What Do We Mean When We Say Alloy Steel?

Thanks Milo, but some will argue you the strength issue just for the sake of arguing.

Alloy steel contains elements such as chromium, nickel,vanadium,molybdenum,tungsten, cobalt,boron,copper apart from higher amounts of manganese, silicon,phosphorus & sulphur.

These additions in variable volume depends up on grade and helps to strengthen the ferrite, corrosion resistance,better harden-ability, grain size control,greater strength,stability to temperature variation,improved ductility etc.

They are divided in 4 groups, such as:

1. with yield strength range of 310 - 480 N/mm²,

2. with yield strength range of 350 - 1240 N/mm²,

3. quenched & tempered to achieve max. strength & hardness,

4. chromium & molybdenum steels to provide service temperatures up to 740⁰ C. these

alloys help to provide high resistance to oxidation at elevated temp. service.

sridhar.

Sez Who?

The first and foremost important elements making a steel is carbon, and nonmetallics

The next is crystalline structure, like martensite.

Then the distribution of such impurities in the interfaces vs. crystals internals.

Crystals sizes.

Metallic alloying agents were not mentioned until now.

And that is from the top of my head, and I am not a metallurgist. Surely, some were missed.

Go back to school, and learn something, before talking. Hands-on is helpful too.

leveles, I knew I could count on you.

You asked sez who.

That's a fair question.

I am a metallurgist, over 30 years experience. Including Supervising chemical and mechanical testing and metallographic laboratories at USS steel after putting myself through college while working in Blast furnace. I have headed quality and technology for 4 other steel companies. As well as Plant Manager positions.Over 30 years experience in operations, quality, and technology management in the steel industry, balance in advanced manufacturing.

I have provided expert testimony to Dept of Commerce, House ways and means subcommittee on foreign trade, and OMB on technical issues involving product, process, markets, capabilities,regulations and commercial impacts in the steel industry and advanced manufacturing.

Have a nice day.

PS, most of the items you mentioned I have already posted about.

Milo

In that case, please accept my apology, no ifs, no buts.

The only excuse _ whatever it is worth - that it sounded to me as a student's note.

In hindsight, it was not meant for you. My mistake. With the explanation, I hope you do not take it personally.

best regards

No harm, no foul.

Nice to meet you.

Milo

Here in the customs biz where everything gets classified by tariff numbers to identify the goods for customs officers and duty and taxes are applied, there are several categories of iron and steel as defined by the World Customs Organization (WCO).

Below are the definitions as published by the WCO. I am also not a mettalurgist but use these guidelines when classifying iron and steel.

Notes.

1.- In this Chapter and, in the case of Notes (d), (e) and (f) throughout the Nomenclature, the following expressions have the meanings hereby assigned to them:

(a) Pig iron

Iron-carbon alloys not usefully malleable, containing more than 2 % by weight of carbon and which may contain by weight one or more other elements within the following limits:

- not more than 10 % of chromium

- not more than 6 % of manganese

- not more than 3 % of phosphorus

- not more than 8 % of silicon

- a total of not more than 10 % of other elements.

(b) Spiegeleisen

Iron-carbon alloys containing by weight more than 6 % but not more than 30 % of manganese and otherwise conforming to the specification at (a) above.

(c) Ferro-alloys

Alloys in pigs, blocks, lumps or similar primary forms, in forms obtained by continuous casting and also in granular or powder forms, whether or not agglomerated, commonly used as an additive in the manufacture of other alloys or as de-oxidants, de-sulphurising agents or for similar uses in ferrous metallurgy and generally not usefully malleable, containing by weight 4 % or more of the element iron and one or more of the following:

- more than 10 % of chromium

- more than 30 % of manganese

- more than 3 % of phosphorus

- more than 8 % of silicon

- a total of more than 10 % of other elements, excluding carbon, subject to a maximum content of 10 % in the case of copper.

(d) Steel

Ferrous materials other than those of heading 72.03 which (with the exception of certain types produced in the form of castings) are usefully malleable and which contain by weight 2 % or less of carbon. However, chromium steels may contain higher proportions of carbon.

(e) Stainless steel

Alloy steels containing, by weight, 1.2 % or less of carbon and 10.5 % or more of chromium, with or without other elements.

(f) Other alloy steel

Steels not complying with the definition of stainless steel and containing by weight one or more of the following elements in the proportion shown:

- 0.3 % or more of aluminium

- 0.0008 % or more of boron

- 0.3 % or more of chromium

- 0.3 % or more of cobalt

- 0.4 % or more of copper

- 0.4 % or more of lead

- 1.65 % or more of manganese

- 0.08 % or more of molybdenum

- 0.3 % or more of nickel

- 0.06 % or more of niobium

- 0.6 % or more of silicon

- 0.05 % or more of titanium

- 0.3 % or more of tungsten (wolfram)

- 0.1 % or more of vanadium

- 0.05 % or more of zirconium

- 0.1 % or more of other elements (except sulphur, phosphorus, carbon and nitrogen), taken separately.

Nothing like government and commerce to put a fine point on things instead of creating general guidelines...

Milo

It wouldn't surprise me if they asked us to calculate a different rate of tax on each alloying element in the steel..

You are closer than you think. Here in the states they do call out surcharges by grade, and a separate one for manganese, over and above the scrap surcharge... Milo

Thanks for sharing useful knowledge about alloy steel and alloying elements. This information was very useful for me.