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STEEL & ALLOY STEEL STEEL- %C TO 2.0 % AS PER I-C DIAG.

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Presentation on theme: "STEEL & ALLOY STEEL STEEL- %C TO 2.0 % AS PER I-C DIAG."— Presentation transcript:

1 STEEL & ALLOY STEEL STEEL- %C 0.008 TO 2.0 % AS PER I-C DIAG.
ALLOY STEEL – ALLOYING ELEMENTS ADDED Cr, Ni, Ti, W, V, Mo ETC.

2 PIG IRON IN MOLTEN OR SOLID STATE
FLOW DIAGRAM FOR STEEL PIG IRON IN MOLTEN OR SOLID STATE BESSEMER PROCESS OPEN HEARTH PROCESS L.D. PROCESS ELECTRIC PROCESS LINZ & DONAWITZ PROCESS INDUCTION FURNACE STEELS

3 SYLLABUS: STEEL: BROAD CLASSIFICATION OF STEEL, PLAIN CARBON STEEL
DEFINITION , TYPES & PROPERTIES COMPOSITIONS AND APPLICATIONS OF LOW, MEDIUM AND HIGH CARBON STEELS. ALLOY STEEL: DEFINITION AND EFFECTS OF ALLOYING ELEMENTS ON PROPERTIES OF ALLOY STEELS.

4 STEEL: OR PLAIN CARBON STEEL
IT IS AN ALLOY OF IRON AND CARBON. % C RANGE TO 2%. OTHER RESIDUAL ELEMENTS SUCH AS Mn, Si, P, & S. BRODLY CLASSIFIED AS UNALLOYED STEEL OR PLAIN CARBON STEELS ALLOY STEELS

5 ROLE OF CARBON IN STEEL:
C HAS STRENGTHING AND HARDENING EFFECT. IT LOWERS DUCTILITY i.e. DECRESE IN ELONGATION & REDUCTION OF AREA. RISE IN % C CONTENT LOWERS MACHINABILITY AND WELDABILITY. THERMAL & ELECTRICAL CONDUCTIVITY DECLINES. MAGNETIC PERMEABILITY DECRESES DRASTICALLY. LOWERS CORROSION RESISTANCE.

6 CLASSIFICATION OF STEEL ACCORDING TO DEOXYDATION PRACTICE.
1. KILLED STEEL 2. SEMI KILLED 3. RIMMEED STEEL KILLED STEEL: STRONGLY DEOXYDIZED AND CHARACTERISED BY HIGH COMPOSITION AND PROPERTY UNIFORMITY. ALL FORGING STEELS AND STEELS CONTAINING 0.25 % C ARE KILLED. THESE ARE HAVING FREEDOM FROM BLOW HOLES AND SEGREGATION. THERE IS NO EVOLUTION OF GAS AND THE TOP SURFACE OF THE INGOT SOLIDIFIES ALMOST IMMEDIATELY.

7 SEMI KILLED STEEL: RIMMED STEEL:
STRUCTURAL STEELS CONTAIMIMG 0.25 % C ARE GENERALLY SEMI KILLED. THE SURFACE HAS A SOUND SKIN OF COSIDERABLE THICKNESS. PLATES AND STRUCTURAL PRODUCTS ARE NORMALLY MADE OF SEMI KILLED STEELS. RIMMED STEEL: THE STEEL IS PARTIALLY DEOXYDIZED. A WIDE VARIATY OF STEELS FOR DEEP DRAWING IS MADE BY RIMMING PROCESS. i.e. EASE OF FORMING AND SURFACE FINISH ARE MAJOR CONSIDARATIONS. IDEAL FOR ROLLING. SHEETS AND STRIPS MADE FROM RIMMED STEEL HAVE EXCELLENT SURFACE QUALITY & COLD FORMING CHARACTERISTICS.

8 FREE CUTTING STEEL: HAVE HIGHER SULPHUR, PHOSPHROUS & LEAD. SULPHUR EXISTS IN THE FORM OF MnS ( MANGNESE SULPHIDE) , WHICH FORMS INCLUSIONS STRETCHED IN THE DIRECTION OF ROLLING. THESE INCLUSIONS PROMOTE THE FORMATION OF SHORT BRITTLE CHIPS AND REDUCE THE FRICTION BETWEEN THE SURFACE BEING MACHINED. GIVES GOOD SURFACE FINISH AT HIGHER CUTTING SPEEDS. P DISSOLVES IN THE FERRITE ( PURE IRON) INCRESES ITS BRITTLENESS.

