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INFLUENCE OF CHROMIUM CONTENT ON MICROSTRUCTURE AND PROPERTIES OF HADFIELD STEEL

AUTHOR: NGUYEN DUONG NAM, PHAM MAI KHANH, LE THI CHIEU AND HOANG THI NGOC QUYEN

DEPARTERMENT OF MATERIALS AND ENGINEERING, HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY.

INSTRUCTOR: DR. TRAN DUC HUYSTUDENT: TRAN VAN HIEP

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CONTENTS

INTRODUCTION THE INFLUENCE OF CHROMIUM ON MICROSTRUCTURE AND PROPERTIES OF HADFIELD STEEL

EXPERIMENTAL RESULT AND DISCUSSION

CONCLUSION

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HISTORY

Hadfield – high manganese steel was found by Sir Robert Hadfield, a British metallurgist, in 1882.

He found it by put more Mn into molten metal with ratio Mn:C (10:1) The best mechanical properties with 1 - 1.4% C and 11 - 14% Mn He obtained a material has exceptional durability. Using in the construction of railroad rails and rock-crushing machinery.

1858-1940

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HADFIELD STEEL Characteristics of Hadfield steel:

- It is a work hardening steel and more impact and abrasion it gets the harder the surface becomes

- Steel stays ductile underneath - only surface layer hardens

- Low friction properties and non-magnetic Chemical composition:

Mechanical properties:

C Mn Si P S Cr Ni Fe

1.0-1.3 12.0-14.0 0.5-0.8 0.005 max

0.05 max

- - bal

YS (MPa)

UST(MPa)

EL(%)

Modulus(MPa)

Hardness (HV)

Impact (J.)

414 955 40 186x 200 112

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APPLICATIONS OF HADFIELD STEEL

Rails

Mechanic toolMatrix of MMCs

Wheel of tankMilling Hammer

Excavator Bucket

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APPLICATIONS

Note: Hadfield steel just has wear resistence very high, but in an other

condition, it is very weak because it can not form surface layer hadens. Example: when atomic sand, hadfield was be corrosion rapidly.

Although steel has low hardness after austenization (200HV), but it is so hard for cutting Just fabricate by casting.

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HADFIELD STEEL

Phase diagram of high manganese, 13% Mn

Microstructure

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EXPERIMENTAL WORK

Melting

Set 10.03%Cr

Set 21.91%Cr

Set 32.53% Cr

Heat Treatment EDS Cutting Micro-Mechanical

Properties

Wear TestImpact TestHardness

Optical Microscope SEM

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EXPERIMENTAL WORK

Set Fe C Si Mn Cr

1 83.4 0.80 1.10 13.70 0.03

2 82.9 1.13 0.78 12.80 1.91

3 81.6 0.85 1.13 12.90 2.53

Chemical composition

- After casting, forming a lost of carbide (Mn3C, Fe-Mn3C) at grain boundary britte- Reheating to 1050oC and hold in 2h, quenching in waterCarbide was be soluted into austenite. Just a litte carbide stays in grain boundary increse strength, toughness

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RESULT AND DISCUSSION

Before testing:-Set 1: Grain size after casting abt 100μm (coarse)

Austenite matrix-Set 2, 3: Grain size 40-50μm

Austenite matrix

Austenite, γ-Fe

Mn

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RESULT AND DISCUSSION

Following TCVN 312- 1:2007, impact 1000 times, load 100N/cm2

After Testing: Observed no martensite structure

Set 1: Austenite matrix, and a litter twins structureSet 2: Austenite matrix, but has more twins structure

with multi-direction and grain size is smaller ( ~30μm)

Set 3: Austenite matrix, carbides and twins less than set 2

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RESULT AND DISCUSSION

Hardness resultSample Set 1 Set 2 Set 3

No impact, load 169 192 195

Impact, load 200 219 225

Set 1 Set 2 Set 30

50

100

150

200

250

169192 195200

219 225

Hardness (HV)

No Impact Impact

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CONCLUSION

Two main point1. In work hardening of Hadfield steel, there is

no martensite transformation.That is the formation of twins and defect

2. With ~ 2% Cr, we get the best mechanical properties.

Microstructure

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FUTURE WORK

1. In my opinion, we need do more testing in different condition or combine 2,3 condition to reach accurate result.

2. In addition, we should be consider more abt the influence of elements such as V, Si, Ni,…

3. May be in the different of fabrication Hadfield steel process, we will get different result.

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REFERENCE

1. http://psrcentre.org/images/extraimages/4%20414052.pdf

2. http://www.steelmills.com/Manganese_Steel.html

3. http://file.scirp.org/Html/27241.html

4. http://www.oto-hui.com/threads/thep-austenit-mangan-cao-qua-khu-hien-tai-va-tuong-lai.8685/

5. https://nguyenkhanhks.wordpress.com/tag/thep/

6. https://sites.google.com/site/truongvanchinhvatlieucokhi/home/gang-va-thep-1/thep/thep-hop-kim-dac-biet/thep-co-tinh-chong-mai-mon-dac-biet-cao-duoi-tai-trong-va-dap

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