INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com
HISTORY
 INTRODUCTION
 COMPOSITION
 CRYTAL SRUCTURE
 CLASSIFICATION
 FERRITIC
 MARTENSITIC
 AUSTENITIC


www.india...
PROPERTIES
 MODULUS OF ELASTICITY : YOUNGS
MODULUS(ELASTIC MODULE)
 MECHANICAL PROPERTIES
 DUCTILITY
 MALLEABILITY
 S...
HEAT TREATMENT
 CORROSION RESISTANCE




USES OF STAINLESS STEEL IN
ORTHODONTICS

www.indiandentalacademy.com
The corrosion resistance of iron-chromium
alloys was first recognized in 1821 by the
French metallurgist Pierre Berthier
...
INTRODUCTION


Steels are iron based alloys that contain
less than 1.2% carbon



When 12-30% chromium is added to steel...
IRON
Fe - derived from Latin word ferrum.
Atomic number-26; melting point 1535°C.
Iron is the 4th common element in the
ea...
CHROMIUM


Chromium is extracted by a process
known as Goldschmidt's alumino
thermic process.



The corrosion resistanc...
SILICON



Improves resistance to oxidation at higher
temperature and to corrosion.

www.indiandentalacademy.com
NICKEL
Its principal ores are
 Garnierite
 Nickel Glance
 Nickel is extracted by a process known as
Monds Process.
 Ni...
CARBON



Provides strength and hardness and it
increases corrosion.

www.indiandentalacademy.com
MANGANESE AND
MOLYBDENUM



Increases strength and retains ductility
and malleability of iron

www.indiandentalacademy.co...
CORROSION RESISTANCE
PASSIVATION
The corrosion resistance of stainless steel
is largely due to passivating effect of
chrom...
SENSITISATION


Carbon is an undesirable impurity in
stainless steel.



Carbon does not enter into the physical
structu...


But at temperature between 800 - 1200 ºc
carbon reacts with chromium to form
chromium carbide.



This is harmless in ...
STABILIZATION


Addition of small amounts (about 6 times
carbon) of niobium or titanium with
tantalum stabilizes stainles...
PRECAUTIONS TO REDUCE
CORROSION RESISTANCE


Do not heat the article above 350 ºc for a
longtime



Brazing temperature ...


Do not use carbon steel instruments for
manipulation of wires



Do not use chlorine or fluorine containing
cleansers
...
CRYTAL SRUCTURE
BCC

BCT

www.indiandentalacademy.com

FCC
CLASSIFICATION
Based on lattice arrangements

Ferritic (bcc)

Austenitic (fcc)

Martenistic (bct)
 Based on carbon con...
According to American iron and steel
institute

300 – 502
 According to Anderson

Soft

Half-hard

Hard


www.indian...


FERRITIC



MARTENSITIC



AUSTENITIC
www.indiandentalacademy.com


Ferrite is iron which contains practically no carbon. The light parts of
the micrograph are ferrite crystals. These are...







Martensitic steels have a higher carbon content than
ferritic steels. The carbide particles are closely packed...








In austenitic steels the grain boundaries are
narrow straight lines. In this case also, we find
precipitatio...
COMPOSITION OF THREE DIFFERENT
TYPES OF STAINLESS STEEL
Type of
space lattice

Chromium Nickel
%
%

Carbon
%

Ferritic
b.c...
PROPERTIES
Bio compatibility
 High corrosion resistance
 Chemically stable in oral or implant
environment
 Good ductili...
Less critical grain growth
 Fairly high formability factor
 Melting tempreture 1240 – 1260 ºc
 Respond to heat treatmen...


Most of these properties are required for
selection for orthodontic appliances

www.indiandentalacademy.com
MODULUS OF ELASTICITY : YOUNGS
MODULUS(ELASTIC MODULE)


Ratio of stress to strain.



The SI unit of modulus of elastic...
MECHANICAL PROPERTIES
Yield strength

1100 – 1750 Mpa

Ultimate tensile strength

2200 Mpa

Modulus of elasticity
Surface ...
DUCTILITY


Stainless steel has the ability to be drawn
into wires and withstand permanent
deformation under tensile load...
MALLEABILITY
A malleable metal is capable of being
extended, shaped, or otherwise deformed
without cracking.
 Stainless s...


