Letter 12497 What is Mild Steel?    My son has been asked to find out about Mild Steel as a School Project. Could someone let me have a Description of Mild Steel, How it is Made, Its uses, and the different products made out of Mild Steel Many Thanks, David Blaylock - Braintree, Essex, UK. First of two simultaneous responses --   Hello David! In the States, "mild steel" refers to low carbon steel; typically the AISI grades 1005 through 1025, which are usually used for structural applications. With too little carbon content to through harden, it is weldable, which expands the possible applications. Yet according to my Materials Handbook [link is to product info at Amazon] by Brady, "ingot iron", a grade of nearly chemically pure iron used for construction and magnetic purposes, is also called "mild steel" in the UK. Hope this helps! Lee Gearhart metallurgist East Aurora, NY   Second of two simultaneous responses --   David, You'd get a better answer if you approached one of the faculty at a local University! Mild steel = steel = iron ... where iron ore is heated up along with a goodly measure of coke along with, I believe some gypsum or lime to a eutectic melting point of 1050 degr. C ... eutectic meaning that if the right amount of concentrated iron ore is mixed with these ingredients, then the min. melting temperature in the blast furnace will be as above, ie. less BTU losses.

The resultant mix is iron ore or 'cast iron' but it is quite brittle. Ah, now to make it into steel, we have to reduce the phosphorus and sulphur content AND the carbon content... this is done by adding certain ingredients such as, I believe, aluminum to make the 'iron' more malleable somewhat, ie. to make it into steel. This is done normally in separate furnaces, often called open hearth furnaces, too.

In some steel foundries (mainly abroad)they use a very high phosphorous iron ore. And it was a Englishman by the name of Henry BESSEMER who in effect invented the Bessemer furnace, a large, snorting and spark generating cupola type furnace where the phosphorus generated much of the heat due to a so-called exothermic reaction. Again, this 'iron' has to be treated to make it more workable and not brittle.

Now after this is done ... voila, we have MILD STEEL !

For more boring info, go thou to any steel manufacturer!

I forgot! Usages! Every railway line is made of mild steel, your car or motor bike is made of mild steel, even some of your pots and pans are. The usages are legion! Ships, metal piping, bicycles, you name it!

I hope this helps the school project!

Freeman Newton - White Rock, B.C. Canada

 

Mild steel is a carbon steel typically with a maximum of 0.25% Carbon and 0.4%-0.7% manganese, 0.1%-0.5% Silicon and some + traces of other elements such as phosphorous,it may also contain lead (free cutting mild steel) or sulphur (again free cutting steel called re-sulphurised mild steel) The stuff is used everywhere, looking out of my office window I can see diesel pump injector parts, loudspeaker pole pieces, Automated packing machinery parts and I haven't even got my glasses on. How its made and more info, depending upon the age of your son it's probably an idea he spends a Saturday morning at the local library researching his homework. Whilst the internet's good you still can't beat browsing through books at the library for homework.

Regards,

Richard Guise
- Lowestoft, U.K.

How wrong of Freeman Newton to state that "every railway line" is made of 'mild' steel. All 'curved' lines are made of Manganese Steel, mild steel would just not cope with side thrust of steering a train round a bend!

John P
- Leics, UK.

Thanks for the correction, John, but if you wish to be welcome here, please take care to avoid ad hominems like "How wrong of . . .". I thought Freeman did a nice job of offering the student some examples of products made of mild steel. Some of the components of the other examples he offered like cars, motorbikes, ships, piping, and bicycles are also alloy steel rather than mild steel. Thanks. Ted Mooney finishing.com Brick, New Jersey

Composition: Iron alloy with 0.3% carbon Properties: Malleable and ductile, and therefore bends fairly easily Uses: nuts, bolts, screws, tubes, girders

Methods of Identification:
Appearance: Bright drawn mild steel has a smooth, bright surface; black mild steel is covered with a blue-grey oxide
Dropping: Gives out a ringing note Grinding: Gives off a shower of long white sparks Effect of Heating: Slightly tougher but little change


Mild steel is the most common form of steel as its price is relatively low while it provides material properties that are acceptable for many applications. Mild steel has a low carbon content (up to 0.3%) and is therefore neither extremely brittle nor ductile. It becomes malleable when heated, and so can be forged. It is also often used where large amounts of steel need to be formed, for example as structural steel.

