Writing up metallurgy for a campaign

[tantric]

Is this realistic fantasy? It would be interesting to create a variety of fantastic material with different properties...

As to the Low Metals, Absium, Viridium, Irisium, Xenobium, Mercurium, Azurium and Cinnibrium, each has certain problems that make them impractical. First is rarity - any of them are worth ten times their weight in diamonds. Absium is actually a gas at room temperature - it is discharged from the High Metals as their magic is consumed. Viridium is a green metal, softer even than Aurium and useless for any kind of physical application. Irisium, though beautiful beyond compare, covered with shifting rainbow auras, is harder to work than Adamantium and is found only in one area of the Burning Desert. Azurium is a royal blue metal which is found only in the deepest Waters and begins to corrode immediately on exposure to air. Cinnibrium, though as workable as Argentium, reacts with blood, corroding rapidly. Mercurium is a silvery liquid metal that is extremely poisonous. There are puddles and lakes of Mercurium throughout the Underworld. Xenobium is found only in the Savant maintained sanctuary of HomeAway, and rapidly decays to Absium outside it's borders. There are rumored to be other Low Metals, though they must be rare beyond hope of collection. These Low Metals will alloy with each other, but not with the HighMetals. Their only real use in certain ArtCrafts (and other Magics), and as Jewelry. Nevertheless, as the air in Worldstree is at least 1% Absium at sealevel, using Magic, one can create any of them from thin air in large quantites.

There is another option in the form of Vitredur, which a form of magically shaped diamond. It is incredibly expensive, but lighter and stronger than Adamantium, though just as difficult to work. For the most part, it is used to make swords, shields and armor plates to be attached to suits of Mithril mail. Vitredur, along with Plastics and Ceramics, are the products of ElfTech.

[aesir23]

For fantasy, I wouldn't worry too much about the minutia of how much DR or HP a bar of different metals has.

What matters is: who does equipment made of this material differ from equipment made of the standard material (especially weapons and armor). This is a much simpler enterprise.

FREX: Treat Bronze as Steel, except CF 5. Mythril weapons never break and weigh 1/2 as much CF 100. Mythril Armor has +4 DR and 1/2 Weight for CF 100, or can be made thicker: +8 DR, full Weight, -1 DX, CF 200. Etc...

Only very rarely will you have to determine how difficult it is for your adamantium axe to cut through the mythril bars of a jail cell. In those situations, just make something up.

[Pursuivant]

As a cheat, you can always use the stats for high tech materials and just call them by different names.

GURPS Low Tech, GURPS Fantasy and some of the Dungeon Fantasy books have material you can mine - so to speak.

[Fnugus]

Long time without me having time to check back in here. Okay, some thoughts.

Originally Posted by Polydamas

What do you mean by “strength”?

See, this is the question I'm trying to figure out myself. How does GURPS define "strength" in relation to DR/inch?

Originally Posted by Polydamas

I think that even trained metallurgists rely heavily on experiments to predict the properties of a new alloy, and the formulas which they have are very complicated and assume a world which does not work the way many fantasy settings do (one without spirits, undead, disintegration rays, or enchantments of unbreakability but with industrial processes which can make identical sheets of metal).

This could be a great excuse to learn some metallurgy, but I don't think you will learn much that is helpful for gaming.

True. However, I'm mostly interested in existing metals and alloys, and then new ones can be extrapolated. Just need to have a few, well-known basics in place first.

Originally Posted by benz72

Many people mistakenly believe that steel has a higher C content than Iron. This is inaccurate.
Compare C content listed here
http://en.wikipedia.org/wiki/Carbon_steel
with
http://en.wikipedia.org/wiki/Cast_iron

The trick isn't getting in more Carbon but rather getting Carbon and Oxygen out to leave purer Fe and THEN carefully controlling the additions of alloying agents.

This is not entirely true. The most commonly used iron alloy was wrought iron, containing less than 0.25 % carbon, whereas steel is less than 2.1 %. Cast iron, with carbon content of 2.1 % and up, were not in common use before the rennaissance (in Europe, at least). Cast Iron is very brittle and hard, whereas steel is quite soft and malleable. Which you can actually also read from the links you posted, if you also look at the sidebar containing references to other iron alloys.

Originally Posted by tantric

Is this realistic fantasy? It would be interesting to create a variety of fantastic material with different properties...

Very difficult question. Yes, and no. Yes in the way that the physical world needs to make sense and be realistic (or at least well grounded). Once that foundation has been laid, magical and other exotic materials and effects will be added.

And yeah, it's very interesting to create a host of fantasy metals. Where does your quote come from?

Originally Posted by Pursuivant

As a cheat, you can always use the stats for high tech materials and just call them by different names.

GURPS Low Tech, GURPS Fantasy and some of the Dungeon Fantasy books have material you can mine - so to speak.

I didn't find anything of particular use in Low Tech. I haven't had the patience to figure which one(s) of the DF books I could potentially use (there's like a million of them). Fantasy actually didn't occur to me, I'll have a look. If you can guide me to which ones of these books (and maybe also chapters/pages), it would be fantastic.

