Co related to chapter

1. Co related to chapter Select suitable steels/cast irons, non ferrous metals for particular applications as per properties. Visit for more Learning Resources

2. Unit 3: Ferrous metals and Designation What is steel? Steel is a interstitial solid solution of iron and carbon containing 0.008 to 2% carbon by weight

3. Classification of Steels Steels are classified base on various criterions: • Amount of carbon • Amount of alloying elements • Amount of deoxidation • Grain Coasening Characteristics • Method of Manufacturing • Depth of Hardening • Form and use

4. Classification of Steels • Amount of carbon • Low carbon steel (0.008 – 0.3 %C) • Medium carbon steel (0.3 – 0.6 %C) • High carbon steel (0.6 – 2 %C)

5. Classification of Steels • Amount of carbon • Low carbon steel • Soft • ductile • malleable • tough • machinable • weldable • non hardenable by heat treatment

6. Classification of Steels Applications of Low carbon steel • Good for cold working such as rolling into thin sheets • Good for fabrication work by welding, pressing or machining • Used for wire, nails, rivets, screws, panels, welding rod, ship plates, boiler plates, tubes for bicycles and automobiles • Steels with o.15 to 0.3 %C are widely used as Structural steels and used for building bars, grills, beams, angles, channels etc. • Mild Steel is well known from this group

7. Classification of Steels Medium carbon steel • Medium Soft • Mediumductile • Mediummalleable • Mediumtough • Depth of hardening is less • Slightly difficult to machine, weld and harden • Difficult to cold work • They are also called as machinery steels

8. Classification of Steels Applications of medium carbon steel Used for • Bolts • Axles • Lock washer • Forging dies • Springs • Wheel Spokes • Railway rails

9. Classification of Steels High carbon steel • Hard • Wear Resistant • Brittle • Difficult to cold work • Very difficult to machine and weld • Depth of hardening is more • They are also called as Tool Steels

10. Classification of Steels Applications of high carbon steel Used for • Dies • Punches • Hammers • Chisels • Drills • Metal cutting saws • Razor blades

11. Classification of Steels • On the basis of alloying elements • Low alloy steels (Total alloying elements are less than 10%) • High alloy steels (Total alloying elements are more than 10%)

12. Classification of Steels • On the basis of alloying elements and carbon content • Low carbon Low alloy steels • Low carbon High alloy steels • Medium carbon Low alloy steels • Medium carbon High alloy steels • High carbon Low alloy steels • High carbon High alloy steels

13. Classification of Steels • On the basis of deoxidation • Rimmed steels • Killed steels • Semi-killed steels

14. Classification of Steels • On the basis of deoxidation • A molten steel contains large amount of dissolved oxygen and other gases. • The solubility of gases is more in the liquid metal than in the solid metal and hence the dissolved oxygen along with other gases tries to go out as CO during solidification and a large part of it gets entrapped into solidified ingot. • Rimmed steels • In rimmed steels no treatment is given to dissolved gases. • The tapped gases form blow holes which compensate for the usual liquid to solid shrinkage.

15. Classification of Steels • On the basis of deoxidation • Rimmed steels • The thin solidified layer of ingot i.e. rim (skin) formed at surface which contains low carbon, less impurities and no blow holes • These steels coarsen rapidly during heating in austenitic region. • Generally low carbon steels containing less than 0.15% carbon are produced in sheet form in rimmed condition and used for deep drawing and forming operations.

16. Classification of Steels • On the basis of deoxidation • Rimmed steels

17. Classification of Steels • On the basis of deoxidation • Killed steels • The dissolved oxygen from the melt is completely removed by addition of strong deoxidising agents like Al, Si, Mn and V. • The deoxidisers are added to the steel in the furnace prior to pouring into mould. • They rapidly combine with the dissolved oxygen and form respective oxides thus reduces dissolve oxygen. • Killed steel shows more shrinkage (called as pipe) during solidification due to absence of blow holes.