Dominic C. Richards
- Minehead, Somerset, England

The simplest way of describing mild steel is a steel in everyday use which will rust (ie. it is not stainless steel). Many people have made reference to the carbon content of mild steel and unless you know what this does then its pointless. Basically when manufacturing steel carbon is added in varying amounts to alter the properties of the steel.

A low carbon steel such as mild steel will be quite soft and malleable so can be bent and forged into different shapes with minimal heat treatment. Higher carbon steels (up to about 0.9%) can be hardened using a method of heating and quenching (fast cooling in oil or brine) to a point where they can be used for cutting other steels, you would know high carbon steel as a drill bit or lathe tool.

Hope this is helpful.

Scott Bartholomew
- Belfast, Northern Ireland

Hi, Scott. Thanks for the input, but I don't fully agree with it. Mild steel is low carbon steel, steel that is not hard and brittle, the stuff that plates and structural shapes are usually made of. A file will rust very quickly, but I would not consider a file to be made of mild steel -- but maybe when you said "everyday use" you were implying structural shapes as opposed to files.

Regards,

Ted Mooney finishing.com Brick, New Jersey

G,day
I am after some information regarding Mild Steel.
I need to find out the difference between
Mild Steel - Grade 250 and
Mild Steel - Grade 350

The business has previously used the 250 Grade - 32 mm thick, as a Low Temp Molten Lead Bath. Can I use the 350 Grade as I cannot get the 250 anymore in large enough plate section.

Does it have any inclusions the 250 Grade does not have which will shorten its lifespan? Or react with the molten lead?

Greg Cox
Engineer - Newcastle, NSW, Australia

I am doing a school research about those two steels. need to compare their properties and range of uses.. but hard to find relevant information..
can anyone help? or show me some useful website.
thanks..

Todd N [name deleted for privacy by editor]
student - Sydney NSW Australia

Hi, folks. The Internet is a giant one-room schoolhouse, and unfortunately we have questions from engineers and elementary students homogenized into this one thread :-)

Greg might best be served with a reference to the ASM Metals Handbook, but that 20-volume (or so) set might leave Todd with no starting point at all :-)

Todd, I think what you might consider is that steel can be relatively soft (even though a soft steel is harder than a hard wood or hard plastic) or steel can be extremely hard and brittle, or anywhere in between. What hardness you want depends on the application.

Consider a file. If it was softer than the metal you are filing, you'd just wear the teeth off and nothing more. A drill that is not harder than what you are drilling would just spin around until the point was gone. A soft hacksaw would be of no value either. But if you made buildings and bridges and cars of really hard steel, you wouldn't be able to file, drill, or cut them. Further, if you do much metalwork, you'll find that files and drills can break because they are very brittle. You wouldn't want to an apartment building where the I-beams were hardened steel and someone pounding on the ceiling with a broom handle because of a noisy upstairs neighbor would be at risk of shattering the beam and bringing the building down :-) Regards, Ted Mooney finishing.com Brick, New Jersey December 2, 2008 Thanks to all for your Inputs in enhancing my knowledge... Can anybody please suggest the meaning of Mild Carbon Steel... In fact we have received a query from U.K indicating us to use Mild Carbon Steel.. Kindly comment as I don't see anything like Mild Carbon Steel on the entire Google.... Anurag Ranotra manager - NOIDA, U.P, India March 6, 2009 Mild Carbon Steel, is a steel which contains iron plus small quantities of other elements i.e. 0.18-0.23%Carbon, 0.30-0.60%Manganese. 0.30%max.Silicon, 0.040%max. Phosphorous and 0.50%max.Sulfur. Usually steel plates in tanks and structural steel in buildings and other steel structures like billboards and frames of column for electrical cables are made of mild carbon Steel. Remus Serdena welding inspector - Dubai, U.A.E  opt  April 15, 2009 Hello David I'm here to solve your problem. Mild steel is low carbon steel with a variety of applications. The major disadvantage is the poor resistance to corrosion. abdul malik - peshawar, pakistan May 22, 2009 Mild steel is the most common form of steel. Mild steel means - steel with less than 0.15% carbon low-carbon steel, soft-cast steel. Neither brittle nor ductile. This form is use in many applications due to low price material. Shah Khan Soul Feed Chamber - Karachi, Pakistan