Nitriding and carbonitriding copy

Metalurgy

1. Today we will discuss about

2. Introduction
BASITALIKHAN (2012-IM-124)
PRESENTED BY

3. OUTLINESof our Presentation
We have features for every step of the way
Introduction
to Processes
Mechanism/
Procedure
Example &
Applications
ADVANTAGES &
DISADVANTAGES

4. Introduction

5. Introduction
Both Processes are Anti-wear
Heat treatments.
Nitriding
&
Carbonitriding

6. NITRIDING
Nitridingisaheattreatingprocessthat
diffusesnitrogenintothesurfaceofametalto
createacasehardenedsurface.
Nitridingofsteelsproduceslessdistortion
anddeformationthaneithercarburizingor
conventionalhardening.

7. NITRIDING
Theseprocessesaremostcommonlyusedon
low-carbon,low-alloysteels.
Howevertheyarealsousedonmediumand
high-carbonsteels,titanium,aluminumand
molybdenum.

8. Carbonitriding
CARBONITRIDING
Carbonitridingisametallurgicalsurfacemodification
techniquethatisusedtoincreasethesurface
hardnessofametal,therebyreducingwear.
Incarbonitriding,atomsofcarbonandnitrogen
diffuseinterstitiallyintothemetal,creatingbarriers
toslip,increasingthehardnessandmodulusnear
thesurface.

9. MECHANISM
\
PROCEDURE
Carbonitriding is often applied to inexpensive, easily
machined low carbon steel to impart the surface
properties of more expensive and difficult to work
grades of steel.
Surface hardness of carbonitrided parts ranges from
55 to 62 HRC.
Carbonitriding

11. Introduction
NITRIDING
MECHANISM / PROCEDURE

12. MECHANISM OF NITRIDING
NITRIDING.
•Case-hardeningprocess.
•Solidferrousalloy.
•Diffusenitrogen.
•Atsomesuitabletemperature.

13. MEHANISM OF NITRIDING
gas nitriding .
Salt bath nitriding.
plasma nitriding.

14. MEHANISM OF NITRIDING
•Gas Nitriding
•Case-Hardening Process
•Nitrogen Introduction
•Surface of a Solid Ferrous Alloy
•Nitrogenous Gas
•Ammonia
Chemical Reaction
•Nitrogen & Iron
•Core Properties Not Effected
Temperature Range
•495 -565 ºC
•Below Tempering Temperature
White Layer By-Product
•Thin
•Hard Iron Nitride

15. •Chemical Reaction

17. MEHANISM OF NITRIDING
•Salt bath NITRIDING
•Thermo-chemicalDiffusionTreatment
•Hardening Components With
Repeatability.
•Use salt nitrogen-containing
•Salt Bath, at sub-Critical Temperatures.
•Higher diffusion nitrogen
•Corrosion Protection

19. MEHANISM OF NITRIDING
•Vacuum Chamber
•Pressure = 0.64 Pa
•Pre-Heat Cycle
•Surface Cleaning
•Intense electric field.
•Control Gas Flow
•N, H, CH4
•Ionization by Voltage
•Blue-Violet Glow
•Wear Resistant Layer
•PLASMA NITRIDING

21. MEHANISM OF NITRIDING

22. Introduction
CARBONITRIDING
MECHANISM / PROCEDURE

23. Carbonitridingissimilartogascarburization
withtheadditionofammoniatothe
carburizingatmosphere,whichprovidesa
sourceofnitrogen.

24. Nascentnitrogenformsatthework
surfacebythedissociationofammoniain
thefurnaceatmosphere;thenitrogen
diffusesintothesteelsimultaneously
withcarbon.

25. Typically,carbonitridingiscarriedoutat
alowertemperatureandforashorter
timethanisgascarburizing,producinga
shallowercasethanisusualinproduction
carburizing.

26. CARBONITRIDING IN FC-35
ATMOSPHERE
Ammonia and CO2 flows are
maintained constant through out the
process during Carbonitridingin the
FC35 process.
A typical Carbonitridingprocess cycle
using the FC35

27. Nitriding/Carbonitriding Furnace

28. Carbonitriding(around850°C/1550°F)iscarried
outattemperaturessubstantiallyhigherthanplain
nitriding(around530°C/990°F)butslightly
lowerthanthoseusedforcarburizing(around950
°C/1700°F)andforshortertimes.
A typical Carbonitridingprocess cycle using the
FC35

29. Carbonitridingformsahard,wear-resistantcase,is
typically0.07mmto0.5mmthick.
Maximumcasedepthistypicallyrestrictedto
0.75mm;casedepthsgreaterthanthistaketoolong
todiffusetobeeconomical.
Itscarriedoutinasaltbathorinafurnacegas
atmosphere.

31. Aircraft Industry

32. Aircraft Industry

33. Military technology

34. Military technology

35. Automotive Industry

36. Internal combustion engines
Compressors

37. Crank Shafts, Cam shafts, Gears etc.

38. Tools & Dies

40. Itgiveshighsurfacehardness.
Nitridingincreasewearresistance.
Itincreasethetensilestrengthand
yieldpoint.
Improvesfatiguelifeby30%to100%.
Itisgoodforhightemperature
applications.
ADVANTAGES

41. It has a greater resistance to softening
duringTempering.
The carbonitridedcase has better wear
and temper resistance than a straight
carburized case.
It is carried out at a lower temperature
and for a shorter time than is gas
carburizing.
Reduced distortion due to lower
temperature.
ADVANTAGES

42. Since nitridedparts are not quenched,
this minimizes distortion or cracking.
Whereas in a carburized part, hardness
begins to fall at about 200°C, a nitrided
part retains hardness up to 500°C.
No machining is required after nitriding.
Some complex parts which are not
carburized satisfactorily, can be nitrided
without difficulty.
ADVANTAGES

43. DISADVANTAGES
Asymmetric products could buckle due
to unequal cooling effects
Maximum dimensions are determined
by the furnace dimensions
Blind holes cannot be treated during
plasma -nitriding.
Toughness and impact resistance
decrease

44. DISADVANTAGES
It produces shallower cases.
It is not possible to obtain higher core
hardness and deeper case depths.
Only useful for Plain carbon steel or
Low alloy Steel.
Ammonia can produce harmful effects.
Long cycle times (40 to 100 hours).

45. DISADVANTAGES
The brittle case formed is Brittle.
Only special alloy steels (containing Al, Cr
and V) can be satisfactorily treated.
High cost of the nitriding process.
Technical control required.
If a nitridedcomponent is accidentally
overheated, the surface hardness will be lost
completely and the component must be
nitridedagain.

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47. THANK YOU
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