18. Classification of Steels • On the basis of deoxidation • Killed steels

19. Classification of Steels • On the basis of deoxidation • Killed steels • Killed steels shows fined grain characteristics since oxide inclusions which inhibits the grain boundary migration • Killed steel ingot has sound , defect free, less segregated structure throughout the cross section • Usually high carbon steels and alloy steels are produced in the killed condition.

20. Classification of Steels • On the basis of deoxidation • Semi-killed steels • In these steels part of the dissolved oxygen is removed by addition of deoxidisers. • Blow holes formed compensate for part of the shrinkage and hence pipe is less. • They show intermediate grain coarsening characteristics. • Usually steels containing carbon between 0.15 to 0.25% are produced.

21. Classification of Steels • On the basis of Grain Coarsening characteristics During heating,100 % austenite is formed at just above the upper critical temperature and the grains are of smallest size. As the temperature increases above this, the grain size may increase. Depending on the grain coarsening characteristics, steels are classified into two types as : • Coarse grained steels • Fine grained steels

22. Classification of Steels • On the basis of Grain Coarsening characteristics • Coarse grained steels Coarse grained steels coarsen rapidly with temperature. • Fine grained steels These steels maintain a relatively fine and uniform grain size even after holding for long time at high temperature. Fine grained steels do not coarsen up to a definite temperature. Above this temperature, they coarsen very fast and may reach a size greater than those of coarse grained steels.

23. Classification of Steels • On the basis of Grain Coarsening characteristics Coarse Grained Steels Austenitic Grain Size Fined Grained Steels 700 800 900 1000 1100 1200 Temperature

24. Classification of Steels • On the basis of Grain Coarsening characteristics • Usually rimmed steels behave coarse grained steels. • Killed steels and alloy steels behave fine grained steels. • The oxide inclusions in killed steels and undissolved alloy carbides in alloy steels inhibit the grain boundary migration, thus reducing grain coarsening. • In the absence of such particles, grain coarsening is rapid.

25. Classification of Steels • On the basis of Method of Manufacuring • Basic open hearth • Acid open hearth • Acid Bessemer • Basic oxygen process • Electrical Furnace

26. Classification of Steels • On the basis of Depth of Hardening • Non-hardenable Can’t be hardened by quenching • Shallow hardening steels hardened by quenching up to a small depth • Deep hardening steels hardened by quenching deeply

27. Classification of Steels • On the basis of Depth of Hardening • Non-hardenable Very low hardenablilty Low carbon steels with no alloying elements • Shallow hardening steels Medium hardenability Medium carbon steels with low alloying elements • Deep hardening steels High hardenability High carbon steels with high alloying elements

28. Classification of Steels • On the basis of form and use Based on form: • Cast steels • Wrought steels • Based on Use: Boiler steels Case hardening steels Corrosion and heat resistant steels Deep drawing steels Electrical steels Free Cutting steels Machinery steels Structural steels Tool steels

29. ALLOY STEEL • alloy steel are the steels containing other elements like ni,mn,cr,w,mo,v etc. which are added to plain steels for enhancement of their one or more properties. • addition of such elements leads to…… • more strength ,hardness and toughness at low and high temp. • better resistance to wear and abrasion due to the presence of allloy carbides. • high hardenability • less tendency to warping and cracking during heat treatments. • more uniform properties throughout the cross-seection • less tendacy to decarburization

30. 7) high corrosion and oxidation resistance efeect of alloying elements 1)solid solution strengthening/hardening: most of the alloying elements are soluble in ferrite to some extent and form solid solution when added to steel. solid solution are harder and stronger than pure metal and hence these elements increases the strength ad hardness of steel. example: mn, cr, w, mo, v, ti, si, al,zr,p,…. elements like p, si,mn and more effective as solid soltion strengtheners.

