SlideShare a Scribd company logo
1 of 14
 Heat Treatment involves various heating and
cooling procedures performed to effect
structural changes in a material, which turn
affect its mechanical properties.
Heat treatment is an important operation in the
manufacturing process of many machine
parts and tools. Only by it we can impart high
mechanical properties to the various metal.
 Improve hardness, strength, ductility,
toughness etc.
 Relieve internal stress.
 Eliminate structural inhomogenity.
 Improve machinability.
 Refine grain size and structure.
 Improve wear resistance.
 Overheating- Heating for long periods at
temperatures considerably exceeding the
normal values.
Remedies:-
1. For slight overheating-apply normal
annealing and normalising.
2. For more apply double annealing and
normalising.
 Burning- Heating for a long period at a high
temperature in an oxidation atmosphere or at
temperatures near the melting point.
Remedies:-
1. 1st stage- use homogenising followed by
double annealing.
2. 2nd stage- use forging followed by
annealing.
3. 3rd stage- defect can not remedied.
 Oxidation- Thick layer of scale on the surface
of the steel article. Oxidation atmosphere in
the heating furnace is the caused.
Remedies:-
1. Heat in furnaces with reducing , neutral or
protective atmospheres.
2. Heat in boxes with used carburising agent
or cast iron chips.
3. Heat in molten salt bathes.
 Decarburisation- loss of carbon in the suface
layers of the articles. This is due to the
oxidising atmosphere in the heating furnace.
Remedies:-
1. Heat in furnaces with reducing, neutral or
protective atmosphere.
2. Machine off the decarburised layer if the
machining allowances is sufficiently large.
3. Heat in molten salt bath.
4. Heat in boxes with used carburising agent.
 Quenching cracks- this is due to the internal
stresses due to volume changes at
temperature, caused by martensitic transfo
rmation.
Remedies:-
1. Avoiding sharp projections ,sharp corners
,and sudden transitions from thick to thin
sections .
2. Apply austempering.
3. Temper immidiately after quenching.
4. Heat to the minimum suitable temperature
for hardening.
 Warping- asymmetrical deformation of the
articles in quenching. This is due to volume
changes in cooling or heating, non-uniform
heating, internal stresses etc.
Remedies:-
1. Cool slowly in the martensitic range.
2. Apply surface hardening.
3. Heat uniformly for hardening.
4. Quench as uniformly as possible in
hardening.
 Soft spots- zones on the surface of hardened
articles with lower hardness due to
decarburizations and inhomogeneity of
structure.
Remedies:-
1. Using more effective quenching medium.
2. Obtaining a more homogenous structure ,
employing annealing or normalising before
hardening.
3. Protecting against decarburisation in
heating.
 Erosion –reduction in size of the articles or
loss of metals from its surface due to
chemical reactios of chlorous salts and
oxidation of metals.
Remedies-
1. Deoxidised salt bath with borax or
ferrosilicon should be used.
2. Properly position the article in reference to
the electrodes of electrical salt bath.
 Corrosion- pitting or groove or nonuniform
scale formation type destruction of the
surface of an article due to heating in flame
furnace , salt bath composition and
oxidation.
Remedies –
1. Carefully control salt composition.
2. Deoxidise the bath.
3. Eliminate the oxidising temperature
atmosphere when heating in flame
hardening.
The main types of rejects in annealing and
normalising are due to faulty regulation of
heating temerature, including overheating,
burning, underheating, etc….
THANK YOU

More Related Content

What's hot (20)

Heat treatment of steels- I
Heat treatment of steels- IHeat treatment of steels- I
Heat treatment of steels- I
 
Iron Carbon diagram
Iron Carbon diagramIron Carbon diagram
Iron Carbon diagram
 
METAL FORMING PROCESS
METAL FORMING PROCESSMETAL FORMING PROCESS
METAL FORMING PROCESS
 
Sheet Metal Forming
Sheet Metal FormingSheet Metal Forming
Sheet Metal Forming
 
Microstructures
MicrostructuresMicrostructures
Microstructures
 
Induction Hardening and Flame Hardening
Induction Hardening and Flame HardeningInduction Hardening and Flame Hardening
Induction Hardening and Flame Hardening
 
POWDER METALLURGY
POWDER METALLURGYPOWDER METALLURGY
POWDER METALLURGY
 
Heat treatment process
Heat treatment processHeat treatment process
Heat treatment process
 
Quenching, tempering, normalizing, annealing, do you know clearly?
Quenching, tempering, normalizing, annealing, do you know clearly?Quenching, tempering, normalizing, annealing, do you know clearly?
Quenching, tempering, normalizing, annealing, do you know clearly?
 
