Minex Metallurgical Co. Ltd.Cored WiresPure Magnesium & FeSiMg For Iron Foundry

Spheriodiser Cored WirePURE MAGNESIUM & FeSiMg CORED WIRE FOR IRON TREATMENT WITH IMPROVED RECOVERYToday majority of ductile iron castings made throughout the world are produced using ladle metallurgy practices with FeSiMg alloys and cored wire injection. It is estimated that FeSiMg alloys are used in 65 percent of all ductile iron produced worldwide. The supply of domestically produced FeSiMg becomes important in assessing whether this important raw material will be available in sufficient quantities to sustain the forecasted growth.High performing FeSiMg alloys are to be manufactured to sustain the projected growth of ductile iron. Today the concern with automation, cost, consistency, improved recovery and reduced (fumes) environmental hazards in work space compel more and more cast-house to adopt cored wire injection method for ladle inoculation/spheroidization treatment. Minex has established specialized plants to provide a consistent and quality service to the customers. Minex-Kalmeshwar certified to Integrated Management System (viz. ISO-9001-2008, ISO-14001-EMS, OHSAS-18001) is one of the major Pure Mg and FeSiMg cored wire production plants in the India. Minexs consistency has seen the most quality oriented foundries in India and abroad turn to Minex as their preferred supplier. Further news and development may be found on our website www.minexindia.comProduct Introduction The valuable characteristics of magnesium addition to iron have been known for the purpose of nodule formation and improving the mechanical properties. Addition of magnesium promotes transformation of graphite flakes to nodules during solidification of iron melt due to increase in the surface tension. Today, magnesium, pure or in a form of master alloy, is the most effective nodularizing agent used by the foundry industry to produce quality ductile iron castings. However, the usage of magnesium for treating of liquid iron has a number of difficulties caused by specific physical properties of magnesium. This includes low melting and boiling temperatures (1202F/650C and 2025F/1107C respectively), low density (1.738 g/cm3 vs. 7.0g/cm3 of liquid cast iron), and low solubility in liquid iron (about 0.001% wt at 650C). As a result, the introduction of magnesium or magnesium containing alloy into liquid iron is typically accompanied by significant flame and fume called 'pyro effect', which makes the magnesium treatment process highly violent and unsafe. The later caused significant magnesium losses due to magnesium burning, and hence reduction of residual magnesium content in solidified castings. Certain magnesium losses are also incurred due to magnesium reaction with elements contained in liquid iron: first, with sulphur, and second with oxygen. Cored wire in particular a magnesium or FeSiMg core is surrounded by a steel sheath or jacket have found wide application in the treating of molten ferrous metal for inoculation, desulphurization and spheroidization. The pure magnesium and FeSiMg cored wire is manufactured with special grade steel sheath so as to introduce magnesium into the steel bath at greatest possible depth so as to make use of the increased pressure from ferrostatic head and thus to prevent magnesium from evaporating.Pure magnesium metal granules or FeSiMg powder is filled in high grade quality cold rolled steel strip for higher penetration depth of magnesium & improved magnesium recovery. Cored wire is injected with aid of wire injection system in iron melt. The Pure Magnesium and FeSiMg cored wire specifications are as follows:

FeSiMg Cored Wire SpecificationsChemical composition of Mg-FeSi powder (%)

GradeMgSiAl (Max)CaReOthr (Max)Fe

FeSiMg 2018-2045-460.51-31-31Bal

FeSiMg 20 (WRe)20-2533-380.81-31 max1Bal

FeSiMg 3030-3225-330.81-30.5 -31Bal

FeSiMg 4038-4222-300.81-20.5-31Bal

FeSiMg 5050-5225-300.81-31-3.51Bal

FeSiMg 8078-827-110.81-31-31Bal

Powder specificationStrip Specification

GradeDensity (gm/cc)Melting Point (C)Boiling Point (C)Size (mm)GradeDiameter (, mm)Thickness (mm)

FeSiMg4.3 4.8910- 1225--1.4+0.3EDD IS 51390.50.40 0.03

Fe7.815402860-0.6+0.045130.20.400.03

Si2.414123270-1.4+0.016

Mg1.746501090-1.4+0.212

Wire Characteristics

GradeFeSiMg 20FeSiMg 20 (W-Re)FeSiMg 30FeSiMg 40FeSiMg 50FeSiMg 80

Diameter (, mm)90.590.590.590.590.590.5

ShapeRoundRoundRoundRoundRoundRound

Powder Fill (gm/mtr)1201011510110101001095107010

Coil Specification (Flipping Coil Horizontal & Vertical)

