MATERIAL LOGAM

Classification of MetalsFERROUS NON FERROUS

STEEL CAST IRONLIGHT

METALSHEAVY

METALS

CARBON STEEL

ALLOY STEEL

Low Carbon

Medium Carbon

High Carbon

Low Alloy

High Alloy

HSLA

White Cast Iron

Gray Cast Iron

Ductile Cast

Malleable Cast Iron

Al

Mg

Ti

Cu

Pb

Ni

etc etc

Ferrous Metals• The ferrous metals are based on iron.• The ferrous metals of engineering importance are

alloys of ferrous and carbon which are then classifiedinto steel and cast iron.

• The principal ore used in the production of steel andiron are :- Haematite (Fe2O3)- Magnetite (Fe3O4)- Wustite (FeO)

• These ores are then crushed, screened and shapedinto pelet, briquette or sintered.

Generic Fe-based metals

Steels Processing• The production process of steels are broadly divided

into two steps i.e :- Iron making through the reduction of iron ores(pelet, briquette and/or sinter)- The refining process to reduce or eliminate some ofthe elements such as carbon, oxygen, sulphur andphosphor to a certain level.

• The iron making may be performed either by indirectreduction or direct reduction of the iron ores.

• The refining could be done through various methodsand equipment such as BOF, EAF, LD, SM, Thomasconverter etc.

• The refining process result in molten steel.

• This molten steel are then either cast intoingots or into slab, bloom and billet bycontinuous casting.

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I. Iron & steel Making Through Indirect Reduction Process

• The process of directly reducing the iron ore in solid form by reducing agents is called direct reduction.

• The iron resulted from this process is called sponge iron.

• There are four reducing agents that can be used :

- Coal, coke or charcoal.

- By electrolytic process

- By thermal decomposition of iron carbonyl [ Fe3(CO)5]

-gaseous such as CO or H2 HYL Process

II. Iron & steel Making Through Direct Reduction Process

• The HYL process involves the batch reduction ofhigh grade iron ore in retorts by reformed naturalgas.

• The reducing gas is produced from natural gas(CH4) or coal. The reducing gas is a mixturemajority of hydrogen (H2) and carbon monoxide(CO) which acts as reducing agent.

• The sponge iron produced by this directreduction process has a lower C content than thepig iron.

Direct Reduction using gas –HYL Process

Iron ore is reduced in solid state at 800 to 1,050 °C (1,472 to 1,922 °F) either by reducing gas (H2+CO) or coal.

CH4 + H2O CO + H2

Advantages :

•operating costs of direct reduction plants arelow compared to integrated steel plants.

•iron can be obtained at a lower furnacetemperature, only about 1,100°C or so

Reduction reactions :

Fe2O3 + 3H2 2Fe + 3H2O

Fe2O3 + 3CO 2Fe + 3CO2

Iron carbide is also formed by the combinationof carbon with metallic iron from the reducedproduct:

3Fe + CH4 Fe3C + 2H2

3Fe + 2CO Fe3C + CO2

Fe or

• Sponge iron was a spongy mass of coalesced granules of nearly pure iron intermixed with slag.

• This spongy mass iron was then hammered while still hot from smelting operation to expel most of the slag and compact the mass.

• By repeated heating and hammering, the iron was further freed of slag and forged into the desired shape.

Refining- Basic Oxygen Furnace

C + O2 CO2

MnSi + O2+CaO + FeO slagP

BOF sequence

Electric Furnace Steel MakingAlthough integrated steel plants use oxygen-blownsteelmaking vessels, many smaller steelmakingoperations rely on return scrap steel (versus ironore) as a primary source of material. These furnaceswere originally considered appropriate for theproduction of tool and alloy steels, but they are alsoable to produce low-carbon steels of high quality.

One difficulty is that residuals, such as copper and tin in return scrap, are not diluted with a virgin hot-metal source in electric furnace steelmaking

Ingot

• While steel is still molten, it is poured into a mold. Themold may be a square, rectangle or round. The metalbecomes an “ingot” in the mold.

• They can weigh 100 lbs to 40 tons.• The ingot will be removed from the mold and heated

uniformly to be rolled or formed into a final product.• HOWEVER – While the molten metal cools, or solidifies,

gasses evolve and can affect the quality of the steel.This leads to three types of steel: Killed Steel, Semi-Killed Steel, and Rimmed Steel.