Welding metallurgy
Welding metallurgyWelding metallurgy
Welding metallurgy
 
Rolling process
Rolling processRolling process
Rolling process
 
Austempering and Martempering in Metallurgy
Austempering and Martempering in Metallurgy Austempering and Martempering in Metallurgy
Austempering and Martempering in Metallurgy
 
Gating and riser in casting
Gating  and riser in castingGating  and riser in casting
Gating and riser in casting
 
Mg alloys
Mg alloysMg alloys
Mg alloys
 
Cast Iron
Cast IronCast Iron
Cast Iron
 
Alloy Steel
Alloy SteelAlloy Steel
Alloy Steel
 
01 fundamentals of metalworking
01 fundamentals of metalworking01 fundamentals of metalworking
01 fundamentals of metalworking
 
SOLIDIFICATION OF CASTING
SOLIDIFICATION OF CASTINGSOLIDIFICATION OF CASTING
SOLIDIFICATION OF CASTING
 
Heat Treatment Processes
Heat Treatment ProcessesHeat Treatment Processes
Heat Treatment Processes
 
Types of steels
Types of  steelsTypes of  steels
Types of steels
 

Similar to Heat treatment defects &and its remedies

The Basics Of Heat Treatment.pdf
The Basics Of Heat Treatment.pdfThe Basics Of Heat Treatment.pdf
The Basics Of Heat Treatment.pdfHardcastle Petrofer
 
Heat treatment process
Heat treatment processHeat treatment process
Heat treatment processHiren Gohil
 
MEng 3202 Chapter Four April 11, 2023 (1).pptx
MEng 3202 Chapter Four April 11, 2023 (1).pptxMEng 3202 Chapter Four April 11, 2023 (1).pptx
MEng 3202 Chapter Four April 11, 2023 (1).pptxBarsena
 
Heat treatment process
Heat treatment processHeat treatment process
Heat treatment processAmrendra Kumar
 
Heat tratment bykotkar ss
Heat tratment bykotkar ssHeat tratment bykotkar ss
Heat tratment bykotkar sssuyog kotkar
 
Heat treatment(Muda Ibrahim)
Heat treatment(Muda Ibrahim)Heat treatment(Muda Ibrahim)
Heat treatment(Muda Ibrahim)Muda Ibrahim
 
Heat treatment Process
Heat treatment ProcessHeat treatment Process
Heat treatment ProcessKeval Patil
 
Heat treatment processes
Heat treatment processesHeat treatment processes
Heat treatment processesSaiGayathri12
 
Solo swiss heat treatment glossary
Solo swiss heat treatment glossarySolo swiss heat treatment glossary
Solo swiss heat treatment glossarySOLO Swiss SA
 
3.Hot Working Pt1 - Complete (2).ppt
3.Hot Working Pt1 - Complete (2).ppt3.Hot Working Pt1 - Complete (2).ppt
3.Hot Working Pt1 - Complete (2).pptcryeshot
 
Affecting mechanical properties
Affecting mechanical propertiesAffecting mechanical properties
Affecting mechanical propertiesSenthil Arasan
 
Mechanical working of metals
Mechanical working of metalsMechanical working of metals
Mechanical working of metalsNaman Dave
 
The International Journal of Engineering and Science (IJES)
The International Journal of Engineering and Science (IJES)The International Journal of Engineering and Science (IJES)
The International Journal of Engineering and Science (IJES)theijes
 