31. 2) formation of carbides: some of the alloying elements combine with carbon in the steel and form respective carbides. these alloy carbides are hard and increases wear and abrasion resistance of steel. chromium and vanadium carbides have maximum hardness and formation of these carbides during tempering of high alloy tool steel. example: ti,zr,v, nb,w, mo,cr,mn 3) formation of inclusions: they may combine with oxygen and form oxides when added to steel. example: si, al, mn, cr, v, ti,….. 4)shifting of critical temp and eutectoid carbon: the alloying element may lower or raise thr transformation temp. of steel.

32. elements which are austenite stabilizer like ni and mn lower the eutectoid temp (a1) , while the elements which are ferrite stabilizers raise the above temp. ti and mo are amongest the effective elements in the raising the eutectoid temp.

33. 5)LOWERING CRITICAL COOLOING RATE: MOST OF ALLOYING ELEMENTS (EXCEPT CO) SHIFT THE I.T. DIAGRAM TO THE RIGHT SIDE, THUS DECREASING THE CRITICAL COOLING RATE . THIS EFFECT IS VERY USEFUL FOR INCRESING THE HARDENABILITY OF STEEL. ELEMENTS SUCH AS Mn, Mo, Cr AND Ni ARE MORE EFFECTIVE IN INCREASING THE HARDENABILITY.

34. 6) CHANGE IN VOLUME DURING TRANSFORMATION: THE VOLUME CHANGE RESULTING FROM AUSTENITE TO MARTENSITE. 7) OTHER EFFECT: CORROSION AND OXIDATION RESISTANCE MAY INCREASES CREEP STRENGTH MAY INCREASED FATIGUE STREGTH MAY ALSO GET INCREASED.

35. PROPERTIES AND USES OF ALLOYING ELEMENT: 1)SULPHAR SULPHAR COMBINES WITH IRON AND FORMS IRON SULPHIDE WHICH IS A HARD AND BRITTLE PHASE. IT HAS LOW MELTING POINT DURING HOT WORKING OF STEEL, THIS PHASE LIQUIFIES AT THE TEMP. OF WORKING AND STEEL BECOMES HOT SHORT. THESE PROBLEMS ARE REDUCED BY RESTRICTING THE AMOUNT OF SULPHAR TO A MAXIMUM OF 0.05% AND ADDITION OF MANGANESE. IN PRESENCE OF MANGANESE MnS IS FORMED WHICH IS NOT SO HARD AND BRITTLE AS FeS. ALSO ITS MELTING POINT IS HIGHER THAN THAT OF FeS , DUE TO THIS MANGANESE ADDITION REDUCES BRITTLENESS AND HOT SHORTNESS. IT ALSO INCREASES MACHINABILITY.

36. PROPERTIES AND USES OF ALLOYING ELEMENT: 2) PHOSPHORUS PHOSPHOROUS DISSOLVES IN FERRITE PHASE AND INCREASES ITS TENSILE STRENGTH AND HARDNESS. IT IS MOST POWERFUL SOLID SOLUTION STRENGHTER. ADDITON OF PHOSPOROUS IN LARGE AMOUNT INCREASES THE BRITTLENESS IT ALSO INCREASES MACHINABILITY. 3)SILICON IT DISSOLVES IN FERRITE ,INCREASES STRENGTH,HARDNESS,TOUGHNESS WIYHOUT LOSS OF DUCTILITY. SILICON IS ADDED UP TO 5% TO PRODUCE MAGNETICALLY SOFT MATERIALS FOR TRANSFORMERS,MOTTORS AND GENERATOR LAMINATION. SILICON IS PURPOSELY ADDED IN THE SPRING STEELS,CHISELS, PUNCHES AND AUTOMOBILE VALVES TO INCREASE THEIR TOUGHNESS. SILICON IS ADDDED UP TO 0.2% IN TOOL STEEL ,MORE THAN THIS % IT TEND TO DECOMPOSE CARBIDE IN TO GRAPHITE. 4)MANGANESE IT DISSOLVE IN FERRITE AND INCREASES YIELD STRENGTH ,TENSILE STRENGTH, TOUGHNESS AND HARDNESS.

