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What exactly is Mild Steel?

Q. 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

A. 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 [affil link on 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
Lee Gearhart
metallurgist - E. Aurora, New York


A. 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 °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, i.e., 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, i.e., 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 ... voilà, 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 portrait
Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

A. 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 [last name deleted for privacy by Editor]
- Leics, UK.


Thanks for the correction, John, but please try to avoid ad hominems like "How wrong of . . .". Freeman did a nice job of offering the student some examples, and actually 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 again for the enlightenment about curved rails though!

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

April 4, 2011

Actually I think the thing John P. (Leics) could have made more of from Freeman's little blurb is the use of voilà anywhere in an article about steel...

Surely it is the creeping end of one or the other of the languages in use...

It's getting in everywhere - Macdonald's & Nescafe's advertisements if you please chuck in - and voilà


Bruce Trout
- Cookham, Berkshire

April 4, 2011

thumbs up sign Hi, Bruce. Focus please! Voilàs & violins are made of wood, not steel.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Hey Ted, Viola=stringed instrument. Voila=there it is, which has nothing to do with a wood stringed instrument.)

Mike Gee
- Sayville, New York, USA
September 27, 2015

thumbs up signGee, Mike, I actually knew that.
But thanks!


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
September 2015

A. 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.


Richard Guise
- Lowestoft, U.K.

A. 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

A. The simplest way of describing mild steel is a steel in everyday use which will rust (i.e., 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

April 29, 2008

Hi, Scott. Thanks for the input, but I can't quite 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 and drills and similar tools.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

June 16, 2008

Q. 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

Q. 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.

Todd N [last name deleted for privacy by Editor]
student - Sydney NSW Australia
June 28, 2008

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

Greg might best be served with a reference to the ASM Metals Handbook [affil link], but that 24-volume 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 saw the component parts. Further, if you do much metalwork, you'll find that files can shatter and drills can break because they are very brittle. You wouldn't want to build an apartment building where the I-beams were very hard 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 :-)


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
June 30, 2008

Q. Thanks to all for your Input 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
December 2, 2008

A. 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 
March 6, 2009

A. 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
April 15, 2009

A. 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
- Karachi, Pakistan
May 22, 2009

A. Sadly there doesn't seem to be a good answer as to why Mild steel is called Mild, unless you take the mild to mean malleable or easily worked, which low-carbon steels certainly are. Wrought Iron preceded it and was very fibrous and got its structure from being repeatedly worked when hot.
Confusingly Cast Iron has even more carbon in it, (and even less iron as a result). It isn't easy to work, but is very easy to cast into a wide variety of shapes. The purest iron can often be found in "tin" cans, which actually have very little tin in or on them.

Neil Hartwell
- Fowey, Cornwall, UK
March 27, 2010

Q. Dear Sir
I want to know can we use mild steel in place of ST 37 -2?

Thank you.

Shalander Sharma
- Dharuhera,Rewari,Haryana, India
April 24, 2010

A. Hi, Shalander. Sorry, no, you can't make such a substitution. But please tell us about the components in question and a fuller answer may be possible.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
April 26, 2010

August 12, 2010

As for the comment about mild steel and a rusting file, the reason why the file would rust quickly is because of its high carbon content. A higher carbon content makes the steel oxidize, or rust, quicker. However, mild steel will still rust quickly. Alloy steel such as chromoly are slower to oxidize, but that is mainly due to the addition of chromium and molybdenum, however they will still eventually rust. Even some stainless steels, such as 400 series stainless when compared to 300 series stainless, will eventually rust if left exposed in certain environments long enough, due to the simple fact that 400 series has a higher carbon content than 300 series. However on a side note, 400 series stainless is harder and has greater heat fatigue strength than 300 series stainless, making it ideal for cutlery and catalytic converter shells. Anywho, higher carbon content means less resistance to corrosion, but in general, greater strength and hardness. Mild steel kinda sits in the middle on this one as far as corrosion goes.

Jeff Garner
- Denton, Texas, USA

Q. I read the answers and I have some confusion that Mild Steel or Mild Carbon Steel both are different parts.

Generally we known that their are such type of steels i.e. Mild Steel, Carbon Steel, Stainless steel.

Query: Mild Steel & Mild Carbon Steel main difference in both....

K Mittal
- Delhi, India
December 8, 2010

A. Hi, Mittal.

These terms are vague, context dependent, and just handy slang used to describe something when you don't have more exacting information. They are broad brush terms that you cannot really put a fine point onto, but I would say there is no difference between mild steel and mild carbon steel.