Annealing , normalizing , quenching , martensitic transformation (1)
Annealing , normalizing , quenching , martensitic transformation (1)Annealing , normalizing , quenching , martensitic transformation (1)
Annealing , normalizing , quenching , martensitic transformation (1)thiru1mech
 

Similar to Heat treatment defects &and its remedies (20)

The Basics Of Heat Treatment.pdf
The Basics Of Heat Treatment.pdfThe Basics Of Heat Treatment.pdf
The Basics Of Heat Treatment.pdf
 
Heat treatment process
Heat treatment processHeat treatment process
Heat treatment process
 
MEng 3202 Chapter Four April 11, 2023 (1).pptx
MEng 3202 Chapter Four April 11, 2023 (1).pptxMEng 3202 Chapter Four April 11, 2023 (1).pptx
MEng 3202 Chapter Four April 11, 2023 (1).pptx
 
Heat treatment process
Heat treatment processHeat treatment process
Heat treatment process
 
Heat tratment bykotkar ss
Heat tratment bykotkar ssHeat tratment bykotkar ss
Heat tratment bykotkar ss
 
Heat treatment(Muda Ibrahim)
Heat treatment(Muda Ibrahim)Heat treatment(Muda Ibrahim)
Heat treatment(Muda Ibrahim)
 
Heat treatment Process
Heat treatment ProcessHeat treatment Process
Heat treatment Process
 
Heat treatment processes
Heat treatment processesHeat treatment processes
Heat treatment processes
 
Solo swiss heat treatment glossary
Solo swiss heat treatment glossarySolo swiss heat treatment glossary
Solo swiss heat treatment glossary
 
Heat Treatments
Heat TreatmentsHeat Treatments
Heat Treatments
 
Heat treatment
Heat treatmentHeat treatment
Heat treatment
 
3.Hot Working Pt1 - Complete (2).ppt
3.Hot Working Pt1 - Complete (2).ppt3.Hot Working Pt1 - Complete (2).ppt
3.Hot Working Pt1 - Complete (2).ppt
 
MODULE-3.pptx
MODULE-3.pptxMODULE-3.pptx
MODULE-3.pptx
 
Heat Treatment
Heat TreatmentHeat Treatment
Heat Treatment
 
Affecting mechanical properties
Affecting mechanical propertiesAffecting mechanical properties
Affecting mechanical properties
 
Mechanical working of metals
Mechanical working of metalsMechanical working of metals
Mechanical working of metals
 
Mechanical working of metals
Mechanical working of metalsMechanical working of metals
Mechanical working of metals
 
The International Journal of Engineering and Science (IJES)
The International Journal of Engineering and Science (IJES)The International Journal of Engineering and Science (IJES)
The International Journal of Engineering and Science (IJES)
 
Heat treatment of steel
Heat treatment of steelHeat treatment of steel
Heat treatment of steel
 
Annealing , normalizing , quenching , martensitic transformation (1)
Annealing , normalizing , quenching , martensitic transformation (1)Annealing , normalizing , quenching , martensitic transformation (1)
Annealing , normalizing , quenching , martensitic transformation (1)
 

More from NIAJ AHMED

cost calculation on forging
 cost calculation on forging  cost calculation on forging
cost calculation on forging NIAJ AHMED
 
Rotary forging OR Orbital forging
Rotary forging OR Orbital forgingRotary forging OR Orbital forging
Rotary forging OR Orbital forgingNIAJ AHMED
 
Sandip presentation final
Sandip presentation finalSandip presentation final
Sandip presentation finalNIAJ AHMED
 
Presentation1 kjl
Presentation1 kjlPresentation1 kjl
Presentation1 kjlNIAJ AHMED
 
ISOTHERMAL FORGING
ISOTHERMAL FORGINGISOTHERMAL FORGING
ISOTHERMAL FORGINGNIAJ AHMED
 
Niaz presentation1
Niaz presentation1Niaz presentation1
Niaz presentation1NIAJ AHMED
 

More from NIAJ AHMED (7)

cost calculation on forging
 cost calculation on forging  cost calculation on forging
cost calculation on forging
 