Details9 mm 9 mm 9 mm 9 mm 9 mm 9 mm Coil Identification

20% Alloy20% W-Re Alloy30% Alloy40% Alloy50% Alloy20% Alloy

F1-05F2-05F3-05F4-05F6-05F7-05

Powder Weight (MT)0.5000.5000.5000.5000.5000.500All coils are color coded and fixed with a detailed sticker clearly displaying details such as coil no., powder content, strip weight, gross weight density & length. A fluorescent sticker displays the name of the product in bold letters on the outer diameter of the coil.HandlingNo metal sling, chain or rod is to be used across the ID of the coil for handling as it may damage the coil. Use only polyester, synthetic slings, fork lift/tractor to handle the coil. The pallet is an integral part of the coil and it is to be removed till the coil is consumed.Shelf LifeFollow the shelf life period specified by MINEX

Strip Weight (MT)0.5050.4200.5950.6400.6950.850

Net Weight (MT)1.0050.9201.0951.1401.1951.350

Length (Mtrs)416643854545500055557142

Internal Diameter (mm)650650650650650650

External Diameter (mm)100010501050105010801200

Height (mm)630630630630630630

Pure Magnesium Cored Wire SpecificationsChemical composition of pure Magnesium powder (%)

GradeMgOther (Max)

Mg 100982.0

Powder specificationStrip Specification

GradeDensity (gm/cc)Melting Point (C)Boiling Point (C)Size (mm)GradeDiameter (, mm)Thickness (mm)

Mg1.746501090-1.4+0.212EDD IS 51390.50.9 0.03

Wire Characteristics

GradeDiameter (, mm) ShapePowder Fill (gm/mt)

Ca9 0.5Round60 10

Coil Specification (Flipping Coil Horizontal & Vertical)

Details9 mm Coil Identification

F8-04

Powder Weight (MT)0.400All coils are color coded and fixed with a detailed sticker clearly displaying details such as coil no., powder content, strip weight, gross weight density & length. A fluorescent sticker displays the name of the product in bold letters on the outer diameter of the coil.HandlingNo metal sling, chain or rod is to be used across the ID of the coil for handling as it may damage the coil. Use only polyester, synthetic slings, fork lift/tractor to handle the coil. The pallet is an integral part of the coil and it is to be removed till the coil is consumed.Shelf LifeFollow the shelf life period specified by MINEX

Strip Weight (MT)0.770

Net Weight (MT)1.170

Length (Mtrs)6153

Internal Diameter (mm)650

External Diameter (mm)1140

Height (mm)700

Cored Wire Injection ProcessOver the last few years, cored wire has increases its popularity of spheroidization of ductile iron and manufacturing of compacted graphite (CG) iron. The current concern with automation, cost, consistency and large amount of fumes coming in work space from iron treatment ladle makes more and more cast shop adopt cored wire method. The treatment effects can be equal to or higher than other methods if it is applied adequately. Therefore there is no surprise that cored wire is adopted widely.Normally the Cored Wire is a steel tube filled with granular Magnesium or FeSiMg alloy or mixture of these. (as shown in fig.)a)b)

Fig. 1: a) Tubes filled with Mg/FeSiMg b) packed coil of cored wire

Process Parameters affecting cored wire injection Sulphur content of the Base Metal to be treated ( Sf ) Treatment Temperature Wire feed rate and treatment time Geometry of treatment ladle Quantity of the Metal to be treated. Composition of Mg cored wire Desired percentage of Magnesium in the Metal Free board of about 300mm Geometry of the wire guide tubes Design of treatment station

