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APPLICATIONS OF STEELS CLASS NOTES FOR MECHANICAL ENGINEERING

APPLICATIONS OF STEELS 

CLASS NOTES FOR

 MECHANICAL ENGINEERING

 FERROUS STEELS

                  Structural steel   

Non- structural steel

Carbon steels With C < 0.8 %
Low Alloy Steel with alloying elements < 10 %
High Alloy Steel with alloying elements > 10 %
Tool Steel with C > 0.9 % &C< 1.5 %
Die steel  with
C >1.5 % & C< 2 %

SAE  CLASSIFICATION OF STEELS  (SAE=Society of Automotive Engineers)

 OR

AISI (American Iron and Steel Institute)

Normally a four digit number for steel
(a) 1st digit tells the type of steel
(b)  2nd digit tells % of most predominant alloying element
(c) 3rd and 4th digits with a decimal represent the average % of carbon. In steel1010, average % of C is 0.10 %.

STEEL APPLICATIONS

Designation SAE/AISI

Type of steel

Practical Applications 

1010
Plain carbon steels
Wires, nails, sheets, chains
23xx
Nickel steel with Ni = 3.5 %
Bridges and low temperature service
3xxx
Ni-Cr steel (it is not a stainless steel)
Armature & Automobiles
40xx
Molybdenum steels, Mo = 0.2 to 0.3 %
Forgings, wrenches
5xxx
Cr steels
ball bearings, Dies, Files, gears
6xxx
Cr-Va steels
Axles, springs with high fatigue strength
7xxx
Tungsten steels
Tool cutting edges
8xxx
Low Ni –Cr-Mo steels
Automobile gears
9xxx
Ni-Cr with low Mo steels
Electrical machinery requiring high        magnetic permeability
 NOTE: ALLOYING ELEMENTS
Second digit represents the percentage of most predominant allowing element.  Steel number becomes of five digits if % of predominant allowing element becomes greater than 10 % . Chose % of alloying element carefully as the cost increases sharply. These are justified only by significant improvement in properties like strength, toughness, improvement in corrosion resistance etc.

  VARIOUS EUTECTOID STEELS

Steel with c < 0.8 % ———Hypo eutectoid steel
Steel with c = 0.8 % ———Eutectoid steel
Steel with c > 0.8 % ———Hypereutectoid steel

CARBON STEELS

Main alloying element is CARBON ( % of C < 2 %)
SPECIAL FEATURES OF PLAIN CARBON STEELS
  1. Decrease in ductility with increase in % of carbon
  2.  Heat treatment improves properties.
  3. Quenching causes distortion and induce internal stresses

APPLICATIONS OF CARBON STEELS

ITEM

MEDIUM CARBON STEELS, C >0.3 % and < 0.5 %

CARBON STEELS  C > 0.5 % and < 1.2 %

(a)Uses of SAE 1010 Steels
(i) Steel tubing
(ii) GI sheet
(iii) GI pipe
(iv) Fence Wire or wires
(v) Rods used in RCC
(vi) Automobile bodies
(vii) Rivets
(viii)Nails
(ix) Stamping
(x) Chains
(b) SAE 1020 STEELS
 easily weldable, brazed and drawn.
(i) Boiler plate
(ii) Boiler tube
(iii)Rolled sections in Structures namely angle irons, channel section, T- sections and I- sections
(iv) Piston pins in automobiles
(a) SAE 1040 Steels(i) Used in forgings(ii)Axles(iii) Shafts
(iv)Gears
(v) Connecting rods
(b) SAE 1050
(i) Forgings of large sizes
(ii) Wire ropes
(iii) Railway rail
(iv) Aero engine cylinders
SAE 1060–1095  Steels(i) Gardening tools(ii) Hammers (iii) Saws
(iv) Shear blades
(v) Wood chisel
(vi) Press dies
(vii) Laminated springs
(viii)Wire springs
(ix) Anvil face
(x) Wrench
(xi) Punch
(xii) Drill
(xiii) Die blocks
(xiv) Steel spokes
(xv) Clutch plates
(xvi)Car Bumpers
(b) SAE 1100
Reamers and Broachers
(c) SAE 1110
(i) Milling cutters
(ii) Taps
(iii) Wood working tools
(d) APPLICATIONS OF SAE 1120
(i) Twist drill
(ii) Cutlery
 
TOOL STEELS
Which contain carbon > 0.8 %.
Sr.No.
Practical application   
Tool Steel
1
Hammers, Sledge hammer, Hacksaw Blades, Shear blades, Slotting tool, milling cutters, Threading dies, Chisels, Vice Jaws, Punch and die
0.76 to 0.90 %  C
 2
Wood file
High carbon steel 0.5 to 0.7 % C
3.
Wood chisel
Forged high carbon steel
 4
Steel File ( Fitting shop)
1095 AISI steel
 5
Turning tools
1 to 1.4 %  C + little (Cr + W), temp limit is 250 0C
6.
Drill Bits
High speed tool steel C=0.65 %, Cr = 3.5 %, V=0.80 % , W = 11.75 %

METALS AND NON-METALS

 Sr. No. Metals Non-Metals
 1.  Metals are solid at room temperature. Mercury is an exception. Non-Metals are solids, liquids and gases at room temperature.
 2.  These are malleable. These change into thin sheets under a compressive load. Non metals are not malleable. These crush under a compressive load.
 3.  These are ductile. These change into wires under a tensile load. These fail after a significant deformation. Solid non metals are brittle. These are very weak under a  tensile load.
 4.  These have a shiny surface. These have a dull surface.
 5.  With oxygen, these form basic oxide. With oxygen, these form acidic oxide.
 6.  These have high boiling point. These have low boiling point.
 7.  These have high melting point.  These have low melting point.
 8. Metals displace hydrogen with acid. There is no effect of acids on most of the non metals.
 9. These are heavy as these have more density. These are light.
10. Metals are good conductors of heat and electricity. Metals are good conductors of heat and electricity.
11. Metals are costly. Non metals are relatively cheap.
12. Metals are usually harder. Most of the non metals are soft.
13. These are electropositive in nature (these donate electrons) These are electronegative in nature.
14. These are not inert. These react. These are inert.
15. These form chlorides which are electrovalent compounds or ionic compounds. These form chlorides which are covalent compounds.
16. Metals are opaque. Nothing is visible even in a thin sheet. Some of these are transparent.
17. Metals produce sound on strike. Non-metals do not produce sound on strike.
18. These are not rust proof. These are rust proof.
19. These are good reducing agents. These are good oxidizing agents.
20. These have 1 to 3 electrons in their outer shell. These have 4 to 8 electrons in their outer shell.

 

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