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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)

782

Analysis of Abrasive Wear Characterization and its

Correlation with Structure for Low and Medium

Carbon Steels

Sachin Kumar1, Abhishek Jain

2 , Pramod Singh

3

1Student, Master of Technology, Department of Mechanical Engineering, BUIT, Barkatullah University, Bhopal. 2Asst. Professor, Department of Mechanical Engineering, BUIT, Barkatullah University, Bhopal, M.P.,INDIA.

3Deputy Manager, Bharat Heavy Electricals Limited, Bhopal, M.P.,INDIA.

Abstract– In most of the engineering applications, such as

mining, metallurgy, agriculture; equipments are failed by

the abrasive wear. The data as obtained form ministry of

Research and Technology indicates that the percentage cost

of abrasive wear in federal republic of German in

metallurgy industry is 40%, mining industry 30%,

agriculture 20% and production engineering 10%, and so

the material selection is largely controlled by adequate

selection of material and cost effectiveness.

The most common material being used at present

in India in metallurgical mining and agricultural industries

is a plain carbon steel. Particularly mild steel is widely used

in agricultural agro machinery industries for the fabrication

of agricultural equipment and critical parts, and therefore

which wears fast when subjected to high load and abrasive

conditions. The present work has been devoted to access the

suitability of adequate material properties and structure for

agricultural industries. The En 8 is a plain medium carbon

steel, En 19 and En 24 is a medium carbon low alloy steels

containing molybdenum and chromium in different amount

(up to 5% in total) . These steels are cost effective and easily

available in local markets in all shapes and dimensions.

Moreover their properties can be improved by simple heat

treatment.

The selected steels were heat treated and their

mechanical and Tribological properties have been accessed

for their suitability for agro machinery industries. The

Tribological properties have been quantitatively estimated

by three body abrasion test set-up which is Flex make as

per standard specifications of American society of testing

materials (ASTM), where the wear caused by abrasive

trapped between the two moving surfaces.

Keywords: Correlation, En-8, En-19, En-24, Alloy steels,

Properties, Wear analysis.

(I) INTRODUCTION

The present work has been devoted to access the

suitability of adequate material properties and structure

for agricultural industries. The En 8 is a plain medium

carbon steel, En 19 and En 24 is a medium carbon low

alloy steels containing molybdenum and chromium in

different amount (up to 5% in total) . These steels are cost

effective and easily available in local markets in all

shapes and dimensions. Moreover their properties can be

improved by simple heat treatment.

A variety of produced vehicles decides about the

necessity of manufacturing weldable plates and sheets,

characterized by the various tensile strength, formability

and work hardening depending on the structure [1]. The

selected steels were heat treated and their mechanical and

Tribological properties have been accessed for their

suitability for agro machinery industries. The Tribological

properties have been quantitatively estimated by three

body abrasion test set-up which is Flex make as per

standard specifications of American society of testing

materials (ASTM), where the wear caused by abrasive

trapped between the two moving surfaces.

(II) OBJECTIVE

The major objective in the present work is to access a

suitable treatment for the better abrasion resistant material

amongst the three selected steels for tillage applications

in agro machinery industry.



783

(III) MATERIAL SELECTION

Two basic steel compositions, both suitable for wind

tower applications, were selected for this investigation.

One is a low-carbon grade (0.06% C) with an addition of

about 0.03% Nb. The other is a medium-carbon grade

(0.15%C) with an addition of about 0.02% Nb. [2]

Several requirements must always be studied

when selecting the material from which to make a

particular component, and the final choice usually

involves a compromise. These requirements can be

broadly classified as :

Service requirements

Fabrication requirements

Economic requirements

ON THE BASIS OF SERVICE REQUIREMENTS

In order that a component be successful in service, it must

be of suitable strength, hardness, toughness, elasticity,

rigidity, etc., and its must be of a suitable weight. In

addition to these basic requirements, certain other

properties may also be required, such as suitable

electrical, magnetic or thermal properties, heat resistance,

and creep or fatigue resistance. Corrosion resistance must

usually be as high as possible; alternatively, the material

must respond to corrosion resistance treatment.

Even at this stage a compromise is almost always

necessary, such as a suitable strength/weight ratio, an

acceptable life at high temperature, or an acceptable

degree of corrosion resistance.

ON THE BASIS OF FABRICATION

REQUIREMENTS

It is convenient to classify materials as (a) casting'

materials, and (b) wrought materials. Casting involves

heating the material to make it molten and then pouring it

into a mould so that it assumes the shape of the

impression and retains that shape upon solidification.

Wrought materials are suitable for working; working

involves the manipulation of the material when it is in the

solid state.

Few materials are equally suitable for both

casting and working and very few materials are equally

amenable to all variations of casting or working. It is

necessary to consider the duty and the shape of the

component, and the quantity required and then to select a

materials with the required properties and which will be

suitable for the fabrication methods to be used; the

component must then be designed to suit the method

selected.

The ease with which a material can be machined,

and the quality of the finish so obtained is usually very

important, as is the suitability of the material for joining

by welding brazing, or soldering. As already stated, the

properties of some alloys can be altered by heat

treatment, but in some cases this treatment is lengthy, and

may thus make such materials unsuitable.