37. PROPERTIES AND USES OF ALLOYING ELEMENTS SINCE IT IS LESS EXPENSIVE ELEMENTS,IT IS GENERALLY ADDED TO ALL STRUCTURAL STEELS FOR STRENGTHENING PURPOSE. HIGHER AMOUNT OF MANGANESE(12-14%) IS ADDED TO STEEL WITH 1 TO 2 % CARBON TO PRODUCE AN EXTREMELY TOUGH WEAR RESISTANT AND NON MAGNETIC FIELD CALLED HADFIELD STEEL. (MnS)IT INCREASES MACHINABILITY OF STEEL AND HENSE FREE CUTTING OR FREE MACHINING STEEL CONTAIN Mn UP TO A MAXIMIUM OF 1.6% ALONG WITH INCREASED AMOUNT OF SULPHAR. 5)NICKEL IT DISSOLVES IN FERRITE AND INCRESES HARDNESS,TENSILE STRENGTH AND TOUGHNESS WITHOUT DECREASING DUCTILITY. UP TO 5% Ni IS ADDED TO STEELS REQUIRING HIGH TENSILE STRENGTH AND TOUGHNESS. HIGH ADDITION OF Ni MAKES THE STEEL AUSTENITIC AT ROOM TEMP. SUCH STEELS ARE SOFT ,DUCTILE ,MALLEABLE AND NON MAGNETIC. NICKEL ALSO INCREASES CORROSION RESISTANCE AND OXIDATION RESISTANCE IF ADDED IN EXCESS OF 5%. IT FOUND APPLICATION IN LOCOMOTIVE BOILERS,BOLTS,RAILWAY AXLE AND BRIDGE STUCTURE.

38. PROPERTIES AND USES OF ALLOYING ELEMENTS 6) CHROMIUM IT INCREASES HARDENABILITY OF STEEL TO A GREATER EXTENT . IT FORMS CARBIDES AND INCREASES HARDNESS AND WEAR RESISTANCE OF STEEL. IT INCREASES CORROSION AND OXIDATION RESISTANCE WHEN ADDED IN SUBSTANTIAL AMOUNT. IT INCREASES SERVICE LIFE AND PERFOMANCE OF SUCH STEEL AS CUTTING TOOLS,DIES,BALL BEARING. 7)TUNGUSTEN IT INCREASES HARDENABILITY IT FORMS CARBIDES AND INCREASES WEAR AND ABRASION RESISTANCE. IT REDUCES THE TENDANCY OF DECARBURIZATION. IT REFINE THE GRAIN SIZE. 8)MOLYBDENUM SAME AS THAT OF TUNGUSTEN

39. PROPERTIES AND USE OF ALLOYING ELEMENT. 9)VANADIUM IT INCREASES FATIGUE AND CREEP RESISTANCE. THE RESISTANCE TO GRAIN COARSENING IS EXCELLENT. EXCELLENT WEAR RESISTANCE. 10)COBALT IT REDUCES HARDENABILITY OF STEEL. IT IS AN IMPORTANT ALLOYING ADDITION IN PERMANENT MAGNETS, HIGH TEMP. SERVICE MATERIAL. 11) ALLUMINIUM IT IS A GRAIN REFINER 12)BORON SMALL ADDITION OF BORON (0.001-0.003%)SHARPLY INCREASES HARDENABILITY OF MEDIUM CARBON STEEL. HIGH SURFACE HARDNESS,WEAR RESISTANCE,CORROSION RESISTANCE. BORON DIFFUSED SURFACES OF HOT FORGING DIES CONSIDERABLY INCREASES THEIR SERVICE LIFE. IT IMPROOVER MACHINABILITY OF STEEL.