9 HAVE LOWER DYNAMIC STRENGTH AND MORE SUSCEPTIBLE TO CORROSION.
FREE CUTTING STEEL… 0.15 – 0.35 % P CONSIDERABLY IMPROVES THE MACHINABILITY, WITHOUT REDUCING PHISICAL AND MECH. PROPERTIES TOOL LIFE INCREASED. THESE ARE SUPPLIED IN COLD DRAWN (WORK HARDENED) FORM. WHICH HAVE HIGH TS AND HARDNESS BUT LESS DUCTILE THAN ORDINARY C STEELS. LIMITATIOS- HAVE LOWER DYNAMIC STRENGTH AND MORE SUSCEPTIBLE TO CORROSION.

10 Carbon and Alloy Steels
All of these steels are alloys of Fe and C Plain carbon steels (less than 2% carbon and negligible amounts of other residual elements) Low Carbon (less than 0.3% carbon) Med Carbon (0.3% to 0.6%) High Carbon (0.6% to 0.95%) Low Alloy Steel High Alloy Steel Stainless Steels (Corrosion-Resistant Steels) – contain at least 10.5% Chromium Note, most steel alloys contain less than 1.0% carbon

11 Should be considered first in most application
Plain Carbon Steel Plain Carbon Steel Lowest cost Should be considered first in most application 3 Classifications AS PER C % Low Carbon (less than 0.3% carbon) Med Carbon (0.3% to 0.6%) High Carbon (0.6% to 0.95%) Plain Carbon Steel Lowest cost Should be considered first in most application 3 Classifications Low Carbon Steel Less than 0.20% Carbon Good formability and weldability Lacks hardenability (Difficult to harden) Medium Carbon Steel 0.20% to 0.50% Carbon Good toughness and ductility Poor Hardenability (typically limited to water quench) High Carbon Steel Greater than 0.50% carbon Low formability High hardness and wear resistance Poor hardenability (quench cracking occurs)

12 Plain Carbon Steel Again, alloy of iron and carbon with carbon the major strengthening element via solid solution strengthening. If carbon level high enough (greater than 0.6%) can be quench hardened (aka: dispersion hardening, through hardened, heat treated, austenized and quenched, etc..). Can come in HRS and CRS options HRS – HOT ROLLED STEEL CRS- COLD ROLLED STEEL The most common CRS are 1006 through 1050 and 1112, 1117 and other free machining steels Plain Carbon Steel Lowest cost Should be considered first in most application 3 Classifications Low Carbon Steel Less than 0.20% Carbon Good formability and weldability Lacks hardenability (Difficult to harden) Medium Carbon Steel 0.20% to 0.50% Carbon Good toughness and ductility Poor Hardenability (typically limited to water quench) High Carbon Steel Greater than 0.50% carbon Low formability High hardness and wear resistance Poor hardenability (quench cracking occurs)

13 Low Carbon (less than 0.3% carbon)
Plain Carbon Steel Low Carbon (less than 0.3% carbon) 1. Low strength, good formability If wear is a potential problem, can be carburized (diffusion hardening) Most stampings made from these stee 2. Med Carbon (0.3% to 0.6%) Have moderate to high strength with fairly good ductility Can be used in most machine element 3. High Carbon (0.6% to 0.95%) Have high strength, lower elongation Can be quench hardened Used in applications where surface subject to abrasion – tools, knives, chisels, agri implements. *Note, some texts including CES state med carbon as .3% to .5%

14 LOW C STEEL: ( % C) PROP: SOFT, DUCTILE, MALLEABLE , TOUGH, MACHINABLE , WELDABLE NON HARDENABLE BY HEAT TREATMENT. GOOD FOR COLD WORK. CAN BE DRAWN INTO WIRES AND SHEETS APP: WIRES, NAILS, RIVETS,SCREWS, WELDING RODS, SHIP PLATES, TUBES, FAN BLADES, GEARS, VALVES, CAM SHAFTS ETC.

15 Mild steel products Low carbon steel wire Low carbon steel wire Low carbon steel bars

16 MEDIUM HARD, DUCTILE AND TOUGH.
MEDIUM C STEEL: ( % C 0.30 TO 0.60) PROP: MEDIUM HARD, DUCTILE AND TOUGH. SLIGHTLY DIFFICULT TO MACHINE AND WELD. DIFFICULT TO COLD WORK HENCE HOT WORKED. CAN BE HARDEN BY HEAT TREATMENT. APP: BOLTS, AXLES, LOCK WASHERS, LARGE FORGING DIES, SPRINGS, SPROKETS, HAMMER, RODS, CRANK PINS ETC.