[Polydamas]

Originally Posted by Fnugus

See, this is the question I'm trying to figure out myself. How does GURPS define "strength" in relation to DR/inch?

GURPS does not define "strength" in that context. It defines DR as resistance to penetration by projectiles, and scales it so that RHA steel has DR 70/inch and other materials have strength in proportion. Some people find the proportion by research and others make it up.

[Turhan's Bey Company]

Originally Posted by Fnugus

How does GURPS define "strength" in relation to DR/inch?

The problem--or, at any rate, a problem--is that I suspect that you're after a formula which is far beyond the scope not just of GURPS but of just about anyone who isn't a technical specialist. As I understand it, RHA-equivalent is sort of the yardstick for discussing modern armor, so people who come to GURPS with real-world armor stats expressed in RHAe can come up with an equivalent DR. However, coming up with an RHAe for something is what scientists call Very Difficult, and doing the massive work involved is the realm of materials engineers with government grants. So GURPS authors don't have a method for determining DR beyond:

1) If there's a published RHAe for the material/item, use that.

2) If not (which is probably universally the case for anything historical), make something up that looks good.

At any rate, even if you were to come up with RHAe values for a range of the sorts of alloys one finds historically, the inability of ancient smiths to precisely control their materials and manufacturing conditions puts some significant error bars of the quality of what they make from batch to batch. So you'd end up having to track a list of "Platonic ideal" materials and how close any given smith got to that on any given batch of material while smelting and alloying and the extent to which a later smith, making an item from that batch of metal, changed it. Oh, and without sophisticated testing technology, neither the smith nor his customers will be able to tell the difference with much more granularity than "this is junk," "this is OK," and "this is pretty good."

[Fnugus]

Originally Posted by Polydamas

GURPS does not define "strength" in that context. It defines DR as resistance to penetration by projectiles, and scales it so that RHA steel has DR 70/inch and other materials have strength in proportion. Some people find the proportion by research and others make it up.

Sure. The big question is, in relation to GURPS game balance compared to weapon damage output, how does it scale? Does half the RHA of steel means half the DR?

Originally Posted by Turhan's Bey Company

The problem--or, at any rate, a problem--is that I suspect that you're after a formula which is far beyond the scope not just of GURPS but of just about anyone who isn't a technical specialist.

Haven't someone made a "formula" for damage in relation to "muzzle velocity" or some other measure of power for HT and UT weaponry? In that case, how? And how does it compare to the stats of armors/DR?

Originally Posted by Turhan's Bey Company

As I understand it, RHA-equivalent is sort of the yardstick for discussing modern armor, so people who come to GURPS with real-world armor stats expressed in RHAe can come up with an equivalent DR. However, coming up with an RHAe for something is what scientists call Very Difficult, and doing the massive work involved is the realm of materials engineers with government grants. So GURPS authors don't have a method for determining DR beyond:

1) If there's a published RHAe for the material/item, use that.

2) If not (which is probably universally the case for anything historical), make something up that looks good.

At any rate, even if you were to come up with RHAe values for a range of the sorts of alloys one finds historically, the inability of ancient smiths to precisely control their materials and manufacturing conditions puts some significant error bars of the quality of what they make from batch to batch. So you'd end up having to track a list of "Platonic ideal" materials and how close any given smith got to that on any given batch of material while smelting and alloying and the extent to which a later smith, making an item from that batch of metal, changed it. Oh, and without sophisticated testing technology, neither the smith nor his customers will be able to tell the difference with much more granularity than "this is junk," "this is OK," and "this is pretty good."

Which is all pretty good. The idea is just to get some sort of guideline as to what RHAe means in relation to DR. And for this, only a select few handful of materials are needed stats for. Just three would do, I think, if stats for both DR and RHAe could be had. That's enough to extrapolate from. Just finding the relation/ratio/scale between RHAe and DR in the first place is what I'm after.

[DanHoward]

Low-Tech assumed that a 1mm breastplate of RHA equivalent steel was DR 3 and that every +0.5mm granted an extra +1 DR. Bronze was exactly the same except that it cost more. Hardened steel added a flat +1 DR. The problem is that the DR includes the fact that breastplates have a deflective component that used to be PD in the old GURPS. The DR also incorporates some light underpadding that isn't thick enough to be DR 1 on its own. This seems to work ok at breastplate thicknesses but not at vehicle plate thicknesses. You have to use some variant of Douglas' "Armor as Dice" mechanics for those.

[Polydamas]

Originally Posted by Fnugus

Sure. The big question is, in relation to GURPS game balance compared to weapon damage output, how does it scale? Does half the RHA of steel means half the DR?

As I said, armour equivalent to 1” of RHA has DR 70. Armour equivalent to twice or half that thickness has twice or half the DR. Projectile damage scales roughly with the square root of kinetic energy divided by diameter, and the DR of a flat plate scales roughly with thickness. (It seems that things get more complicated at very high velocities and high energies, but this works well enough for bullets and arrows).