40. TOOL STEELS THESE STEELS ARE SPECIALLY USED FOR WORKING,SHAPING AND CUTTING OF METALS. 1)COLD WORK TOOL STEEL 2)HOT WORK TOOL STEEL 3)HIGH SPEED TOOL STEEL 4)SPECIAL PURPOSE TOOL STEEL. ALL TOOL STEEL SHOULD BE HARD,TOUGH AND WEAR RESISTANT. 1)COLD WORK TOOL STEEL THESE TOOL STEELS ARE USED FOR COLD WORKING OF METALS. THEY HAVE GOOD HARDNESS AND WEAR RESISTANCE AT LOW TEMP. SOME OF THE STEELS FROM THIS GROUP CONTAIN VERY LITTLE OR NO ALLOYING ELEMENTS AND HENSE ARE LESS EXPENSIVE. DEPENDING UPON THEIR HARDENING CHARACTERISTICS THEY ARE CLASSIFIED IN TO SUBGROUPS SUCH AS WATER HARDENING STEELS (W-SERIES), OIL HARDENING STEELS (O-SERIES), AIR HARDENING STEEL (A-SERIES) AND HIGH CARBON HIGH CHROMIUM STEELS.(D-SERIES)

41. HOT WORK TOOL STEELS THESE STEELS ARE MAINLY USED FOR HOT WORKING OF METALS SUCH AS DRAWING,PIERCING,EXTRUDING ETC. THEY HAVE GOOD STRENGTH,TOUGHNESS, HARDNESS AND WEAR RESISTANCE. THEY HAVE EXCELLENT RESISTANCE TO TEMPERING/SOFTENING . THEY HAVE LOW TO HIGH ALLOY CONTENT WITH RELATIVELY LESS CARBON (0.35 TO 0.65%)AND ARE CLASSIFIED IN TO THREE TYPES DEPENDING UPON THE PRINCIPAL ALLOYING ELEMENT. THESE ARE CHROMIUM TYPE, TUNGUSTEN TYPE,AND MOLYBDENUM TYPE. HIGH SPEED TOOL STEEL THESE STEELS MAINTAIN HIGH HARDNESS UP TO A TEMP OF ABOUT 550 C AND HENCE CAN BE USED FOR CUTTING OF METALS AT HIGH SPEEDS. THEY ALSO HAVE HIGH WEAR RESISTANCE AND CUTTING ABILITY. HIGH SPEED STEELS ARE CLASSIFIED IN TO TWO TYPES…….. 1)TUNGUSTEN HIGH SPEED: IT CONTAIN HIGH AMOUNT OF W WITH OTHER ELEMENT SUCH AS Cr, V, AND Co. THEY ARE DESIGNATED BY T-SERIES.

42. THE MOST WIDELY USED GRADE IS T1 WHICH CONTAIN 0.7%C,18 %W, 4%Cr AND 1%V . 2)MOLYBDENUM STEELS : A PART OF TUNGUSTEN FROM THE GROUP OF W-HIGH SPEED STEELS IS SUBSTITUTED BY MOLYBDENUM AND HENSE THESE STEEL CONTAIN W,CR,V AND CO IN THE ADDITION TO MO. THIS SUBSTITUTION RESULTS IN LOWERING THE COST OF STEEL. EVEN THOUGH MOLYBDENUM STEELS ARE CHEPER,THEY ARE DIFFICULT TO HEAT TREAT BECAUSE OF MORE TENDENCY OF OXIDATION DECARBURIZATION AND GRAIN GROWTH DURING HEAT TREATMENTS AS COMPARED TO W-TYPE HIGH SPEED STEELS. THIS TYPE IS DESIGNATED BY M-SERIES. THE MOST WIDELY USED GRADE IS M2 WHICH CONTAIN 0.85%C, 6%W, 5%MO, 4%Cr, AND 2%V. APPLICATION: DRILLS ,LATHE TOOLS , PUNCHES, DRAWING DIES, AND WOOD WORKING TOOS. TAPS REAMERS ,MILLING CUTTERS, SAW.