Stainless steel has the ability to withstand
permanent deformation



Malleable materials can be formed using
stamping...
STRAIN HARDENING OR WORK
HARDENING
If a metal is continuously stressed it
becomes stiffer and harder. Hardening of
a metal...
CONSEQUENCES OF WORK HARDENING

Increased surface hardness
 Greater yield and ultimate strength
 Decreased ductility
 P...
HEAT TREATMENT


It is a general process using thermal
energy to change the charachteristics of
metallic alloy as in temp...
ANNEALING


It is a process that produces conditions by
heating and maintaining at a suitable
temperature, and then cooli...
There are three stages in the annealing
process, with the first being the

Recovery phase

Recrystallization

Grain gro...


The effect associated with cold working
such as strain hardening, low ductility &
distorted grain can be reversed by si...


The high temperature of annealing may
result in oxidation of the metal’s surface,
resulting in tarnish and corrosion.

...
USES OF STAINLESS STEEL IN
ORTHODONTICS
Orthodontic brackets
 Orthodontic bands
 Stainless steel is used for making
auxi...
It can be used for making different
instruments like different types of pliers.
For this austenite stainless steel is used...


Stainless steel wires are used in making
Up righting springs and minisprings.



It is used for making instrument stan...
www.indiandentalacademy.com
Upcoming SlideShare
Loading in …5
×

Stainless steel by ihsan1 /certified fixed orthodontic courses by Indian dental academy

946 views
666 views

Published on



The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078


Published in: Education
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
946
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
11
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Stainless steel by ihsan1 /certified fixed orthodontic courses by Indian dental academy