17 Circular saw blade- medium to high c steel
Seamless tube – medium c steel

18 HARD, WEAR RESISTANT, BRITTLE AND DIFFICULT TO MACHINE AND WELD.
HIGH C STEEL: %C PROP: HARD, WEAR RESISTANT, BRITTLE AND DIFFICULT TO MACHINE AND WELD. CAN BE HARDENED BY HEAT TREATMENT. CAN NOT COLD WORK AND HENCE HOT WORKED. APP: FORGING DIES, PUNCHES, HAMMERS, SPRINGS, CLUTCH DISCS, CAR BUMPERS, CHISELS, VICE JAWS, SHEAR BLADES, DRILLS, LEAF SPRINGS, KNIVES, RAZOR BLADES, BALLS AND RACES OF BALL BEARINGS, MANDRELS , CUTTERS, FILES, REAMERS, WIRE DRAWING DIES, METAL CUTTING SAWS.

19 Hunting knife- high c steel
Neck Knife – High Carbon Steel Hunting knife- high c steel Wire rope – high carbon steel

20 HRS vs. CRS HRS ingots or continuous cast shapes rolled in the “HOT” condition to a smaller shape. Since hot, grains recrystallize without material getting harder! HRS Characterized by: Extremely ductile (i.e. % elongation 20 to 30%) Moderate Rough surface finish – black scale left on surface.

21 HRS vs. CRS CRS CRS Characterized by:
coil of HRS rolled through a series of rolling mills AT ROOM TEMPERATURE. Since rolled at room temperature, get crystal defects called dislocations which impede motion via slip! Work hardening Limit to how much you can work harden before too brittle. How reverse? Can recrystallize by annealing. CRS Characterized by: Less ductlie – almost brittle (i.e. % elongation 5 to 10%) High strength

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24 Alloy Steel IT IS ADDITION OF TWO OR MORE ELEMENTS.
Other elements (besides carbon) can be added to iron to improve mechanical property, manufacturing, or environmental property. Elements such as Cr, Ni, W, V, Mo, Ti, Co, Mn, etc. Example: sulfur, phosphorous, or lead can be added to improve machine ability. Generally want to use for screw machine parts or parts with high production rates! Note,

25 Alloy Steel Again, elements added to steel can dissolve in iron (solid solution strengthening): Increase strength, hardenability, toughness, creep, high temp resistance. Alloy steels grouped into low, med and high-alloy steels. High-alloy steels would be the stainless steel groups. Most alloy steels you’ll use fall under the category of low alloy. Note,

26 Alloy Steel Most common alloy elements:
> 1.65%Mn, > 0.60% Si, or >0.60% Cu Most common alloy elements: Chromium, nickel, molybdenum, vanadium, tungsten, cobalt, boron, and copper. Low alloy: Added in small percents (<5%) increase strength and hardenability High alloy: Added in large percents (>20%) i.e. > 10.5% Cr = stainless steel where Cr improves corrosion resistance and stability at high or low temps Alloy Steel What classifies a steel as an Alloy Steel > 1.65%Mn, > 0.60% Si, or >0.60% Cu Definite or minimum amount of an alloying element is specified Most alloying elements added to steel are < 5% to increase strength and hardenability Most alloying elements added to steel are > 20% to improve corrosion resistance or stability at high or low temps

27 Alloying Elements used in Steel
Manganese (Mn) combines with sulfur to prevent brittleness >1% increases hardenability 11% to 14% increases hardness good ductility high strain hardening capacity excellent wear resistance Ideal for impact resisting tools Manganese (Mn) combines with sulfur to prevent brittleness >1% increases hardenability 11% to 14% increases hardness good ductility high strain hardening capacity excellent wear resistance Ideal for impact resisting tools Sulfur (S) usually not desired in steel because it will impart brittleness, but okay if combined with Mn Some free-machining steels contain 0.08 to 0.15% S

28 Alloying Elements used in Steel
Sulfur (S) Imparts brittleness Improves machineability Okay if combined with Mn Some free-machining steels contain 0.08% to 0.15% S Examples of S alloys: 11xx – sulfurized (free-cutting) Sulfur (S) usually not desired in steel because it will impart brittleness, but okay if combined with Mn Some free-machining steels contain 0.08 to 0.15% S

29 Alloying Elements used in Steel
Nickel (Ni) Provides strength, stability and toughness, Examples of Ni alloys: 30xx – Nickel (0.70%), chromium (0.70%) 31xx – Nickel (1.25%), chromium (0.60%) 32xx – Nickel (1.75%), chromium (1.00%) 33XX – Nickel (3.50%), chromium (1.50%) Nickel (Ni) added to steel to increase toughness and impact resistance 2% to 5% typically used in combination with Chromium and Molybdenum 12% to 20% Nickel AND low amounts of Carbon possess great corrosion resistance Invar contains 36% Ni virtually no thermal expansion used for sensitive measuring devices