43. HIGH CARBON HIGH CHROMIUM STEEL(HCHC) THEY HAVE HIGH HARDENABILITY AND HENSE CAN BE HARDENED BY OIL OR AIR QUENCHING. THEIR DISTORTION DURING HARDENING IS LESS. THEY CONTAIN CARBON ABOVE 1.5% AND SOME OF GRADES CONTAIN CARBON EVEN MORE THAN 2% WITH CHROMIUM ABOUT 12 % AND OTHER ELEMENT SUCH AS W,MO, V IN SMALL AMOUNT. DUE TO THIS ,THE AMOUNT OF COMPLEX ALLOY CARBIDE IS MORE WHICH INCREASES HARDNESS AND WEAR RESISTANCE OF THESE STEELS,BUT THEY DIFFICULT TO MACHINE. THEY ARE USED FOR DRAWING DIES, BLANKING DIES, FORMING DIES, COINING DIES, THREAD ROLLING DIES. TRIMMING DIES, BUSHINGS, SHEAR BLADES, PUNCHES, COLD FORMING ROLLS,CUTTING TOOLS,GUAGES ETC. THEY MAINTAIN SUFFICINT HARDNESS UP TO 500 C DUE TO PRESENCE OF ALLOY CARBIDES.

44. OIL HARDNED NON SHRINKAGE STEEL(OHNS) THESE STEEL CONTAIN SMALL AMOUNT OF ALLOYING ELEMENTS SUCH AS W, Mn, Cr, Mo AND V. DUE TO THIS ,THEIR HARDENABILITY IS BETTER THAN THE WATER HARDENING TOOL STEELS AND THEREFORE ,THEY CAN BE HARDENED BY OIL QUENCHING. THEY ARE NOT EXPENSIVE AS OTHER TOOL STEEL AND ARE USED FOR BLANKING AND FORMING DIES,SHEAR BLADE, MASTER TOOLS, CUTTING TOOLS AND GUAGES. THE DISTORTION DURING HARDENING IS LESS AND HENSE THEY ARE CALLED AS OIL HARDENING NON-SHRINKAGE (OHNS) STEELS. A CHEAPEST NON SHRINKAGE STEEL (O2) CONTAIN 0.9%C AND 1.6%Mn . A BETTER STEEL CONTAINS 1% C, 0.95% Mn, 0.5%W, 0.75% Cr AND 0.2%V.

45. STAINLESS STEEL: THESE STEEL HAVE HIGH CORROSION RESISTANCE AND HENSE THEY DO NOT CORRODE IN MOST OF THE THE USUAL ENVIRONMENTAL CONDITIONS. THE HIGH CORROSION RESISTANCE IS DUE TO THE PRESENCE OF CHROMIUM IN THESE STEEL. FOR SUFFICIENT CORROSION RESISTANCE TO HAVE STAINLESS PROPERTY IN THE MOST GENERAL TYPE ENVIRONMENTAL CONDITIONS, THE MINIUM AMOUNT OF CHROMIUM IN THE SOLID SOLUTION FORM SHOULD BE GRETER THAN 13%. AMOUNT OF CHROMIUM COMBINING WITH CARBON IS 17 TIMES THE AMOUNT OF CARBON. HIGHER THE CHROMIUM IN THE SOLID SOLUTION FORM AND LESSER THE AMOUNT OF CARBIDES, MANY OTHER ELEMENTS SUCH AS Ni, Mn,Mo,Ti,Cb, Ta, ETC. ARE ADDED TO IMPROVE CERTAIN PROPERTIES VARIOUS TYPE OF STAINLESS STEEL HAVE ONE OR MORE OF THE FOLLOWING PROPERTIES IN ADDITION TO THEIR HIGH CORROSION RESISTANCE. HIGH DUCTILITY HIGH RESISTANCE TO OXIDATION GOOD WELDABILITY

