Steel is the first alloy hardly anyone can avoid. According to the game data Steel Sheets are consumed in 160 different structures, and steel ingots appear in many printer recipes on top. The arc furnace cannot make steel – you need the gas furnace.
The recipe
In words:
- 75 % iron and 25 % carbon – carbon is in Charcoal. Alternatively hydrocarbon from Ore (Coal) works at the same ratio.
- Temperature from 900 K (627 °C), open upwards.
- Pressure from 1,000 kPa, open upwards.
The amounts are shares. For 4 steel ingots you need 3 units of iron and 1 unit of carbon, for example 3 iron ore and 1 coal. For 40 steel ingots it is 30 iron and 10 coal.
Ore or ingots?
An Ingot (Iron) holds just as much iron (1) as a piece of Ore (Iron) – but no gas. That makes a big difference:
| Charge for 16 steel | Gas released when melting |
|---|---|
| 12 iron ore + 4 coal | 12 · 2.5 + 4 · 13 = 82 mol |
| 12 iron ore + 4 charcoal | 12 · 2.5 + 4 · 6 = 54 mol |
| 12 iron ingots + 4 charcoal | 4 · 6 = 24 mol |
Less exhaust means the pressure is easier to hold and you have to vent less. You make iron ingots quickly in the Arc Furnace, see The arc furnace: ore to ingots with electricity.
How much gas has to be in the furnace?
The furnace has a 1,000 litre chamber. For 1,000 kPa at 900 K you need:
n = p · V / (R · T) = 1,000 · 1,000 / (8.3144 · 900) ≈ 134 mol of gas
The 82 mol from 12 iron ore and 4 coal only make about 614 kPa at 900 K. Fuel and combustion gases supply the rest. So gas in the furnace is not just waste – without enough of it you will not reach 1,000 kPa.
Step by step
- Build the furnace. The kit Kit (Furnace) comes from the Autolathe (iron 30, copper 10). Then two iron sheets each with wrench and welding torch.
- Connect pipes. One pipe to the gas input for the fuel, one to the gas output for the exhaust. The furnace also has a liquid output.
- Prepare the fuel. According to the combustion table methane burns with oxygen at a ratio of 2 : 1, hydrogen also at 2 : 1. The table below shows all pairs and what they produce.
- Fill it. Keep the mould closed (
Open= 0). Put iron and carbon at a ratio of 3 : 1 into the import slot or feed them in by chute. - Heat it. Let the mix in and ignite it with the ignition button (
Activate) until the furnace is above 900 K. Ore only melts from 373.15 K, coal from 323.15 K. - Hold the pressure. Stay above 1,000 kPa. The basic furnace does not regulate anything itself: at the gas output gas flows out as long as the pipe has less pressure, and back into the furnace if the pipe has more. So you set the pressure through the output pipe, for example with a pump behind it.
Settinghas no effect on the basic furnace. Gas pipes hold 60,795 kPa at most. - Open the mould. Once everything has melted and temperature and pressure are right, set
Opento 1. Now the ingots come out, one per unit of mix.
Pressure rises with temperature. If you fill the cold furnace to 1,000 kPa, you will have about three times that at 900 K. Heat first and set the pressure afterwards.
Watching the furnace with IC10
A light should be on while the furnace is inside the steel window. The chip reads Temperature and Pressure by name and compares them with the limits:
# Show the steel window at the furnace
define FURNACE 1947944864 # Furnace (StructureFurnace)
define LIGHT -1860064656 # Wall Light (StructureWallLight)
define NFURN HASH("Furnace Steel") # name of the furnace
define NLIGHT HASH("Light Steel") # name of the light
define TMIN 900 # K, minimum temperature for steel
define PMIN 1000 # kPa, minimum pressure for steel
define PMAX 50000 # kPa, own safety limit
alias temp r0
alias press r1
alias ok r2
alias tmp r3
start:
yield
lbn temp FURNACE NFURN Temperature 0
bnan temp start # no furnace with this name
lbn press FURNACE NFURN Pressure 0
bnan press start
sge ok temp TMIN # hot enough?
sge tmp press PMIN # enough pressure?
and ok ok tmp
slt tmp press PMAX # still below the safety limit?
and ok ok tmp
sbn LIGHT NLIGHT On ok
j startPMAX is not part of the recipe – steel is open upwards. The limit only warns you before the pipes reach their limit. How lbn and sbn work with names is explained in IC10: control a device by name.
What you make from steel
In the Autolathe steel becomes sheet: 0.5 steel per Steel Sheets, 3 s, 500 J. One ingot gives two sheets. For steel sheets on a large scale a furnace that only makes steel pays off.
Common mistakes
- No steel forms: check the ratio first. Stick to 3 : 1 and count leftovers from earlier batches.
- Pressure too low: with ingots instead of ore the exhaust is missing. Let more fuel mix in.
- Iron ingots instead of steel: the mould was open before the coal had melted. Melt everything first, then open.
- Pressure runs away: no gas outlet, or the output pipe already holds the same pressure. Without a pump behind it nothing drains off any more.
- You wanted solder instead: solder needs 350–550 K. At steel temperature the furnace is far too hot for that.
Further reading
- All alloys and their windows: Furnaces and alloys and Furnaces and alloys
- Work out a furnace charge: Furnace calculator
- Next level: Super alloys in the advanced furnace