Rotary forging OR Orbital forging
Rotary forging OR Orbital forgingRotary forging OR Orbital forging
Rotary forging OR Orbital forging
 
Sandip presentation final
Sandip presentation finalSandip presentation final
Sandip presentation final
 
Presentation1 kjl
Presentation1 kjlPresentation1 kjl
Presentation1 kjl
 
Ductile iron
Ductile ironDuctile iron
Ductile iron
 
ISOTHERMAL FORGING
ISOTHERMAL FORGINGISOTHERMAL FORGING
ISOTHERMAL FORGING
 
Niaz presentation1
Niaz presentation1Niaz presentation1
Niaz presentation1
 

Recently uploaded

Energy Awareness training ppt for manufacturing process.pptx
Energy Awareness training ppt for manufacturing process.pptxEnergy Awareness training ppt for manufacturing process.pptx
Energy Awareness training ppt for manufacturing process.pptxsiddharthjain2303
 
The SRE Report 2024 - Great Findings for the teams
The SRE Report 2024 - Great Findings for the teamsThe SRE Report 2024 - Great Findings for the teams
The SRE Report 2024 - Great Findings for the teamsDILIPKUMARMONDAL6
 
home automation using Arduino by Aditya Prasad
home automation using Arduino by Aditya Prasadhome automation using Arduino by Aditya Prasad
home automation using Arduino by Aditya Prasadaditya806802
 
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsync
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsyncWhy does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsync
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsyncssuser2ae721
 
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdfCCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdfAsst.prof M.Gokilavani
 
Concrete Mix Design - IS 10262-2019 - .pptx
Concrete Mix Design - IS 10262-2019 - .pptxConcrete Mix Design - IS 10262-2019 - .pptx
Concrete Mix Design - IS 10262-2019 - .pptxKartikeyaDwivedi3
 
Past, Present and Future of Generative AI
Past, Present and Future of Generative AIPast, Present and Future of Generative AI
Past, Present and Future of Generative AIabhishek36461
 
Instrumentation, measurement and control of bio process parameters ( Temperat...
Instrumentation, measurement and control of bio process parameters ( Temperat...Instrumentation, measurement and control of bio process parameters ( Temperat...
Instrumentation, measurement and control of bio process parameters ( Temperat...121011101441
 
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfg
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfgUnit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfg
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfgsaravananr517913
 
Steel Structures - Building technology.pptx
Steel Structures - Building technology.pptxSteel Structures - Building technology.pptx
Steel Structures - Building technology.pptxNikhil Raut
 
Class 1 | NFPA 72 | Overview Fire Alarm System
Class 1 | NFPA 72 | Overview Fire Alarm SystemClass 1 | NFPA 72 | Overview Fire Alarm System
Class 1 | NFPA 72 | Overview Fire Alarm Systemirfanmechengr
 
IVE Industry Focused Event - Defence Sector 2024
IVE Industry Focused Event - Defence Sector 2024IVE Industry Focused Event - Defence Sector 2024
IVE Industry Focused Event - Defence Sector 2024Mark Billinghurst
 
System Simulation and Modelling with types and Event Scheduling
System Simulation and Modelling with types and Event SchedulingSystem Simulation and Modelling with types and Event Scheduling
System Simulation and Modelling with types and Event SchedulingBootNeck1
 
complete construction, environmental and economics information of biomass com...
complete construction, environmental and economics information of biomass com...complete construction, environmental and economics information of biomass com...
complete construction, environmental and economics information of biomass com...asadnawaz62
 
Introduction-To-Agricultural-Surveillance-Rover.pptx
Introduction-To-Agricultural-Surveillance-Rover.pptxIntroduction-To-Agricultural-Surveillance-Rover.pptx
Introduction-To-Agricultural-Surveillance-Rover.pptxk795866
 
Software and Systems Engineering Standards: Verification and Validation of Sy...
Software and Systems Engineering Standards: Verification and Validation of Sy...Software and Systems Engineering Standards: Verification and Validation of Sy...
Software and Systems Engineering Standards: Verification and Validation of Sy...VICTOR MAESTRE RAMIREZ
 
Correctly Loading Incremental Data at Scale
Correctly Loading Incremental Data at ScaleCorrectly Loading Incremental Data at Scale
Correctly Loading Incremental Data at ScaleAlluxio, Inc.
 