30 Alloying Elements used in Steel
Chromium (Cr) Usually < 2% increase hardenability and strength Offers corrosion resistance by forming stable oxide surface typically used in combination with Ni and Mo Molybdenum (Mo) Usually < 0.3% Mo-carbides help increase creep resistance at elevated temps typical application is hot working tools Chromium (Cr) Usually less than 2% used primarily to increase hardenability and strength typically used in combination with Ni and Mo chromium carbides can enhance wear resistance Molybdenum (Mo) Usually less than 0.3% used to increase hardenability and strength Mo-carbides help increase creep resistance at elevated temps typical application is hot working tools

31 Alloying Elements used in Steel
Vanadium (V) Usually 0.03% to 0.25% increase strength without loss of ductility Tungsten (W) helps to form stable carbides increases hot hardness used in tool steels Vanadium (V) Usually 0.03% to 0.25% Va-carbides help to increase strength without loss of ductility elastic limit, yield point, and impact strength Tungsten (W) helps to form stable carbides increases hot hardness used in tool steels

32 Alloying Elements used in Steel
Copper (Cu) 0.10% to 0.50% increase corrosion resistance Reduced surface quality and hot-working ability used in low carbon sheet steel and structural steels Silicon (Si) About 2% increase strength without loss of ductility enhances magnetic properties Copper (Cu) 0.10% to 0.50% helps to increase corrosion resistance surface quality and hot-working ability decline used in low carbon sheet steel and structural steels Silicon (Si) about 2% helps to increase strength without loss of ductility used in structural steels and spring steels also helps to enhance magnetic properties

33 Alloying Elements used in Steel
Boron (B) for low carbon steels, can drastically increase hardenability improves machinablity and cold forming capacity Aluminum (Al) deoxidizer 0.95% to 1.30% produce Al-nitrides during nitriding Boron (B) for low carbon steels, B can drastically increase hardenability as the carbon content goes up the hardenabilty goes down improves machinablity and cold forming capacity Aluminum (Al) deoxidizer 0.95% to 1.30% produce Al-nitrides during nitriding

34 Selecting Steels High-Strength Low-Alloy Structural Steel
Microalloyed Steel Free-Machining Steel Bake-Hardenable Steel Sheet Precoated Steel Sheet Electrical and Magnetic Applications Maraging Steel High-Temperature Steel Stainless Steel Tool Steel In the book, Read up on each of these High-Strength Low-Alloy Structural Steel Microalloyed Steel Free-Machining Steel Bake-Hardenable Steel Sheet Precoated Steel Sheet Electrical and Magnetic Applications Maraging Steel High-Temperature Steel Important material with many applications Stainless Steel Tool Steel

35 Corrosion Resistant Steel
Stainless Steels (Corrosion-Resistant Steels) – contain at least 10.5% Chromium trade name AISI assigns a 3 digit number 200 and 300 … Austenitic Stainless Steel 400 … Ferritic or Martensitic Stainless Steel 500 … Martensitic Stainless Steel Stainless Steel is corrosion resistant!! trade name due to chromium oxide on the surface of the metal S.S. Series 200 and 300 … Austenitic nonmagnetic high formability very high corrosion resistance twice the cost of ferritic S.S. 400 … Ferritic or Martensitic poor ductility and formability lowest cost S.S. 500 … Martensitic high strength 1.5 times the cost of ferritic S.S.

36 Tool steel are generally used in a heat-treated state.
Refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Characteristics include high hardness, resistance to abrasion (excellent wear), an ability to hold a cutting edge, resistance to deformation at elevated temperatures (red-hardness). Tool steel are generally used in a heat-treated state. High carbon content – very brittle Wear Resistant, High Strength and Tough High Carbon steels Modified by alloy additions AISI-SAE Classification Letter & Number Identification

37 Tool Steel AISI-SAE tool steel grades[1]
Defining property AISI-SAE grade Significant characteristics Water-hardening W Cold-working O Oil-hardening A Air-hardening; medium alloy D High carbon; high chromium Shock resisting S High speed T Tungsten base M Molybdenum base Hot-working H H1-H19: chromium base H20-H39: tungsten base H40-H59: molybdenum base Plastic mold P Special purpose L Low alloy F Carbon tungsten Classification Letters pertain to significant characteristic W,O,A,D,S,T,M,H,P,L,F E.g. A is Air-Hardening medium alloy Numbers pertain to material type 1 thru 7 E.g. 2 is Cold-work An A2 is an Air-Hardenable, Cold-worked material. Read book and look at table 6-6

38 THANKS !!!


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