blast furnace, and Toady mentioned keeping the tech level <15th century), meaning a non-homogeneous, steel with various possible heat treatments, a somewhat streaked pattern under a microscope and various slag inclusions, mostly silicates, depending on the quality and origin.

The smith's skill was mostly keeping the steel as uniform as possible and getting the heat treatment just right. Making a piece of armor and not heat treating it would actually be fairly daft and imply the skill doesn't know what he's doing, so I always assume that's where the quality levels come in. Various techniques were used, some used water-quenching and then tempered, others used oil quenching and more have been lost in the mist of time. All heat treatment is done after the forging though. It would be really silly to heat treat a bar of steel and then just heat it back up and forge it.

So yeah, trying to put numbers to end result of a medieval armorer is like trying to say how sweet apples are. Surviving specimens are also incredably rare (most are actually early renascence) and curators are not too giddy about them being put through stress tests. Though if someone knows of at least an approximation, if only from a reproduction piece, I would sure like to see it!

Though I wouldn't worry about it too much. To my knowledge adding a reaction to switch around an item's materials required DF hack, and as Urist Da Vinci said putting realistic numbers in DF doesn't guarantee realistic behaviours anyway.

[Loud Whispers]

RIP Damascus steel, best steel of my lyfe o7

[mnjiman]

Gotta temper the steel, and put lots and lots of little crystallized cracks in it! It becomes hard due to the internal structure changing to that of lots and lots of crystals all hugging each other, making it hard! However do to the fact that you know have all these little cracks in the steel, its brittle due to having difficulty holding itself together. Poor steel

However, heating the steel allows for all those cracks to come together and hug each other! You lose hardest due to some of the crystal structure losing its shape, however since the fractures are now healed its loses a lot of its brittleness!

I am of course no smith, or engineer, or anything. Just random thoughts!

[Ancalagon_TB]

Gotta temper the steel, and put lots and lots of little crystallized cracks in it! It becomes hard due to the internal structure changing to that of lots and lots of crystals all hugging each other, making it hard! However do to the fact that you know have all these little cracks in the steel, its brittle due to having difficulty holding itself together. Poor steel

However, heating the steel allows for all those cracks to come together and hug each other! You lose hardest due to some of the crystal structure losing its shape, however since the fractures are now healed its loses a lot of its brittleness!

I am of course no smith, or engineer, or anything. Just random thoughts!

You are essentially right, but your terminology is wrong - step 2 is called tempering.  People confuse quench-hardening and tempering all the time

[mndfreeze]

to the original OP's question of would it be interesting:

I think no.  I dont really see a point in adding a slight variation of steel in.  I think it would be better, if the plan was to find more metals to add to the game, to go the fantasy route and add something like mithril.  Since currently there is only adamantine. 

But really I dont see a purpose to adding yet another ore/metal.  Already so many of the ores/metals in game are mostly useless other then someone who may want their furniture a certain color.  Basically no one CHOOSES to use anything less then steel if they can make steel.  All the lesser metals are only used in the period before you are capable of steel with a new fortress, or you embarked on a spot that just lacks a core ingredient like flux, or Iron I suppose.

I think more specific uses for the metals we have already need to be come up with and added before any more new materials get added in.  Mahaps if some of the other alloys/ores had the same sort of value to the player as steel does... 

[Ancalagon_TB]

I do have to agree that refining iron into steel is more than good enough - add to that the quality level of objects and it's plenty of details.

[Urist Da Vinci]

...
  I think it would be better, if the plan was to find more metals to add to the game, to go the fantasy route and add something like mithril.  Since currently there is only adamantine. 
...

FYI Adamantine is a lawyer-friendly version of Mithril. Toady One didn't want to challenge the Tolkien estate.

[Magistrum]

RIP Damascus steel, best steel of my lyfe o7

Ah, that was just cheating! :P

[Envite]

to the original OP's question of would it be interesting:

I think no.  I dont really see a point in adding a slight variation of steel in.  I think it would be better, if the plan was to find more metals to add to the game, to go the fantasy route and add something like mithril.  Since currently there is only adamantine. 

But really I dont see a purpose to adding yet another ore/metal.  Already so many of the ores/metals in game are mostly useless other then someone who may want their furniture a certain color.  Basically no one CHOOSES to use anything less then steel if they can make steel.  All the lesser metals are only used in the period before you are capable of steel with a new fortress, or you embarked on a spot that just lacks a core ingredient like flux, or Iron I suppose.

I think more specific uses for the metals we have already need to be come up with and added before any more new materials get added in.  Mahaps if some of the other alloys/ores had the same sort of value to the player as steel does...

My idea was to add not only a new metal (tempered steel) but also a new building (let's call it quenching blacksmith). Tempered steel would have better stats for making edge weapons, and same colour.

But it is true that there is an issue of tempering/quenching being applied to the finished item, not to the material. Thus, the reaction should be similar to that of glazing.

Anyway, it seems the consensus goes towards "no, it is not interesting".

You are essentially right, but your terminology is wrong - step 2 is called tempering.  People confuse quench-hardening and tempering all the time

Could you please elaborate in simple words? as I said, I'm no english native, and a simple explanation would be wonderful.