Here is some general stuff:
- Stainless steel or corrosion resisting steel has significant amounts of other metals in it. For example 3xx stainless steel usually has about 18 percent chromium and 8 percent nickel, and sometimes some additional metals like molybdenum. 4xx stainless steels usually have about 18 percent chromium.
- Mild steel usually means a soft, unhardened steel of low carbon content, like 0.2 percent. This is what I-beams and structural elements for buildings are made of.
- Carbon steel usually means steel with "carbon only", in other words a non stainless steel. It may be mild steel, but not necessarily. For example, a spring might be made of stainless steel or of carbon steel, but a spring is not made of mild steel. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
December 8, 2010


January 24, 2011

A. Hi, Amy.

I don't think "corrosivity" is the word you are looking for. I believe that a strong acid would have "corrosivity", whereas a steel which is designed to resist corrosion would have good "corrosion resistance".

There are countless ways to improve corrosion resistance, from applying coatings like paint, galvanizing, and chrome plating, to slightly modifying the composition to make Cor-ten (a steel which builds a more robust rust layer, deterring further corrosion), to major modification of the ingredients like adding nickel and chromium to make the steel corrosion resistant -- but in that case you have "stainless steel" and the term "mild steel" doesn't really apply anymore :-)

Again, an issue with the question is that "mild steel" is simply slang, and its meaning somewhat context-dependent. One of the implications of "mild steel" is that it is not corrosion resistant; so as you change its composition to make it more corrosion resistant, the semantic question immediately arises of whether it is valid to continue to call it mild steel :-)


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
January 25, 2011


tom hinsey
- benld, Illinois U,S.A.
March 18, 2011

A. Yes, Tom, it is.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
March 21, 2011

Q. I want to know if we can increase the hardness of mild steel or not. How?

Nad Hana
- Malaysia
November 2, 2011

A. Hi, Nad. I am not a metallurgist, so my answer is not conclusive, but I have never heard of it and think it's not possible because it has insufficient carbon to be hardened through heat treatment. Of course there are surface treatments that you can do to impart a hard surface. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
November , 2011

Q. Here's a related question that has surfaced in my efforts to find the best wood stove for home heating. I have heard that some WOODBURNING STOVES are made of BOILERPLATE STEEL, while others are of MILD STEEL, the implication is that boilerplate is better somehow. Bearing in mind that the stoves in question are not boilers, but radiant space heaters. What would be the advantage in using boilerplate instead of an appropriate grade and thickness of mild steel? Note: most of these stoves have a firebrick lining. And is there an "ideal" alloy for wood stoves, or is cast iron the time tested champ? Thank you.

Robert R West
- Saugerties, New York, USA
January 10, 2012

I need some help about melting and pouring mild steel. So please, I need answers to some questions. What is the process of melting mild steel? What type of scrap may be used to melt it? How long it's pouring duration?

Khagendra Dahal
- Biratnagar, Morang, Nepal
March 9, 2012

June 13, 2012

Q. Hi!

After reading this particularly interesting thread, I have a question of my own that I would love all of your thoughts and opinions on.

My company specialises in recycling car tyres. Out of the tyres we remove steel wire. This is potentially a very good product, but many buyers could use more if it included a lower phosphorous content.

Is there any method to reduce the phosphorous content?

Tyre wire scrap is a malleable steel, characterized by High Tensile Carbon Steel (Carbon content: 0,82%). Steelcord scrap is shaped in chopped wire form (wire diameter: 0,20 - 0,80 mm) and is obtained during the granulation process of waste tyres. The partial textile fibers and the steel filaments are separated mechanically from the rubber matter and are addressed to a magnetic device for its separation and collection

Steelcord Scrap can be classified as ISRI CODE: 281 Processed tire wire (Ferrous)Grade 4. (rubber/fiber contamination < 20% detected by manual separation)


Oliver Chapman
- Cheshire, UK

November 8, 2012

A. David,

I encourage you and mostly your son to do some research by himself, because some of the information on the top as I see are false, that's why I decided to post this for you.

Hopefully it helps ...

Mild steel (low carbon steel)

1. The commonly used alloy for structural steel members

2. Not more than 0.3% carbon

3. Small amounts of other alloys (such as nickel, chromium, molybdenum, manganese, vanadium, and silicon) improve strength, toughness, and other qualities

4. Reasonably strong, highly ductile, and easily welded

5. Equally strong in tension and compression

Erfan Mehdibeik
- Seattle, Washington, U.S

November 12, 2012

A. Hi Erfan.

Thanks for the informative answer. However, if you feel that "some of the information on the top as I see are false", it would be best to challenge the specific statements that you question rather than to use a brush so broad as to call into question every contribution from a dozen responders over a period of many years :-)

Thanks again.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey


- Johor Bary, Johor, Malaysia
July 31, 2013

A. Hi Azman. No, it can't; the carbon level is too low for hardening. But "mild" is not a detailed specification, so the question and answer are not as exacting as they could be.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
July 2013

Q. Can anyone tell me what is the grade of mild steel which is used to make bike frames such as rear, front, bottom and swing arm?