Solving The Right Triangles PowerPoint 2.ppt
Solving The Right Triangles PowerPoint 2.pptSolving The Right Triangles PowerPoint 2.ppt
Solving The Right Triangles PowerPoint 2.pptJasonTagapanGulla
 
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)Dr SOUNDIRARAJ N
 

Recently uploaded (20)

Energy Awareness training ppt for manufacturing process.pptx
Energy Awareness training ppt for manufacturing process.pptxEnergy Awareness training ppt for manufacturing process.pptx
Energy Awareness training ppt for manufacturing process.pptx
 
The SRE Report 2024 - Great Findings for the teams
The SRE Report 2024 - Great Findings for the teamsThe SRE Report 2024 - Great Findings for the teams
The SRE Report 2024 - Great Findings for the teams
 
home automation using Arduino by Aditya Prasad
home automation using Arduino by Aditya Prasadhome automation using Arduino by Aditya Prasad
home automation using Arduino by Aditya Prasad
 
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsync
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsyncWhy does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsync
Why does (not) Kafka need fsync: Eliminating tail latency spikes caused by fsync
 
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdfCCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
CCS355 Neural Networks & Deep Learning Unit 1 PDF notes with Question bank .pdf
 
Concrete Mix Design - IS 10262-2019 - .pptx
Concrete Mix Design - IS 10262-2019 - .pptxConcrete Mix Design - IS 10262-2019 - .pptx
Concrete Mix Design - IS 10262-2019 - .pptx
 
Past, Present and Future of Generative AI
Past, Present and Future of Generative AIPast, Present and Future of Generative AI
Past, Present and Future of Generative AI
 
Instrumentation, measurement and control of bio process parameters ( Temperat...
Instrumentation, measurement and control of bio process parameters ( Temperat...Instrumentation, measurement and control of bio process parameters ( Temperat...
Instrumentation, measurement and control of bio process parameters ( Temperat...
 
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfg
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfgUnit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfg
Unit7-DC_Motors nkkjnsdkfnfcdfknfdgfggfg
 
Steel Structures - Building technology.pptx
Steel Structures - Building technology.pptxSteel Structures - Building technology.pptx
Steel Structures - Building technology.pptx
 
Class 1 | NFPA 72 | Overview Fire Alarm System
Class 1 | NFPA 72 | Overview Fire Alarm SystemClass 1 | NFPA 72 | Overview Fire Alarm System
Class 1 | NFPA 72 | Overview Fire Alarm System
 
IVE Industry Focused Event - Defence Sector 2024
IVE Industry Focused Event - Defence Sector 2024IVE Industry Focused Event - Defence Sector 2024
IVE Industry Focused Event - Defence Sector 2024
 
System Simulation and Modelling with types and Event Scheduling
System Simulation and Modelling with types and Event SchedulingSystem Simulation and Modelling with types and Event Scheduling
System Simulation and Modelling with types and Event Scheduling
 
complete construction, environmental and economics information of biomass com...
complete construction, environmental and economics information of biomass com...complete construction, environmental and economics information of biomass com...
complete construction, environmental and economics information of biomass com...
 
Introduction-To-Agricultural-Surveillance-Rover.pptx
Introduction-To-Agricultural-Surveillance-Rover.pptxIntroduction-To-Agricultural-Surveillance-Rover.pptx
Introduction-To-Agricultural-Surveillance-Rover.pptx
 
POWER SYSTEMS-1 Complete notes examples
POWER SYSTEMS-1 Complete notes  examplesPOWER SYSTEMS-1 Complete notes  examples
POWER SYSTEMS-1 Complete notes examples
 
Software and Systems Engineering Standards: Verification and Validation of Sy...
Software and Systems Engineering Standards: Verification and Validation of Sy...Software and Systems Engineering Standards: Verification and Validation of Sy...
Software and Systems Engineering Standards: Verification and Validation of Sy...
 
