Some effects of Alloying elements in Steel

Alloying additions are commonly added to steels to;

  • increase hardenability,
  • improve strength,
  • improve mechanical properties (at operating temperature),
  • improve toughness for a given strength or hardness,
  • increase wear resitance,
  • improve magnetic properties.

Increasing the hardenability means that pearlite transformation will be delayed to longer times. This means it is easier to obtain martensite or bainite on cooling, or by isothermal holding after cooling past the pearlite start temperature.

Classification of alloying elements by Bain in The Alloying Elements in Steel

Dissolved in Ferrite

Ni, Si, Al, Zr, Mn, Cr, W, Mo, V, Ti, P, S (?) Cu.

Nickel, silicon, aluminium, zirconia, manganese, chromium, tungsten, molybdenum, vanadium, titanium, phoshorous, sulphur and copper.

Combined in Carbide

Mn, Cr, W, Mo, Nb, V, Ti.

Manganese, chromium, tungsten, molybdenum, niobium, vanadium, titanium.

B

Boron can be present in borocarbides, or as borides.

In Nonmetallic Inclusions

SiO2, MxOy, Al202, etc

ZrO, MnS, MnFeO, MnO, SiO2, CrxOy

VxOy, TixOy, MnFeS, ZrS

Special Intermetallic Compounds

Ni-Si Compound (?), AlxNy, ZrxNy

VxNy, TixNyC2, TixNy

Elemental state

Cu above 0.8%

Pb (?)

The effects of common alloying elements in steel was summarised as follows (data from ‘Metals Handbook’ 1948, American Society for Metals, Metals Park, Ohio.

Al – Aluminium

Solid Solubility

In Gamma Iron (austenite)

1.1 % (increased by C)

In Alpha Iron (ferrite)

36 %

Influence on ferrite

Hardens considerably by solid solution.

Influence on austenite (hardenability)

Increases hardenability mildly, if dissolved in austenite.

Influence exerted through carbide

Carbide forming tendency

Negative (graphitizes).

Action during tempering

Principal functions

  • Dexodises efficiently.
  • Restricts grain growth (by forming dispersed oxides or nitrides).
  • Alloying element in nitriding steel.

Cr – Chromium

Solid Solubility

In Gamma Iron (austenite)

12.8 % (20 % with 0.5 C)

In Alpha Iron (ferrite)

Unlimited

Influence on ferrite

Hardens slightly; increases corrosion resistance.

Influence on austenite (hardenability)

Increases hardenability moderately.

Influence exerted through carbide

Carbide forming tendency

Greater than Mn; less than W.

Action during tempering

Mildly resists softening.

Principal functions

  • Increases resistance to corrosion and oxidation.
  • Increases hardenability.
  • Adds some strength at high temperatures.
  • Resists abrasion and wear (with high carbon).

Co – Cobalt

Solid Solubility

In Gamma Iron (austenite)

Unlimited

In Alpha Iron (ferrite)

75 %

Influence on ferrite

Hardens considerably by solid solution.

Influence on austenite (hardenability)

Decreases hardenability as dissolved.

Influence exerted through carbide

Carbide forming tendency

Similar to Fe.

Action during tempering

Sustains hardness by solid solution.

Principal functions

  • Contributed to red-hardness by hardening the ferrite.

Mn – Manganese

Solid Solubility

In Gamma Iron (austenite)

Unlimited

In Alpha Iron (ferrite)

3 %

Influence on ferrite

Hardens markedly; reduces plasticity somewhat.

Influence on austenite (hardenability)

Increases hardenability moderately.

Influence exerted through carbide

Carbide forming tendency

Greater than Fe; less than Cr.

Action during tempering

Very little in usual quantities.

Principal functions

  • Counteracts brittleness from sulphur [by forming MnS sulphides).
  • Increases hardenability inexpensively.

Mo – Molybdenum

Solid Solubility

In Gamma Iron (austenite)

~3% (8% with 0.3% C)

In Alpha Iron (ferrite)

37.5% (less with lowered temperature)

Influence on ferrite

Provides age hardening system in high Mo-Fe alloys.

Influence on austenite (hardenability)

Increases hardenability strongly (Mo > Cr).

Influence exerted through carbide

Carbide forming tendency

Strong; greater than Cr.

Action during tempering

Opposes softening, by secondary hardening.

Principal functions

  • Raises grain-coarsening temperature of austenite.
  • Deepens hardening.
  • Counteracts tendency toward temper brittleness.
  • Raises hot and creep strength, red-hardness.
  • Enhances corrosion resistance in stainless steel.
  • Forms abrasion resisting particles.

Ni – Nickel

Solid Solubility

In Gamma Iron (austenite)

Unlimited

In Alpha Iron (ferrite)

10% (irrespective of carbon content)

Influence on ferrite

Strengthens and toughens by solid solution.

Influence on austenite (hardenability)

Increases hardenability mildly, but tends to retain austenite at higher carbon contents.