Killed Steel – This is a fully deoxidized steel, and thus,has no porosity.– This is accomplished by using elements like aluminum

to de-oxidize the metal. The impurities rise and mixwith the slag.

– It is called killed because when the metal is poured ithas no bubbles, it is quiet.

– Because it is so solid, not porous, the ingot shrinksconsiderably when it cools, and a “pipe” or “shrinkagecavity” forms. This must be cut off and scrapped.

Killed-Semi killed-Rimmed Steel

Semi-Killed Steel: This is practically the same askilled steel, with some minor differences.– It is only partially de-oxidized, and therefore, is a

little more porous than killed steel.– Semi-Killed does not shrink as much as it

cools,so the pipe is much smaller and scrap isreduced.

– It is much more economical and efficient toproduce.

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Killed-Semi Killed-Rimmed Steel

Rimmed Steel: This is produced by adding elements like aluminum to the molten metal to remove unwantedgases. The gasses then form blowholes around the rim.

– Results in little or no piping.– HOWEVER, impurities also tend to collect in the center of the ingot, so products or rimmed steel need to be inspected and tested.

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**Refining

Killed-Semi killed-Rimmed Steel

Type of steelsI. According to the manufacturing process

- Wrought steel- Cast steel

II. Based on their composition- Plain carbon steel- Alloy steel

III. Based on its characteristics and application- Structural steel- Corrosion resistant steel- Heat resistant steels- Tool steels- Spring steels, etc

WROUGHT STEEL• Wrought steel is produced by rolling or forging

process.

• The process may be performed when the steel is inan ambient temperature or in the elevatedtemperature.

• The process performed in an ambient temperature iscalled cold working process

• Whereas the hot working means the process that isperformed in an elevated temperature

• Continuous casting 1

• Continuous casting 2

• Bloom

Processing of solid wrought steelHot Rolling

It is carried out at Austenite phase (800oC – 1200oC)

( 1200oC ~ 1100oC )

( 900oC ~ 800oC )

VideoHeating of blooms

Cold Rolling

• Cold rolling is applied to produce thin rolled steel products

• It results in better surface quality of steel than can be produced by hot rolling.

• Cold rolling increase the hardness and yield strength, reduce ductility and formability.

• It is also introduces the specific texture components as associated with thickness reduction that can be enhanced by annealing

Annealing

• Annealing removes the work hardening introduced by rolling and thus restore formability.

Types of Wrought Steels

1. Unalloyed wrought steels

2. Alloyed wrought steels

Unalloyed wrought stees consist of :

- Engineering steels / machinery steels / structural steels.

- High quality/high strength steels

- High grade /high purity steels

Structural or Machinery Steels

• Known as “st” (DIN) steel. For example st 37-2, means :- It is a structural steel which has minimum tensile strength of 37 Kg/mm2 and the elongation of 2%.

• These steels are grouped as low carbon steel according to their carbon level range between 0,06% and 0,2%.

• These steels are rolled and shaped into bar,sheet,plateand profils.

• Their strength increase along with the carbon content. • The higher the carbon content the greater the strength of

steel but its ductility and formability will decrease.

• These steels obtain their high strength by heat treatment process which are normalizing, quenching and tempering.

• These steels are generally designated as “C” steels. For example C45 (DIN) which means a high quality steel with the carbon content of 0,45%.

High Quality Steels

High Grade/high purity Steels• These steels are generally designated as “Ck” (DIN)

steels. For example Ck10 which means a high purity steel with the carbon content of 0,1%.

• These steels contain less P and S than high quality steels.

• These are types of constructional steels with the addition of P and S for improving its machinability.

• The heat treatment process are commonly applied to these steels following the machining process.

Rephosporized/Resulfurized steels

CAST STEEL1. Make the pattern out of Wood , Metal or Plastic.2. Prepare the necessary sand mixtures for mould and core

making.3. Prepare the Mould and necessary Cores.4. Melt the metal/alloy to be cast.5. Pour the molten metal/alloy into mould and remove the

casting from the mould after the metal solidifies.6. Clean and finish the casting.7. Test and inspect the casting.8. Remove the defects, if any.9. Relieve the casting stresses by Heat Treatment.10. Again inspect the casting.11. The casting is ready for shipping.

