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diff --git a/notes_on_iron b/notes_on_iron new file mode 100644 index 0000000..7facbcf --- /dev/null +++ b/notes_on_iron @@ -0,0 +1,68 @@ +Notes on iron and steel +======================= + +Alloying iron with carbon is of huge importance, but in some processes +the alloying is an implicit side effect rather than the product of +explicit mixing, so it is a complex area. In the real world, there is +a huge variety of kinds of iron and steel, differing in the proportion +of carbon included and in other elements added to the mix. + +The Minetest default mod doesn't distinguish between types of iron and +steel at all. This mod introduces multiple types in order to get a bit +of complexity and flavour. + +Leaving aside explicit addition of other elements, the iron/carbon +spectrum is here represented by three substances: wrought iron, +carbon steel, and cast iron. Wrought iron has low carbon content +(less than 0.25%), resists shattering, and is easily welded, but is +relatively soft and susceptible to rusting. It was used for rails, +gates, chains, wire, pipes, fasteners, and other purposes. Cast iron +has high carbon content (2.1% to 4%), is especially hard, and resists +corrosion, but is relatively brittle, and difficult to work. It was used +to build large structures such as bridges, and for cannons, cookware, +and engine cylinders. Carbon steel has medium carbon content (0.25% +to 2.1%), and intermediate properties: moderately hard and also tough, +somewhat resistant to corrosion. It is now used for most of the purposes +previously satisfied by wrought iron and many of those of cast iron, +but has historically been especially important for its use in swords, +armour, skyscrapers, large bridges, and machines. + +Historically, the first form of iron to be refined was wrought iron, +produced from ore by a low-temperature furnace process in which the +ore/iron remains solid and impurities (slag) are progressively removed. +Cast iron, by contrast, was produced somewhat later by a high-temperature +process in a blast furnace, in which the metal is melted, and carbon is +unavoidably incorporated from the furnace's fuel. (In fact, it's done +in two stages, first producing pig iron from ore, and then remelting the +pig iron to cast as cast iron.) Carbon steel requires a more advanced +process, in which molten pig iron is processed to remove the carbon, +and then a controlled amount of carbon is explicitly mixed back in. +Other processes are possible to refine iron ore and to adjust its +carbon content. + +Unfortunately, Minetest doesn't let us readily distinguish between +low-temperature and high-temperature processes: in the default game, the +same furnace is used both to cook food (low temperature) and to cast metal +ingots (varying high temperatures). So we can't sensibly have wrought +iron and cast iron produced by different types of furnace. Nor can +furnace recipes discriminate by which kind of fuel is used (and thus +by the availability of carbon). The alloy furnace allows for explicit +alloying, which appropriately represents how carbon steel is made, but +is not sensible for the other two, and is a relatively advanced process. +About the only option to make a second iron-processing furnace process +readily available is to cook multiple times; happily, this bears a slight +resemblance to the real process with pig iron as an intermediate product. + +The default mod's refined iron, which it calls "steel", is identified +with this mod's wrought iron. Cooking an iron lump (representing ore) +initially produces wrought iron; the cooking process here represents a +low-temperature bloomery process. Cooking wrought iron then produces +cast iron; this time the cooking process represents a blast furnace. +Alloy cooking wrought iron with coal dust (carbon) produces carbon steel; +this represents the explicit mixing stage of carbon steel production. +Additionally, alloy cooking carbon steel with coal dust produces cast +iron, which is logical but not very useful. Furthermore, to make it +possible to turn any of the forms of iron into any other, cooking carbon +steel or cast iron produces wrought iron, in an abbreviated form of the +bloomery process. As usual for metals, the same cooking and alloying +processes can be performed in parallel forms on ingots or dust. |