FeSiMg

Master Alloy – FeSiMg a précis

Steel Alloy ofFe & C

C = 0.2% to 2.1%

Iron Element

abundant in earths crust

Alloy of Fe, C & Si

Cast Iron

C = 1.7 to 4.3%Si = 0.5 to 3%

Iron-Iron Carbide diagram

Liquid

Austenite

a + Fe3C

d

g+ L

a + g

L + Fe3C

723˚C

910˚C

0% 0.8% ~2% ~3%

a

g + Fe3C

Carbon wt %

Tem

p C Cast IronSteel

Cast Iron Ternary alloy of Fe + C + SiLower Melting point than Steel – Better castabilityLow cost material – use of sand casting

Forms usedPipes / Machines / cylinder heads / cylinder blocks / gear boxes

Blast Furnace

Cast Iron Types

GrayWhite Malleable Ductile

1. Gray Cast Iron

Low ductility – low elongation 0.6%High Thermal Conductivity / Damping Capacity

Gray Iron formsWith slow cooling (viz. heavy castings)High Silicon & Carbon

C Si Carbon

2.5 – 4% 1 – 3% Graphite

2. White Cast Iron

Very High HardnessAbrasion ResistanceBrittle

White Cast Iron Fracture surface is whiteCan be Heat treated

C Si Carbon

1.8 – 3.6% 0.5 – 2% Cementite

3. Malleable Cast Iron

Shock Resistance Ductility & Machinability

Malleable Cast Iron Heat treated White Cast ironThinner CastingsRailway Components

C Si Carbon

2 – 2.6% 1.1 – 1.6% Graphite

4. Ductile Cast Iron

Popular name : SG Iron High Strength – >gray cast ironDuctility 6 to 20%Casting of intrinsic shapes

Ductile Cast Iron Machinability better than steelCrankshafts / disc brake calliperssteering knuckles / Pipe and pipe fittings

C Si Carbon

3 – 4% 1.8 – 2.8% Graphite - Nodules

Steel Production world wide (2009)

250 + 50 - 250 10 - 50 2.5 - 10 < 2.5

Billion

Ton

s

Present Market Potential & Minex Presence

64000MT/Year

30000MT/Year

14000MT/Year

Spheroidal Graphite IronS. G. Iron is ductile than forms of Cast Iron.

Flakes to Nodules formation - addition of nodularizing elements like Mg/Ce

Cast Iron

S G Iron

Iron C Si Mn S P Carbon form

Ductile 3 – 4 % 1.8 – 2.8 % 0.2 – 0.9% 0.03 % max 0.1% max Nodules

Applications of S G Iron

Various forms of Mg addition

Pure Magnesium

Nickel Magnesium alloy

Fe-Mg briquettes.

Magnesium-Ferro Silicon alloy

FeSiMg Production routes

FeSi melting & Mg ingot Plunging

FeSi & Mg melting in Induction Furnace

Carbo-thermic reduction of SiO2 using EAF and Treatment of Si Melt with Fe & Mg

Magnesio-thermic reduction of Quartz and Mill scale – Not followed

FeSiMg – Microscopic Structure

Nodularizing – Mechanism Nodularizing is a simultaneous desulphurizing & deoxidizing

Mg + S= MgS --------- Desulphurization Mg + O = MgO ------- DeoxidationMg + Si + 3O = MgSiO3

2Mg + Si + 4O = Mg2SiO4

After this the growth of graphite proceed as nodules

Graphite

Orthorhombic Irregular shape

Increased under cooling

Spheroidal

As the solidification velocity increases with time the graphite flakes are converted to spheroids

After Mg Treatment

Various forms of Mg addition Pure MG addition: Addition of Mg produce violent reaction, and addition is made above the boiling (1103°C) temperature. The obtained recovery is very low (20-50%).FeSiMg addition: Addition of FeSiMg with the presence of Si, Ca & Ce gives less violent reaction. Si increase the Mg solubility. Recovery in this addition 60-90%.

Inoculation

Silicon is graphite stabilizer in Cast Irons

Provide nucleation sites for the carbon to precipitate as graphite rather than Fe3C

Increases No. of nodules leading to finer structure of Cast Iron

Role of Alloying Elements- FeSiMg alloy

Mg

12

Magnesium allows to precipitate graphite in the form of nodules

RE

58

Rare earth reduces the negative effects of trace elements like Ar/Bi/Ti/Pb, forms intermetallic, also reduce sulphur

Ca

20

Reduces the reactivity of Mg and thus minimizing the fumes emission

Initiate the modification process by reacting with S and O forming sulfide and silicate phase

Role of Alloying Elements- FeSiMg alloy

Al

13

Aluminium in reduces undercooling and shrinkage tendency

Base aluminum is low, a small amount of aluminum improves inoculation

FeSiMg Alloy Treatment Methods

Sandwich Cover Process

Plunger Process

Tundish Cover Process

Inmould Process

Cored Wire Treatment Process

FeSiMg / Mg wire

Treatment ladle (covered)

Sources & Effect of impurities Elements Effects Sources Max Limit %

Lead Can reduce tensile Strength, Promotes pearlite

paints, freecuttingsteels, nonferrous alloys,

0.002

Antimony Degenerate Graphite nodules, some spheroids accumulations torn into small pieces.

white metal, solder, some pig irons

0.005

Bismuth Promotes carbides and undesirable graphite forms that reducetensile properties

Bismuth containingmolds and core coatings

0.002

Titanium Promotes undercooled graphite. Combines with nitrogen to neutralize its effects

Some pig irons, steel scrap,

0.05

Aluminum Promotes hydrogen pinhole defects,Neutralizes nitrogen

ferrous alloys,inoculants, scrap

0.6

Projects Carried By R&D

Redesign the ladle lining with insulation and high Al2O3 refractory and SiC refractory

Trials for refining FeSi-50%

Trial for reduction of slag sticking to F/C wall in imported FeSi Melting process

Effect of cooling rate on FeSiMg alloy

Problems faced during production & process

Melting

Alloying

Sizing

Casting

Slag Sticking to liningFeSi refiningMg losses – Skull formation

Spillage lossesMould erosionSlag entrapped mtrExcessive undersizeCapsule size generation

Thank you