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. HISTORY  INTRODUCTION  COMPOSITION  CRYTAL SRUCTURE  CLASSIFICATION  FERRITIC  MARTENSITIC  AUSTENITIC  www.indiandentalacademy.com
  3. 3. PROPERTIES  MODULUS OF ELASTICITY : YOUNGS MODULUS(ELASTIC MODULE)  MECHANICAL PROPERTIES  DUCTILITY  MALLEABILITY  STRAIN HARDENING OR WORK HARDENING  www.indiandentalacademy.com
  4. 4. HEAT TREATMENT  CORROSION RESISTANCE   USES OF STAINLESS STEEL IN ORTHODONTICS www.indiandentalacademy.com
  5. 5. The corrosion resistance of iron-chromium alloys was first recognized in 1821 by the French metallurgist Pierre Berthier  First developed by accident by Harry Brearley in Sheffield, England  Stainless steel entered dentistry in the year 1919 – krupp’s dental clinic, Germany by Hauptmeyer  In 1930 Angle used it as ligature wire  www.indiandentalacademy.com
  6. 6. INTRODUCTION  Steels are iron based alloys that contain less than 1.2% carbon  When 12-30% chromium is added to steel the alloy is called stainless steel  Steel exists in three Ferritic, austenitic and martensitic forms. www.indiandentalacademy.com
  7. 7. IRON Fe - derived from Latin word ferrum. Atomic number-26; melting point 1535°C. Iron is the 4th common element in the earth’s crust.  The ores of iron are mainly Haematite, Magnetite, Limonite and siderite. Blast furnace is used for the primary reduction of iron ore to iron.  www.indiandentalacademy.com
  8. 8. CHROMIUM  Chromium is extracted by a process known as Goldschmidt's alumino thermic process.  The corrosion resistance of stainless steel is largely due to the passivating effect of chromium www.indiandentalacademy.com
  9. 9. SILICON  Improves resistance to oxidation at higher temperature and to corrosion. www.indiandentalacademy.com
  10. 10. NICKEL Its principal ores are  Garnierite  Nickel Glance  Nickel is extracted by a process known as Monds Process.  Nickel stabilizes a homogenous mass and corrosion resistant austenitic phase at low temperature. Alloying with nickel improves the corrosion resistance to oxidizing acids.  www.indiandentalacademy.com
  11. 11. CARBON  Provides strength and hardness and it increases corrosion. www.indiandentalacademy.com
  12. 12. MANGANESE AND MOLYBDENUM  Increases strength and retains ductility and malleability of iron www.indiandentalacademy.com
  13. 13. CORROSION RESISTANCE PASSIVATION The corrosion resistance of stainless steel is largely due to passivating effect of chromium.  About 11% of chromium is needed to produce corrosion resistance in pure iron.  Chromium resists corrosion well because of the formation of a strongly adherent coating of Cr2O3 on the surface.  www.indiandentalacademy.com
  14. 14. SENSITISATION  Carbon is an undesirable impurity in stainless steel.  Carbon does not enter into the physical structure of these steels. www.indiandentalacademy.com
  15. 15.  But at temperature between 800 - 1200 ºc carbon reacts with chromium to form chromium carbide.  This is harmless in itself. But chromium tied up as the carbide cannot contribute to the corrosion resistance of the metal. This is called sensitization. www.indiandentalacademy.com
  16. 16. STABILIZATION  Addition of small amounts (about 6 times carbon) of niobium or titanium with tantalum stabilizes stainless steel, these arrest temporarily , the diffusion of carbon atom  Stabilized steel becomes more expensive www.indiandentalacademy.com
  17. 17. PRECAUTIONS TO REDUCE CORROSION RESISTANCE  Do not heat the article above 350 ºc for a longtime  Brazing temperature should be low and the time should be short  Select solder of very low fusion temperature www.indiandentalacademy.com
  18. 18.  Do not use carbon steel instruments for manipulation of wires  Do not use chlorine or fluorine containing cleansers  Welding or brazing is performed as quickly as possible i.e. spot welding or laser welding methods are suitable www.indiandentalacademy.com
  19. 19. CRYTAL SRUCTURE BCC BCT www.indiandentalacademy.com FCC
  20. 20. CLASSIFICATION Based on lattice arrangements  Ferritic (bcc)  Austenitic (fcc)  Martenistic (bct)  Based on carbon content(0.8%)  Hypo-eutectoid  Hyper-eutectoid  www.indiandentalacademy.com
  21. 21. According to American iron and steel institute  300 – 502  According to Anderson  Soft  Half-hard  Hard  www.indiandentalacademy.com
  22. 22.  FERRITIC  MARTENSITIC  AUSTENITIC www.indiandentalacademy.com
  23. 23.  Ferrite is iron which contains practically no carbon. The light parts of the micrograph are ferrite crystals. These areas are surrounded by dark lines, which are slightly curved.  The dark points within the ferrite crystals are carbide particles which give the steel its hardness. The carbide precipitation should be situated inside the crystals and not along the boundaries, as this causes a greater susceptibility to corrosion by chemicals,  They have b.c.c structure Good corrosion resistance at low cost Not very strong They have very little application in dentistry    www.indiandentalacademy.com
  24. 24.      Martensitic steels have a higher carbon content than ferritic steels. The carbide particles are closely packed in a matrix of ferrite. The boundaries between the ferrite crystals are seldom clearly defined. As shown by the micrograph, the carbide particles are rather small, rounded and evenly distributed in the steel. It has got f.c.c lattice structure. It has got high strength & hardness. It is used for cutting and surgical instruments. It has got less corrosion resistance compared to other forms. www.indiandentalacademy.com