Sulphur content of the Base MetalMg Cored wire injection process is very flexible with Sulphur content, because it can treat base iron with higher S composition as combined desulphurization and Mg treatment of cupola iron with S range 0.05 to 0.15% (preferably S 0.08%) and base iron with low S composition as Mg treatment of electrically melted iron with S content < 0.03% (preferably S < 0.015%)But always keep in mind, any point of increase of Sulphur in iron will result in high wire consumption, more cost and more slag. And if Sulphur is very low < 0.01% then special attention has to be paid in inoculation of the melt. Wire feed rate and treatment timeWire feeding speed is very important parameter in Mg wire injection process, as it greatly influences the desulphurization and spheroidization of iron melt. The optimum wire injection speed is such that it release the Mg/FeSiMg powder into a certain depth (near bottom of ladle) of iron melt, where Mg changes to vapor bubbles under sufficient ferrostatic head which raise slowly and reacts with iron melt from bottom to head. Fig. 2: The effect of different wire feeding speed on (a) Mg Yield (b) desulphure rate (c) drop in temp.Condition: intial S-0.028%, feeding speed-15m/min, liquid wt-500 Kgs, H/D of ladle 2:1

The release of Mg powder near the bottom can over come the weakness of Mg as low density, high vapor pressure, low boiling point, active chemical property etc; and leads to higher Mg recovery. Too high or too low speed will reduce the effect of treatment, additonally the temperature drops are below 80C.At too low speed the wire is melted near the surface of the melt and Mg is lost near surface (as shown in fig. 3.b). And at too high speed there are two reasons for lower yield of magnesium; (a) the wire does not melt at the bottom and comes out near surface of melt. Hence release of Mg much above the level of bottom of the melt or (b) at higher speed the rate of release of Mg near bottom is very high. It leads to high vapor pressure of Mg bubbles which rise at high speed (as shown in fig. 3.a). If the feeding speed and treatment temperature are not well controlled, the treatment effect will deteriorate seriously and sometimes explosion will happen dangerously in treatment ladle if the feeding speed is too high.

a)b)c)

Fig. 3: The effect of different wire feeding speed (a) Too High Speed (b) Too low speed (c) Normal speed

Desired percentage of Magnesium in the Metal and Treatment costThe following formula shows the basic calculation method for wire length and Mg recovery. Initially certain assumptions has to be met, the effect of temperature is being ignored in order to calculate the wire requirement for new applications:Empirical Formula:

Where S= Opening Sulphur Final Sulphur Mg %= Residual Mg content Mg Rec. = Recovery of Magnesium, for all practical

For example: Calculating quantity of cored wire to be injected and cost of treatment as practiced at one of the renowned SG iron foundry in India is as follows:The existing parameters are:Treatment ParametersQuantity /Units

Quantity of Metal treated:1000 kgs

S (i) (Initial Sulphur):0.02%

S(f) (Final Sulphur):0.007%

S (S (i) -S(f) ) :0.013%

Mg (f):0.04

Cored Wire:Mg 20 with 20% Mg

Wire Density:120 +/-10 gms/Mtr

Treatment :1400 1450C

With practical consideration it is found that Mg recovery is more than 45%.

Length of Wire (mtr) = 46 mtr (i.e. 5.5 Kgs of Powder)

Cost of Treatment /MT of LM = 5.5 kgs x Rs.180/-= Rs.990/- /MT of LM

Although the cost comparison with other process as sandwich or other, is very difficult, because type/ grades of alloy, cost of alloy are used and recovery of Mg etc. Suppose using FeSiMg 7% Mg alloy is used to treat above metal and the Mg recovery is 45-50% the alloy consumed can be calculated using the following empirical formula, for all parameters given above as change in sulphur S, final Mg in melt Mgf

= 1000 x (0.04 + 0.76(0.013)) / (7x 0.45)= 15.8 KgsIf assumed price of FeSiMg of Mg 7% is more than Rs. 90/-. Thus the price of treatment will be 15.8 x 90 = Rs. 1422 /- . Thus the Mg treatment of iron with cored wire injection is cheaper than sandwich process. This is one of the examples, but the cost of treatment varies from foundry to foundry because it depends on various parameters. Cost of one foundry cannot be applied to another foundry, it has to be well experimented. Advantages Various advantages of cored wire injection process are summarized below according to above discussion. Improved Metallurgical results achieved by precise addition of Mg Cored Wire resulting in close control of the residual Mg in the iron. Very flexible with any composition of iron, especially with Sulphur which is very difficult to treat with other process Lower loss than alloy process. Better efficiency. Reliable and consistent process. Ease of operations. Less slag formation and ladle buildup Less slag inclusions in the castings. Favorable cost of treatment. Desulphurization and Spheroidization can be done simultaneously. Reduced labor requirements. Less capital investment and treatment cost. Harmless to the environment as emission can be controlled and drawn off easily. Process supports futuristic alloy like CG Iron production. Scope for Total Automation