46. STAINLESS STEEL: GOOD CREEP RESISTANCE EXCELLENT SURFACE FINISH AND APPEARANCE. CLASSIFICATION OF STAINLESS STEEL 1)GROUP A CHROMIUM IS LESS THAN 13% HARD, WEAR RESISTANCE, MAGNETIC APPLICATION: SPRING,BALL BEARINGS,VALVES,RAZORS AND RAZOR BLADES,SURGICAL INSRUMENT, CUTTING TOOLS, CUTLERY ITEMS. 2)GROUP B CHROMIUM IS MORE THAN 13% OXIDATION RESISTANCE,SOFT,DUCTILE,MALLEABLE,MAGNETIC. APPLICATION:VESSEL IN CHEMICAL AND FOOD INDUSTRIES, PRESSURE VESSELS,FURNACE PART, HEATERS, HEAT EXCHANGERS, JUCE CARRYING PIPES IN SUGAR INDUSTRIES, ARCHITECTURAL AND AUTOMOTIVE TRIM, RESTAURANT EQUIPMENT , POTS AND PANS.

47. GROUP C THIS GROUP INCLUDE THOSE ALLOY WHICH CONTAIN AT LEAST 24% OF THE TOTAL OF Cr, Ni AND Mn. THE AMOUNT OF Cr IN THESE ALLOYS IS AT LEAST 18% WITH CARBON CONTENT BETWEEN 0.03 AND 0.25% SOFT ,DUCTILE, MALLEABLE, NON MAGNETIC,LOW THERMAL CONDUCTIVITY. APPLICATION:ENGINE MANIFOLDS,FOOD AND CHEMICAL PLANTS, TUBULAR EXCHANGERS,UTENSILS,WRIST WATCHES, SANITARI FITTINGS ETC.

48. CAST IRON CAST IRON BASICALLY THE ALLOYS OF IRON AND CARBON IN WHICH THE CARBON VARIES BETWEEN 2 TO 6.67% I.E. MORE THAN THE SOLUBILITY LIMIT OF CARBON IN AUSTENITE REGION AND LESS THAN THE CARBON CONTENT OF CEMENTITE.

49. CAST IRON COMMERCIAL CAST IRON ARE COMPLEX IN COMPOSITION AND CONTAIN CARBON IN THE RANGE OF 2.3 TO 3.75 % WITH OTHER ELEMENTS SUCH AS SILICON ,PHOSHORUS, SULPHAR AND MANGANESE IN SUBSTANSTIAL AMOUNT. BECAUSE OF THEIR POOR DUCTILITY AND MALLEABILITY, THEY CAN NOT BE FORGED, ROLLED, DRAWN OR PRESSED IN TO THE DESIRED SHAPE; BUT ARE FORMED BY MELTING AND CASTING WITH OR WITHOUT MACHINING TO THE REQUIRED FINAL SHAPE AND SIZE AND HENCE THE NAME “CAST IRON”. THEY ARE CHEAPEST AMONGEST THE COMMERCIAL ALLOYS. THEY AARE EASIER TO MELT BECAUSE OF THEIR LOWER MELTING TEMP. THEY HAVE EXCELLENT CASTABILITY THEIR CORROSION RESISTANCE IS FAIRLY GOOD. THEY ARE BRITTLE HIGH HARDNESS TO WEAR AND ABRASION EXCELLENT MACINABILITY.

50. CLASIFICATION OF CAST IRON ON THE BASIS OF FURNACE USED IN THEIR MANFACTURER 1)CUPOLA CAST IRON 2)AIR FURNACE CAST IRON 3)ELECTRIC FURNACE CAST IRON 4)DUPLEX CAST IRON ON THE BASIS OF COMPOSITION AND PURITY 1)LOW CARBON,LOW SILICON CAST IRONS 2)HIGH CARBON, LOW SULPHAR CAST IRONS 3)NICKEL ALLOY CAST IRON ETC ON THE BASIS OF MICROSTRUCTURE AND APPEARANCE OF FRACTURE 1)WHITE CAST IRON 2)MALLEABLE CAST IRON 3)GREY CAST IRON 4)NODULAR CAST IRON 5)MOLTED CAST IRON 6)CHILLED CAST IRON 7)ALLOY CAST IRON