Correctly Loading Incremental Data at Scale
Correctly Loading Incremental Data at ScaleCorrectly Loading Incremental Data at Scale
Correctly Loading Incremental Data at Scale
 
Solving The Right Triangles PowerPoint 2.ppt
Solving The Right Triangles PowerPoint 2.pptSolving The Right Triangles PowerPoint 2.ppt
Solving The Right Triangles PowerPoint 2.ppt
 
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)
UNIT III ANALOG ELECTRONICS (BASIC ELECTRONICS)
 

Heat treatment defects &and its remedies

  • 1.
  • 2.  Heat Treatment involves various heating and cooling procedures performed to effect structural changes in a material, which turn affect its mechanical properties. Heat treatment is an important operation in the manufacturing process of many machine parts and tools. Only by it we can impart high mechanical properties to the various metal.
  • 3.  Improve hardness, strength, ductility, toughness etc.  Relieve internal stress.  Eliminate structural inhomogenity.  Improve machinability.  Refine grain size and structure.  Improve wear resistance.
  • 4.
  • 5.  Overheating- Heating for long periods at temperatures considerably exceeding the normal values. Remedies:- 1. For slight overheating-apply normal annealing and normalising. 2. For more apply double annealing and normalising.
  • 6.  Burning- Heating for a long period at a high temperature in an oxidation atmosphere or at temperatures near the melting point. Remedies:- 1. 1st stage- use homogenising followed by double annealing. 2. 2nd stage- use forging followed by annealing. 3. 3rd stage- defect can not remedied.
  • 7.  Oxidation- Thick layer of scale on the surface of the steel article. Oxidation atmosphere in the heating furnace is the caused. Remedies:- 1. Heat in furnaces with reducing , neutral or protective atmospheres. 2. Heat in boxes with used carburising agent or cast iron chips. 3. Heat in molten salt bathes.
  • 8.  Decarburisation- loss of carbon in the suface layers of the articles. This is due to the oxidising atmosphere in the heating furnace. Remedies:- 1. Heat in furnaces with reducing, neutral or protective atmosphere. 2. Machine off the decarburised layer if the machining allowances is sufficiently large. 3. Heat in molten salt bath. 4. Heat in boxes with used carburising agent.
  • 9.  Quenching cracks- this is due to the internal stresses due to volume changes at temperature, caused by martensitic transfo rmation. Remedies:- 1. Avoiding sharp projections ,sharp corners ,and sudden transitions from thick to thin sections . 2. Apply austempering. 3. Temper immidiately after quenching. 4. Heat to the minimum suitable temperature for hardening.
  • 10.  Warping- asymmetrical deformation of the articles in quenching. This is due to volume changes in cooling or heating, non-uniform heating, internal stresses etc. Remedies:- 1. Cool slowly in the martensitic range. 2. Apply surface hardening. 3. Heat uniformly for hardening. 4. Quench as uniformly as possible in hardening.
  • 11.  Soft spots- zones on the surface of hardened articles with lower hardness due to decarburizations and inhomogeneity of structure. Remedies:- 1. Using more effective quenching medium. 2. Obtaining a more homogenous structure , employing annealing or normalising before hardening. 3. Protecting against decarburisation in heating.
  • 12.  Erosion –reduction in size of the articles or loss of metals from its surface due to chemical reactios of chlorous salts and oxidation of metals. Remedies- 1. Deoxidised salt bath with borax or ferrosilicon should be used. 2. Properly position the article in reference to the electrodes of electrical salt bath.
  • 13.  Corrosion- pitting or groove or nonuniform scale formation type destruction of the surface of an article due to heating in flame furnace , salt bath composition and oxidation. Remedies – 1. Carefully control salt composition. 2. Deoxidise the bath. 3. Eliminate the oxidising temperature atmosphere when heating in flame hardening.
  • 14. The main types of rejects in annealing and normalising are due to faulty regulation of heating temerature, including overheating, burning, underheating, etc…. THANK YOU