• These cast steels are then classified into unalloyed cast steels (cast carbon steels) and alloyed cast steels with either low or high amount of alloying elements

• There is also special alloys steel which has different designation from those steels described before.

Designation for unalloyed and low alloyed cast steels(DIN Standard)

• These steels are designated as “GS”• Example : GS-17 CrMo 5.5, this designation means:

- The type of steel is cast steel which contains a low or small amount of alloying elements.- The carbon content of this steel is 0,17%- The Chromium content is 1,25%- The Molybdenum content is 0,5%

• The addition of letter X to GS is typical designation for high alloyed cast steel.

• Example : GS-X5 CrNiMo 18 12 means :- cast steel with high amount addition of alloying elements- The carbon content of the steel is 0,05%- The Chromium content is 18%- The Nickel content is 12%- Contains small amount of Molybdenum

Designation for high alloyed cast steels(DIN Standard)

• The special alloyed cast steels have their own rules of designation that alloying elements are arranged in a certain order start from W and then followed,Mo,V and Co.

• Example; S 10-4-3-10- S means high speed alloy steels /HSS (British)- 10 10% Wolfram- 4 4%Molybdenum- 3 3% Vanadium- 10 10% Cobalt

• These steels are generally used for cutting tools.

Designation for special alloyed cast steels(DIN Standard)

PLAIN CARBON STEELSCarbon steel, also called plain-carbon steel, is steel where the main interstitial alloying constituent is carbon. Others are presents less than 3%.

According to AISI :

Steel is considered to be carbon steel when the specified minimum for copper does not exceed 0.40 percent; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60.

I. Low Carbon Steel

• These steel contain less than 0,2%C.• These steel have a relatively low tensile strength,

but it is cheap and malleable, thus it is easy to beformed.

• It also have a good weldability characteristic• The largest category of this class of steel is flat-

rolled products (sheet or strip) usually in the cold-rolled and annealed condition

• Typical applications are in automobile bodypanels, tin plate, and wire products, deepdrawing parts, chain, pipe, wire, nails, somemachine parts

• These steel contain 0,2%C ~ 0,5%C• These steel have good toughness, ductility,

high tensile strength and wear resistant.• These steels are specified for application

requiring higher strength than the low Csteels.

• The application of medium carbon-manganesesteels include machinery components andengine parts such as shafts, couplings,crankshafts, axles, screw, and gears

II. Medium Carbon Steel

III. High Carbon steels

• These steels contain more than 0,5%C

• These steels have higher strength, hardness and wear resistance. Steels also have moderate ductility.

• The steels are often used for high strength, high hardness, stiffness and wear resistant application such as springs, cutting tools, blades, wrenches etc.

ALLOY STEELS

• Various elements are added into steel in order toimprove its mechanical properties as required by thecustomer. These elements are called alloying elements.

• Alloy steels are classified into two group :- Low alloy steels (the total amount of alloying elements

is less than 8%), example : AISI 4340, GS30Mn5- High alloy steels (the amount of one of the alloying

elements which are added into steel greater than 8%).Example: AISI 304

CORROSION RESISTANT STEELS

• Best known as “Stainless” steel.• These steels contain a high percentage of Cr which

reacts with oxygen result in a passive layer called chromium oxide.

• Such a layer protects the steel from corrotion.• Corrotion resistance steels have a minimum Cr content

of 10%.• But, various stainless steels types have limited

resistance to certain chemical such as chlorine and/or sulfur ion.

Type of Stainless Steels

• Austenitic stainless steel (AISI 2XX Cr-Ni-Mn ; AISI 3XX Cr-Ni).

