Final PPT on Project

8/11/2019 Final PPT on Project

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Toughness and Micro-Hardness

studies on ADI subjected to Two step

Austempering Process

Team:

Anurag Singh N.S (1PI08ME017)

Aravind.C (1PI08ME018)

Artik Patel (1PI08ME020)

Under the Guidance of:

Prof D. Sethuram

Assistant Professor,

Mechanical Department,

PESIT, Bangalore.


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CONTENTS

1. Introduction on ADI.

2. LITREATURE SURVEY.

3. What is Austempering.4. Austempering applied to Ductile Iron.

5. Applications.

6. Methodology.7. Expected results.


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Steps to be followed1) Problem formulation

2) Literature survey.3) Obtaining the Ductile iron castings from a permanent

mould.

4) Sample preparations.

5) Two step Austempering heat treatment.

6) An investigation will be taken up to evaluatesystematically the toughness and micro-hardness.

7) Mechanical properties of the material will becompared to steel.

8) Results will be analyzed based on micro-structuralfeatures.

9) Also we are planning to study the variation of micro-hardness.


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Introduction On ADI:

Austempered Ductile Iron (ADI) belongs to the family of

Ductile Iron. Surveys of published literature indicate that

considerable research work has been carried out on ADI.

Austempered Ductile Irons (ADI) are an interesting class of

materials because of their unique microstructure and

interesting properties such as excellent characteristics of

strength, toughness and wear resistance.

When subjected to austempering treatment, ductile iron

transforms to a micro-structure consisting of ferrite andretained austenite .


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Due to the presence of retained austenite ADI

exhibits excellent combination of strength andductility, together with good fatigue and wear

properties.

Obtaining the ADI castings from a permanent mould

has several advantages in terms of finer graphite

nodules, good surface finish and repeatability of

castings.

Reported results of castings produced out ofpermanent moulds indicate that there is an

improvement in mechanical properties.


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LITREATURE SURVEY


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Influence of Two-Step Austempering Heat Treatment

Process on the Mechanical Properties of a Low Manganese

Austempered Ductile Cast Iron (ADI)

Author(s): Susil K.Putatunda, Wayne State University; Avnish Patel,Wayne State University

In this investigation, a low manganese ductile cast iron with predominantly

pearlitic as-cast structure was processed by a unique two-step austempering

process.Two batches of samples were prepared. All the specimens were initially

austenitized at 927C (1700F) for 2 hrs.

The first batch of samples were processed by single step austempering process

at several temperatures whereas the second batch of samples were processed by

two-step austempering process.The effect of this two step austempering heat treatment on the microstructure

and mechanical properties of the material were examined and compared with the

samples processed by single step austempering process.

Test results show significant improvement in mechanical properties of the

material as a result of two step austempering process.


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What is Austempering?

The Austempering process was first pioneered by Edgar C. Bain andEdmund S. Davenport in the 1930s who were working for the United StatesSteel Corporation.

Austempering is an isothermal heat treatment applied to ferrous materials.It produces a microstructure that is stronger and tougher than the

structures resulting typically from conventional heat treatment.

Austempering calls for very precise control of process times andtemperatures.

The Ductile Iron casting is initially heated to Austenitizing temperature toget austenitic matrix. It is then cooled at a faster rate to avoid the formation

of pearlite to an intermediate temperature ranging from 250C to 450C andheld at this temperature for a required length of time.

The part is held at this quench temperature for a recommended time totransform the Austenite into Bainite. The part is then removed from the saltquench and air cooled to room temperature.


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Austempering applied to Ductile Iron

ADI is produced by heat treating ductile cast iron to which sometimes small

amounts of copper, nickel and molybdenum are added to improve

hardness.

The Austempering heat treatment process converts Ductile Iron into ADI.

To improve farther properties of ADI, another heat treatment cycle hasbeen introduced, which is called two step austempering process.

Here the material is quenched to a temperature which is increased just

after quenching to a final temperature.

The final properties of the ADI are governed by the austempering

temperature and duration.


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Austempering Process

One Step Austempering Process Two Step Austempering Process


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Summary of Austenite Transformation


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Applications & Examples:

The properties of ADI coupled with the cost and flexibility benefits of ductile iron castings

means the potential for ADI applications is vast:

Agriculture - excellent resistance to soil wear.

Digger/Grab teeth - high strength and wear resistance.

Industrial - wear components, pumps, etc.

Gears - for wear resistance and better vibration damping than steel.

Construction - crushing, grading and wear components etc.

Food & feed milling - grinding, mixing, pelletizing etc.


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COMPARISON

ADI

Low machining cost.

Low heat treating cost.

Typically an ADI componentconsumes 50% less energythan a steel casting, andnearly 80% less energy than asteel forging.

ADI exhibits excellentcombination of strength andductility due to a combinationof ferrite and retainedaustenite after austempering.

Steel

High machining cost.

High heat treating cost.

Steel castings are highenergy intensive castings.

Steels when subjected toaustempering result in theformation of ferrite and

carbide resulting in lowerstrength and ductility whencompared to ADI.


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Experimentations To be Conducted

1) Charpy Impact test(notched & un-notched).

2) Micro Hardness test.


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Composition

Grade used:- 600-3

Tensile strength:- 600Mpa; Elongation:-3% .

Carbon:- 3.8-3.95%

Silicon:- 2.6%

Manganese:- 0.8%

Sulphur:- 0.002%

Phosphorus:- 0.012%

Magnesium:- 0.045%


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Specifications

Permanent Mould


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Methodology that will be followed

During 7th SEMESTER:

1)Problem formulation.2)Literature survey.

3)Production of castings.

4)Sample preparation.


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