Influence exerted through carbide

Carbide forming tendency

Negative (graphitizes).

Action during tempering

Very little in small percentages.

Principal functions

  • Strengthens unquenched or annealed steels.
  • Toughens pearlitic-ferritic steels (especially at low temperature).
  • Renders high-chromium iron alloys austenitic.

P – Phosphorus

Solid Solubility

In Gamma Iron (austenite)

0.5%

In Alpha Iron (ferrite)

2.8% (irrespective of carbon content)

Influence on ferrite

Hardens strongly by solid solution.

Influence on austenite (hardenability)

Increases hardenability.

Influence exerted through carbide

Carbide forming tendency

.

Nil

Action during tempering

Principal functions

  • Strengthens low-carbon steel.
  • Increases resistance to corrosion.
  • Improves machinability in free-cutting steels.

Si – Silicon

Solid Solubility

In Gamma Iron (austenite)

~2% (9% with 0.35% C)

In Alpha Iron (ferrite)

18.5% (not much changed by carbon).

Influence on ferrite

Hardens with loss in plasticity (Mn Influence on austenite (hardenability)
Increases hardenability moderately.

Influence exerted through carbide

Carbide forming tendency

Negative (graphitizes).

Action during tempering

Sustains hardness by solid solution.

Principal functions

  • Used as a general purpose deoxidiser.
  • Alloying element for electrical and magnetic sheet.
  • Improve oxidation resistance.
  • Increase hardenability of steels carrying non-graphitising elements.
  • Strengthens low-alloy steels.

Ti – Titanium

Solid Solubility

In Gamma Iron (austenite)

0.75% (1% with 0.2 % C)

In Alpha Iron (ferrite)

~6% (less with lowered temperature)

Influence on ferrite

Provides age hardening system in high Ti-Fe alloys.

Influence on austenite (hardenability)

Probably increases hardenability very strongly as dissolved, the carbide effects reduce hardenability.

Influence exerted through carbide

Carbide forming tendency

Greatest known (2% Ti renders 0.5% carbon steel unhardenable).

Action during tempering

Persistent carbides probably unaffected. Some secondary hardening.

Principal functions

  • Fixes carbon in inert particles;
  • reduces martensitic hardness and hardenability in medium Cr steels.
  • prevents formation of austenite in high Cr steels.
  • prevents localised depletion of chromium in stainless steel during long heating.

W – Tungsten

Solid Solubility

In Gamma Iron (austenite)

6% (11% with 0.25C)

In Alpha Iron (ferrite)

33% (less with lowered temperature)

Influence on ferrite

Provides age hardening system in high W-Fe alloys.

Influence on austenite (hardenability)

Increases hardenability strongly in small amounts.

Influence exerted through carbide

Carbide forming tendency

Strong.

Action during tempering

Opposes softening by secondary hardening.

Principal functions

.

  • Forms hard, abrasion resistant particles in tool steels.
  • Promotes hardness and strength at elevated temperature.

V – Vanadium

1 (4% with 0.2% C)

Solid Solubility

In Gamma Iron (austenite)

Unlimited.

In Alpha Iron (ferrite)

Hardens moderately by solid solution.

Influence on ferrite

Unlimited.

Influence on austenite (hardenability)

Increases hardenability very strongly as dissolved.

Influence exerted through carbide

Carbide forming tendency

Very strong

Action during tempering

Maximum for secondary hardening.

Principal functions

  • Elevates coarsening temperature of austenite (promotes fine grain).
  • Increases hardenability (when dissolved).
  • Resists tempering and causes marked secondary hardening.
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33 Responses

  1. Dear Sir
    I need some more information about heat treatment(hardening and tempering) of 32NiCrMo12-5.
    mechanical properties(required) :
    UTS=min1100Mpa,YP=min980Mpa,EL=min13%,RA=min355
    Thankyou very much

  2. Dear sir,
    I need to know effect of Cu that diffuse into the steel and
    Aluminium. I’m looking for reason to support my Project that
    about diffusion of copper is be a cause of crack in mold.
    Thank you very much

  3. It’s better If you give me information about effect both of Cu and Zn

    ^^ Thanks again

  4. Dear Sir
    If its possible please give me some information about the effects of Cu on weldability of steel specually carbon steel and low alloy steel. I have heard that it can improve weldability but I have found nothing about it.
    Thanks alot

  5. […] I previously made a post Some effects of alloying elements in steel. […]

  6. Hi Sir,
    I Have one query. In alloy steel how does alloying elements participate itself in solid solution and carbides in Austenite and ferrite.

  7. Hi Sir ,
    I have more information related effect of alloying element Si and Mn
    in Steel give the information mechanical properties effect .