• Ferritic stainless steel (AISI 4XX)• Martensitic stainless steel (AISI 4XX with lower C and

Mn to permit hardenability by heat treatment)• Duplex stainless steel• Precipitation hardened stainless steel

Type C Mn SI Cr Ni Mo

Austenitic (Chromium-Nickel) (Chromium-Manganese-Nickel)

201 0,15 5,5 -7,5 1 16 – 18 3,5 – 5,5

202 0,15 7,5 -10 1 17 – 19 4 – 6

301 0,15 2 1 16 – 18 6 – 8

302 0,15 2 0,75 17 – 19 8 – 10

304 0,08 2 0,75 18 – 20 8 – 10,5

310S 0,04 – 0,1 2 0,75 24 – 46 19 – 22

316 0,08 2 0,75 16 – 18 10 – 14 2 – 3

316L 0,03 2 0,75 16 - 18 10 - 14 2 - 3

Duplex ( Austenitic – Ferritic )

329 0,08 1 0,75 23 – 28 2,5 - 5 1 – 2

Ferritic or Martensitic ( Chromium)

410 0,15 1 1 11,5 – 13,5 0,75

440C 0,95 – 1,2 1 1 16 – 18 0,75

444 0,25 1 1 17,5 – 19,5 1 1,75 – 2,5

Austenitic Stainless Steels

• The series 2XX and 3XX contain more Mn than others stainless steel.

• They usually possess excellent cryogenic properties and good high-temperature strength and oxidation resistance

• They also have good ductility and formability• These steels are generally used in food processing

machinery, kitchen sink and jet engine parts• Example :

- AISI 304 is commonly applied for food and milk products, chemical equipment, kitchen equipments etc.

Ferritic Stainless Steels• Ferritic stainless steels are essentially iron-chromium

alloys. • The ferritic stainless steels are ferromagnetic.• Their ductility and formability is lower than austenitic

stainless steel, but they are more resistant to stress corrosion cracking.

• These steels can’t be hardened by heat treatment due to its lower carbon content

• The application include benchwork, cold-water tanks, refrigeration cabinets, chemical and food processing, water treatment plant, street furniture, electrical cabinets

Type 430

The basic ferritic grade, with a little less corrosion resistance thanType 304. This type combines high resistance to such corrosivesas nitric acid, sulfur gases, and many organic and food acids.

Type 405

Has lower chromium and added aluminum to prevent hardeningwhen cooled from high temperatures. Typical applications includeheat exchangers.

Type 409

Contains the lowest chromium content of all stainless steels and isalso the least expensive. Originally designed for muffler stock andalso used for exterior parts in non-critical corrosive environments.

Type 434

Has molybdenum added for improved corrosion resistance. Typicalapplications include automotive trim and fasteners.

Type 436

Type 436 has columbium added for corrosion and heat resistance.Typical applications include deep-drawn parts.

Type 442

Has increased chromium to improve scaling resistance. Typicalapplications include furnace and heater parts.

Type 446

Contains even more chromium added to further improve corrosionand scaling resistance at high temperatures. Especially good foroxidation resistance in sulfuric atmospheres.

Martensitic Stainless Steels• Martensitic stainless steels are essentially Fe-Cr-C

alloys. • They are ferromagnetic, hardenable by heat treating due

to its higher C and lower Cr and generally resistant to corrosion only in relatively mild environments

• They are considered the most difficult to weld.• The type of 410 1nd 414 martensitic stainless steels are

mostly used for knifes blade, springs, pump parts etc.

Duplex Stainless Steel

• The microstructure of duplex stainless steels consist of austenite and ferrite.

• These steels are highly resistant to Chloride stress corrosion cracking ( have excellent pitting and crevice corrosion resistance)

• PREN (Pitting Resistance Equivalent Number)PREN =%Cr + 3.3(%Mo) + 16(%N)

PREN < 32 low alloy duplex32 <PREN<39 intermediate gradePREN > 40 Superduplex

• Typical application : chemical and petrochemical industries, marine transportation, oil and gas industries.

HEAT RESISTANT STEELS

• Such steel is generally used in application whereresistance to increased temperatures is critical.

• It is used where the service temperatures exceed 650oCand may reach extremes as high as 1315oC

• Compare to corrosion resistant steels, these heatresistant steels have a higher carbon content.

• According to ACI designation system, these steelsinclude :- Ferritic ; HA and HC- duplex structure ; HD,HE,HF and HH- Fully austenitic ; HK, HX

TOOL STEELSWater-hardening tool steels W

Shock-resisting tool steels S

Cold work tool steels

Oil-hardening types O

Medium-alloy air-hardening types A

High-carbon-high chromium types D

Hot work tool steels

Chromium-base types H

Tungsten-base types H21

High speed tool steels

Tungsten-base types T

Molybdenum-base types M

Special purpose tool steels

Low alloy types L

Example : HSS Steels