Presented by

Suresh Beera

12ETMM11

M.Tech/Ph.D

Materials Engineering

SEST, UoH

OXIDE DISPERSION STRENGTHENED

AUSTENITIC STAINLESS STEEL

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CONTENTS

Introduction to Stainless steels

Austenitic stainless steels

Oxide dispersion strengthening

ODS procedure

Comparisons with non ODS steels

Microstructure of ODS steel

applications

Advantages & disadvantages

Summary

References

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• Add Chromium to steel

• Above 13%, it precipitates

at the surface,

• Forms a Cr2O3 layer

Which doesn’t corrode.

•Martensitic (Heat Treated)

•Duplex (Mo and Ni)

•Ferrite (with Mo)

•Austenitic (with Ni, Mn)

Stainless Steel1

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AUSTENITIC STAINLESS STEELS when

compare to a typical carbon steel.

•high ductility,

•low yield stress

•relatively high ultimate tensile strength

•good corrosion resistance,

A carbon steel on cooling transforms from

Austenite to a mixture of ferrite and

cementite.

type 304 typically contain 18Cr and 8Ni

wt% (18/8 stainless) type 316 which

contains up to 3 wt% Mo, offers an

improved general and pitting corrosion

resistance,

They contain a maximum of 0.15% carbon,

a minimum of 16% chromium and sufficient

nickel and/or manganese to retain an

austenitic structure at all temperatures

from the cryogenic region to the melting

point of the alloy

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What Is An Oxide Dispersion Strengthened (ODS)

Alloy?

Oxide dispersion strengthened alloys (ODS alloys) typically

consist of a high temperature metal matrix - such as iron

aluminide, iron chromium, iron-chromium-aluminium, nickel

chromium or nickel aluminide - with small (5-50nm) oxide

particles of alumina (Al2O3) or yttria (Y2O3) dispersed within

it.

Iron-based and nickel-based oxide dispersion strengthened

alloys exhibit good corrosion resistance and mechanical

properties at elevated temperatures.

These alloys also show excellent creep resistance, and

partly from the very large elongated grain structure

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Composition (wt%)

Name Ni Fe Cr Al Ti C Yttrium

Oxide

INCONEL

MA754

78 1.0 20 0.3 0.5 0.05 0.6

INCOLOY

MA956

- 74 20 4.5 0.5 0.05 0.5

The composition of two commercially-available oxide

dispersion strengthened (ODS) alloys (one iron-based,

the other nickel-based) 10

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HOW ARE OXIDE DISPERSION STRENGTHENED

(ODS) ALLOYS PRODUCED?

yttria

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A Comparison Of Commercial ODS

Steels & ferritic/martensitic steels

A comparison of the yield stress

as a function of test temperature

for the three commercial ODS

steels and the non-ODS

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A comparison of the ultimate tensile

strength as a function of test temperature

for the three commercial ODS steels and

the non-ODS

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MICRO STRUCTURE OF STAINLESS STEEL 316L &

MECHANICAL ALLOYED 316L

SEM Images of (a) AISI 316L Stainless Steel, (b) Ti,

a b

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(d) MA Powders Composed of 99.4

wt% AISI 316L Stainless Steel,

0.3 wt% Ti ,

0.3 wt% Y2O3

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(c) Y2O3

Applications

0xide dispersion strengthened alloys (ODS)

are used for high temperature turbine blades

and heat exchanger tubing.Alloys of nickel

are the most common but work is being done

on iron aluminum alloys.

ODS steels are used in nuclear

applications.

ODS materials are used on space crafts as

a layer designed to protect the vehicle

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ADVANTAGES:

Can be machined, brazed, formed, cut with available

processes.

Develops a protective oxide layer that is self-healing.

Allows the design of thin-walled structures (sandwich).

Resistant to harsh weather conditions in the troposphere

Low maintenance cost.

DISADVANTAGES:

It has a higher expansion coefficient than other materials,

causing higher thermal stresses.

Lower maximum allowable temperature.

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Summary

ODS steels can by produced by mechanical alloying process,

hot isostatic pressing, and rolling.

ODS austenitic stainless steel , exhibit good corrosion

resistance, creep resistance and mechanical properties at

elevated temperatures

Yield strength and tensile strength of ODS Steels is higher

than ferritic/martensitic steels

Changes in Micro structure of Mechanical Alloying Stainless

Steel 316L was observed

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Elements of metallurgy and engineering alloys f.C.

Campbell, editor, p 573.148,441-445

F.C. Campbell, manuf acturin g technology for aerospace

structu ral mat erials, elsevier scientific, 2006

Oxide dispersion-strengthened steels: a comparison of

experimental and commercial steels―r. L. Klueh, j. P.

Shingledecker, r. W. Swindeman, and d. T. Hoelzer (oak ridge

national laboratory)

Oxide dispersion strengthened steels: a comparison of

microstructure features of some commercial steels with

Applying of doppler broadening spectroscopy

J. Veterníková, s. Kilpeläine, v. Slugen, f. Tuomisto

REFERENCES

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THANK YOU

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