Vipin Malhotra
August 5, 2014

A. Hi Vipin. Questions are usually answered better when you explain your situation and tell the readers why you want to know. Bicycles can be built from plain minimum quality mild steel such as ASTM A36 [affil link] (36,000 psi yield point), but most consumers, even cheap ones, are concerned with the weight of a bicycle, so stronger low-alloy high-tensile steels like are common even on moderately priced bicycles, and very high tensile strength steels are sometimes used on custom bicycles.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
July 2014

August 5, 2014

Q. Sir
I want to know that what is the grade of mild steel which is used to make bike frames of Honda Shine such as rear, front, bottom and swing arm? Sir I am collecting this information because I have to give an interview in Honda's vendor company in a quality department. They ask this question mostly; I searched on the net but I found nothing.

Vipin Malhotra [returning]

A. Well, no harm in asking, but I think the only answers you will get will involve the word "probably" and speak only of the "general types" of alloys "often used" for such purposes. Nearly every manufacturing detail at every manufacturer is considered proprietary. Unless there is some sales advantage for Honda in telling consumers what kind of steel they use, it's probably proprietary knowledge.

You are speaking of a motorcycle, rather than a bicycle, so economy may trump strength-to-weight ratio, and I would guess that they are built of cold finished drawn-over-mandrel tubing. Best of luck with the interview.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
August 2014

Q. I want to know that what are the disadvantages of mild steel? And what are the chemical and mechanical composition acurate?

Student - Ghaziabad, U.P., INDIA
May 22, 2015

Hi Sachin. Disadvantages compared to what alternative and for what application? Compared to medium or high carbon steel or alloy steel, it's weak. And compared to stainless steel and most other metals, mild steel corrodes fairly readily.

As for the accurate chemical composition and mechanical properties, you need to specify a particular grade, because "mild steel" is a term with fuzzy borders. It's like asking exactly how tall and many how pounds a medium-height pleasantly plump person is. In a steel book, find a grade that contains .15 to .2% Carbon, verify that the grade is considered a mild steel, and copy the chemical composition and mechanical properties from there. Good luck!


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
July 2015

Q. I am considering different engine guards for a motorcycle. During my research I have found one brand which states "Mild Steel" and another that indicates it is "Heavy Steel". What is the difference between the two? Is Heavy steel more resistant to rust? Thank you.

steve wilson
- johnson city, Tennessee, usa
July 12, 2015

A. Hi Steve. "Heavy" steel is pretty much meaningless. It just means thick in gauge as opposed to thin in gauge -- but compared to what? Steel is not resistant to rust; the paint or powder coating and its pretreatment system is what deters rust. Good luck.

On my last trip through Johnson City (and I mean final, not most recent) I got a robo ticket mailed to me from Las Vegas; you're not very welcoming down there :-)


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
July 2015

Q. Can I use Mild steel instead of cast Iron to build Machine body? If not why?

- Dhaka. Bangladesh
September 17, 2015

A. Hi Noor. I don't see any reason you can't do so if you find that the advantages of steel outweigh the disadvantages. I think it's just that when machine body members are very heavy and loaded in compression, just casting them with the necessary fillets, holes, radii, etc., ends up being more practical than fabricating, welding, and stress relieving steel.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
September 2015

thumbs up signHi Mr Noor,

It's so refreshing to see someone want to make a better product.
I'm seeing the automotive world moving the other way to save substantial costs.

4Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind
supporting advertiser
Bengaluru, India
Saify logo
October 9, 2015

Mild steel is an alloy used on metal burgers.

alfie foxall
- Birmingham, Midlands,England
September 30, 2015

September 2015

Probably true, but in which aisle can we find that special sauce?


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

Q. I want to cut down the metal corner legs of a loft bed and make it into a daybed ... is that type of metal ferrous or non ferrous please? I am thinking non-ferrous because of the description but I could be wrong. I just don't want to use the wrong saw blade to cut it per safety and to not mess up the legs themselves

Tina Marie
Home Healthcare - Williamston, North Carolina United States
December 29, 2017

A. Hi Tina. Mild steel is the most common construction metal because it's strong and inexpensive, so that's probably what it is. Steel is ferrous and magnetic.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
December 2017

So the answer I need would be non ferrous then?

Tina Marie [returning]
Home Healthcare - Williamston, North Carolina United States
December 29, 2017

December 2017

Hi again. No, the opposite; my guess (based on nothing but probability) is that the bed legs are ferrous.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

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