  25. 25.       In austenitic steels the grain boundaries are narrow straight lines. In this case also, we find precipitation of carbide in the crystals, though to a lesser degree than ferrite, and generally well within the crystals. It has got b.c.t lattice structure It is the most corrosion resistant form They are the most commonly usedby orthodontists in the form of bands and wire Ease of welding Readily over comes sensitization www.indiandentalacademy.com
  26. 26. COMPOSITION OF THREE DIFFERENT TYPES OF STAINLESS STEEL Type of space lattice Chromium Nickel % % Carbon % Ferritic b.c.c 11.5 - 27 0 0.2 max Austenitic f.c.c 16 - 26 7 - 22 0.25 max Martensitic b.c.t 11.5 - 17 0 – 2.5 0.15 – 1.2 www.indiandentalacademy.com
  27. 27. PROPERTIES Bio compatibility  High corrosion resistance  Chemically stable in oral or implant environment  Good ductility and malleability  Undergoes work hardening by large amount ,that is why thinner wires have higher mechanical properties  www.indiandentalacademy.com
  28. 28. Less critical grain growth  Fairly high formability factor  Melting tempreture 1240 – 1260 ºc  Respond to heat treatment  Can be welded and soldered  Easily available in various forms and not expensive  When heated above 400 ºc undergoes sensitization which can be remedied to a certain extend  www.indiandentalacademy.com
  29. 29.  Most of these properties are required for selection for orthodontic appliances www.indiandentalacademy.com
  30. 30. MODULUS OF ELASTICITY : YOUNGS MODULUS(ELASTIC MODULE)  Ratio of stress to strain.  The SI unit of modulus of elasticity is the Pascal. Given the large values typical of many common materials, figures are often quoted in megapascals or gigapascals. Wire with low modulus of elasticity has increased flexibility as compared to a wire of high modulus of elasticity.  www.indiandentalacademy.com
  31. 31. MECHANICAL PROPERTIES Yield strength 1100 – 1750 Mpa Ultimate tensile strength 2200 Mpa Modulus of elasticity Surface hardness 170,000 – 200,000 Mpa 250 – 400 KHN Density 8.5 gm/cc Percentage elongation upto 35% www.indiandentalacademy.com
  32. 32. DUCTILITY  Stainless steel has the ability to be drawn into wires and withstand permanent deformation under tensile load without fracture www.indiandentalacademy.com
  33. 33. MALLEABILITY A malleable metal is capable of being extended, shaped, or otherwise deformed without cracking.  Stainless steel because of its malleability can be used as bands etc.  This property is important in metalworking, as materials that crack or break under pressure cannot be hammered or rolled.  www.indiandentalacademy.com
  34. 34.  Stainless steel has the ability to withstand permanent deformation  Malleable materials can be formed using stamping or form pressing www.indiandentalacademy.com
  35. 35. STRAIN HARDENING OR WORK HARDENING If a metal is continuously stressed it becomes stiffer and harder. Hardening of a metal by cold working is called strain hardening or work hardening  It is a method to produce high tensile strength wire  www.indiandentalacademy.com
  36. 36. CONSEQUENCES OF WORK HARDENING Increased surface hardness  Greater yield and ultimate strength  Decreased ductility  Proportional limit is increased  Decreased resistance to corrosion  No change in elastic modulus  www.indiandentalacademy.com
  37. 37. HEAT TREATMENT  It is a general process using thermal energy to change the charachteristics of metallic alloy as in tempering precipitation, hardening or annealing www.indiandentalacademy.com
  38. 38. ANNEALING  It is a process that produces conditions by heating and maintaining at a suitable temperature, and then cooling very slowly.  It is used to induce softness, relieve internal stresses, refine the structure and improve cold working properties. www.indiandentalacademy.com
  39. 39. There are three stages in the annealing process, with the first being the  Recovery phase  Recrystallization  Grain growth  www.indiandentalacademy.com
  40. 40.  The effect associated with cold working such as strain hardening, low ductility & distorted grain can be reversed by simply heating the metal.  Greater the amount of cold working the more rapidly the effect can be reversed by annealing www.indiandentalacademy.com
  41. 41.  The high temperature of annealing may result in oxidation of the metal’s surface, resulting in tarnish and corrosion. www.indiandentalacademy.com
  42. 42. USES OF STAINLESS STEEL IN ORTHODONTICS Orthodontic brackets  Orthodontic bands  Stainless steel is used for making auxiliaries. Austenitic stainless steel is used for these auxiliaries e.g. Lingual button, Lingual Cleats; Lingual Sheath  Ligature wires are made up of stainless steel wires.  www.indiandentalacademy.com
  43. 43. It can be used for making different instruments like different types of pliers. For this austenite stainless steel is used. For making cutting pliers Martensitic stainless steel is used.  stainless steel wires can be used in fixed orthodontic treatment with edgewise appliances.  www.indiandentalacademy.com
  44. 44.  Stainless steel wires are used in making Up righting springs and minisprings.  It is used for making instrument stands, instrument trays, impression trays etc.  Different gauges of stainless steel round wires are used for the fabrication of different components of removable appliances like clasps, springs, labial bows etc. www.indiandentalacademy.com
  45. 45. www.indiandentalacademy.com

×