  8. You should tell people about it,

  9. Dear Sir

    How the Mn & Si influences the viscosity and Surface tension of low carbon (.07-0.09 %) steel

  10. When solid, not very much.

  11. Dear sir,
    Hi,
    If it’s possible, please give me some information about the effects of alloying element on bainite morphology in low carbon steel and also introduce some refereces about it.
    thank you very much.
    regards

  12. Start with the Book bainite in steels. You can find it at http;//www.msm.cam.ac.uk/phase-trans/

  13. Dear friends,
    As Asked by Mr P.K. Pandey, I have to submit some Metallurgical facts:
    Si & Mn in Steel melts have a definite effect on Viscocity of Low Carbon Steel. Apart from Shrinkage behaviour and Banding tendencies, Viscocity of steel is also affected by these elements.
    Mn Increases Viscocity and Silicon has a little effect on Viscocity. However, Surface tension of steel is reduced by manganese and is increased by Si addition

    Regards

  14. In AISI 1070 steel,
    ( Carbon, C 0.650 – 0.750 % Manganese, Mn 0.600 – 0.900 %
    Phosphorous, P <= 0.0400 % <= 0.0400 %
    Sulfur, S <= 0.0500 % <= 0.0500 % )

    If Mn increases to 1.25% to 1.5% ,will the steel more suseptible to cracking during quenching.
    Section thickness 4 to 6 mm.
    References

  15. Dear Sir

    I need to know the effect of Cu in steel, looking from the corrosion point of view, how it affects the steel if some Cu particles diffuse into it.

    Thank you very much

  16. I have a stamped part that I run in a 800 ton press it is a JIS G3113 SAPH 440 material. One coil takes 600 tons of force to form the 3mm thick part. The carbon content is 0.06, Mn is 0.41, P =0.013. A second coil only takes 400 tons to form the same part. It is also a JIS G3113 SAPH material but the carbon content is 0.056, MN is 0.21 and P = 0.006. I know that the Mn and P will make the material harder but both steels fall within the spec for JIS G3113. Would the doubling of Mn and P change the tonnage required to stamp the part by this much?

    Thank You,

  17. dear sir
    i need some information about prevent eutectic carbide network formation in 12% cr steel casting by another alloying element(my analays=c=1.2-1.4 cr=11-13 mo=0.2-0.4 ni=0.2-0.4 )or break network carbid after formation in solidification by heat tretment
    please help me
    my email adress: alloymail@gmail.com

  18. Dear sir,
    thanxxxx a lot…

  19. Hi,

    I am curious about increase Aluminum Solubility in Austenite.
    Would you have any references related to Alumnium Solubility Vs Carbon %wt.

    Thank you.
    Vik

  20. Dear All,

    Hi, please give me information about SAPH 400 steel properties.

    thanxxxx b4

  21. I don’t know about it, you should try seaching the web, or supplier literature for that grade.

  22. i was effort to searching the web but i didn’t found SAPH 400 steel properties… but i found using the SAPH 400.

  23. if you search “saph400 properties” you can find some information like composition, UTS=> 400 MPa, yield strength, elongation, etc, from different suppliers.

  24. hi sir,
    this topic is very important as for some working with materials has to know thier properties and the effect so as to know which is suitable for the job.I am very greatful to see such a topic like this on line.
    Thanks for the lesson and i will always see in to the future of this site.

  25. hi dear sir
    I need information about wett ability of alloys in carbon steel and their effects

    best regards

  26. Girnaralloys is a leading Manufacturers & Exporters of Niresist Castings, Nihard Castings, Alloy Steel Castings, Ni-resist Castings & Ni-hard Castings in India.

  27. Dear sir,
    I have some problem that i would like find the answer
    that now i have already tested the tensile testing of cast steel (SC 1020) by using the test piece with 8 mm Dia. testing result is not passed (UTS : spec 460 Mpa. result : 550 Mpa. while El : Spec 22 Min, Result 13 )

    who can sugest me that should i do my
    casting process or test piece.
    best regard ,
    S. Chaichana

  28. You should check what is recommended heat treatment. It might be possible to achieve the elongation by temper heat treatment, but I don’t know off hand what would be suitable temperature/time. You could try heating to 250 C for 2 hours, but best to find the established heat treatment, otherwise might hit unexpected problems. (For example tempering at some temperature may lead to embrittlement).

    If you bought that steel grade I think the supplier should be able to tell you. If you have melted it yourself and performed recommended heat treatment you might also want to check the composition is as specified.

  29. Sir,

    I have MTC here with Specification ASTM A 572 M S345 Type 1. But the values of Columbium, Vanadium, Titanium & Nitrogen in the chemical properties are all within the range given in Table 3 of the said specification. For these reason it shows that the MTC is not specific for Type 1, it is applicable to all Type in Table 3.
    Please provide explanation if this MTC is Acceptable or not. I can’t see clear explanation from ASTM 572 with regards to this type of MTC.

  30. Hi, I don’t really understand what is MTC?

  31. dear sir.
    why most elements have high affinity for carbon and also for oxygen?
    not clear to me.
    thank you

  32. Can anybody tell me what is the maximum level of tungsten allowed as trace element in low alloy steels like AISI 4142, 37Cr4 and what would be effect if the amount is more than this level;

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