Opravy

Steel

• I was thinking what I should write about, and nothing came to my mind.

• Just recently I had an exam from Properties of materials, and only thing that is currently in my head is steel, In this short entry I will try to summery what steel is, what are its properties, how it is made, and where it is used.

• But first, what is alloy ?

• Alloy is a mixture of 2 or more different chemical elements from whitch at least one is metal ( other elements can, but do not have to be metals ).

• Now you are probably asking yourself why did I mention word alloy ?

• I mentioned word alloy, because steel is an alloy.

• Main element in steel is Iron(Fe), and main additive element is carbon(C).

• Steel without carbon is not steel.Of course steel in its microstructure has other elements except iron and carbon.

• Some of them positivly effect properties of steel, those are Crom(Cr), Tungsten(Tg), Copper(Co), Manganese(Mg), Titanium(Ti) (usually other metals), while some of them negativly effect properties of steel like Sulfur(S).

• Percentage of carbon in steel ranges from 0-2%, if in a mixture there is more than 2 % carbon, then that metal is used for casting and as such is called cast( "cast" is directly translated from Croatian word "ljev", I do not know english word).

• Properties of steel mainly deppend on how much carbon it has in it’s microstructure.

• More carbon steel has, harder it becomes, but it becomes more brittle as well.

• Less carbon it has, well, more like iron it is( you can think of it as mixing properties of iron and diamond (as diamond is allotrpic modification of carbon)).

• Sadly steel is corrosive but that can be fixed by adding arround 1% Copper, or 12+% Crom.

• One of best propperties of steel is it strength, It can support a lot of force without breaking.

• Even cooler is that steel can be intentionally put through time-temperature processes which can increase some of its properties.

• Process of making steel is like baking cookies, mix ingredients, put in oven, het au, and voala. only difference is that your ingredients are not fllower and egs, but iron and graphite, your oven is not quite up to the job of "baking" steel as steel melts at arround 1500°C so you need quite specialised furnaces to do the job.

• There are several types of furnaces, and deppending on the eype of furnace, ammount of impurities (S) changes, but I will not go any deeper than this as even this is quite long, and it was supposed to be short :D.

• And i can bet that in your life you have at least once held object made of steel, without even knowing it is made of steel.

• In penciles you have those springs, Springs are made of "steel for springs" :D.