carbon content of steel in manufacture

[picclock]

Not sure if this should be in casting section but its really a question to satisfy my curiosity rather than something with a practical application. Does anyone know how the correct carbon content is achieved during steel manufacture ?  I have this mad thought in my brain that the carbon is burnt out of it and then a specific amount of carbon added - I mean how does that work - A large sack of ground up carbon and a big ladle for stirring it in :-) - but seriously how is the correct and even distribution of the carbon % achieved in the molten mix ?  and what methods are used to measure it ?, some sort of optical spectrum analysis ?

Many thanks for your help in satisfying an overcurious mind.

Best Regards

picclock

(and I have absolutely no intention of going into steel manufacture :-) )

[hermetic]

That is indeed what happens, the molten iron is taken straight from the blast furnace, and then is reacted with oxygen to burn out all the carbon and other impurities, carbon is then added to the required amount, along with many other additives such as manganese,molybdenum, chromium etc to produce the required type of steel. There is an excellent description in the early chapters of "Hardening,Tempering and Heat Treatment" by Tubal Cain (Thomas D Walshaw, ISBN 978-085242-837-5 SI model Books) What I have just told you however is a very simple description of a very complex process! Metallurgy is not for the faint hearted!

[lordedmond]

look up the Bessemer process

having works at a blast furnace complex ( 6 base exchange units ) the thing they do with liquid iron is amazing stir in some magnesium and you get ductile iron, as a treat when I was an apprentice they took us down to Corby to have a loo at the steel production and rolling mills

to see a Bessemer on full chat is a sight to behold 50 foot plume of flame and sparks at some point its orange as the phoserous burns off the operators in those days did it by the colour of the plume when they were satisfied then it was tilted down and a large quantity of carbon and other elements were added up to the blowing position and a brief blast of oxygen ( 8 inch pipe ) to mix it up and then it was poured out into bottom feeding ladles ( 75 - 100 tons ) and the ingots cast .

the thing that has stuck in my mind was the walking draglines we were taken by bus to the outcrop those things looked huge after we had traveled about five miles nearer to them then we new what huge was 

Stuart