ON THE BASIS OF AVAILAIBILITY OF

MATERIALS

Engineering materials can be classified as (a) metallic

materials, and (b) non metallic materials. Although

metallic materials are the main ones used in engineering,

the non-metallic materials, which include the plastics,

rubber, and wood, are of special importance. The metallic

materials are sub-divided into two groups; these are the

ferrous alloys, and the non-ferrous metals and alloys. The

ferrous alloys contain iron and carbon, to which may be

added other elements to confer special properties. The

non-ferrous metals are all metals other than iron and its

alloy but the non-ferrous alloys may include small

amounts of iron. Quantitative image analysis using a

point counting method was conducted using five SEM

images for each sample. [3]

(IV) TRANSFORMATIONS

Fig. 4.1 Iron-Cementite Phase Diagram



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HYPOEUTECTOID STEELS

There are solid state transformations in these steels. They

are the transformation of gamma iron to alpha iron and

the decomposition of austenite. The limiting composition

for getting pearlite is 0.02,5 percent carbon. With carbon

content less than this amount, no pearlite will be formed.

The alloy will content only ferrite grains.

Steels containing carbon between 0.025 percent

to 0.8 percent would contain varying amount of ferrite

and pearlite and their relative proportions depend on

carbon content.

Austenite —» Ferrite + Cementite

(0.8 C) (0.025 C) (6.67 C)

Pearlite

Fig. 4.2 – TTT diagram of hypoeutectoid steels

HYPEREUTECTOID STEEL

Let us consider a steel of composition X3 (Fig. 4.1). As

the alloy is cooled from T6°C to T7°C, no phase change

occurs. However, at or just below T7°C, cementite (Fe3C)

begin to separate out. At T8°C, the composition of Y is

Y9, and that of cementite 6.67 percent carbon. On further

cooling, the entire amount of austenite will transform to

pearlite. Hence, the final microstructure consists of

pearlite and proeutectoid cementite.

Fig.4.3 – TTT diagram of hypereutectoid steels

EUTECTOID STEEL

Let us consider a steel containing 0.8 percent carbon (X4

in fig. 4.1). One cooling at eutectoid point S (723°C), all

austenite will transform into 100 percent pearlite. So, the

microsturcture at room temperature will reveal alternate

layers of ferrite and cementite, called pearlite.

Fig. 4.4 – TTT diagram of eutectoid steels



785

(V) EXPERIMENTAL SETUP

1. HEAT TREATMENT FURNACE

Make I -Pyromasters furnaces, Madras -49

Furnace Rating -3 KW, 230 Volts

Max Temp. -12000C

Make II -Threlek, Bangalore India

2. UNIVERSAL TESTING MACHINE

Model UH -200 A

Capacity -200 100 40 20 10 4 tf

Working Voltage-+10% Conditions

Warm up -15 min

Temp -5 - 40°C

Make -Shimadzu Corporation, Japan

(VI) PROCEDURE ADOPTED

Following is the step by step formulization of the problem

-

Composition analysis for carbon, silicon ,

manganese, chromium, molybdenum etc. of the

selected En 8, En 19 and En 24 steels

Preparation of tensile, abrasive, impact and

metallogrphy samples of standard specifications.

Heat treatment of the above selected steel

specimens, hardened and tempered at three

temperatures viz. 250, 400 and 600°C.

Abrasion characterization using three body

rubber wheel abrasion test set-up for the total 32

minutes test run, at the interval of 2 min. each

test run, at 5 and 11 lb. abrasion loads.

The characterization of mechanical properties

such as tensile strength and elongation using

universal testing machine of 200 tonnes

capacity, and hardness using Vickers hardness

testing machine. The impact strength was carried

out using charpy impact testing machine.

Microstructural study was done using scanning

electron microscope.

The comparative study by correlating the

structure and properties of the selected heat

treated alloys for their best suitability against

abrasive wear.

(VII) RESULTS

Graphs of percentage elongation/s hardness from varying

in different temperature grade steel as well as graph

between impact strength v/s volume loss have been

shown in fig. 7.1.

Fig. 7.1 Graphical representations and comparisons

7.1 En- 8 Steel

The mechanical properties, such as tensile strength found

decreased from 673 N/mm2 to 445 N/mm

2 with increase

in tempering temperatures from 250°C to 600°C.

Similarly the hardness also decreased from 541 to 228

HV with increase in tempering temperatures . (Table 7.1)

The percentage elongation, however, increased with

increase in tempering temperatures and the reverse trend

was observed for impact strength where the strength

decreased from 0.015 to 0.012 N mm with increase in

tempering temperatures.



786

The decrease in tensile strength was due to increase in

ductility of the material found with increase in tempering

temperatures, and therefore, the impact strength and

hardness decreases with increased in temperature; further,

the hardened structure observed as martensite and

retained austenite, which is converted into tempered

martensite with increase in tempering temperature from

250 to 600°C, and therefore, decrease in tensile strength

and hardness was observed. Corresponding decrease in

impact strength and percentage elongation were observed.

Steel Tempering

Temp.

CC)

Max. Wear (32 min

test run) Vol. loss (10 -

6 m3)

Hardne

ss (Hv)

Tensile strength

N/mm2

(Ton/inch2)

% E Impact strength

N-mm (ft. lb)

51b

(22.24 N)

111b

(48.928

N)

2 50 0 . 0 7 76 9 0 . 1 0 37 3 4 5 41 6 73 . 12 ( 4 4 . 2 7 ) 1 6 . 9 2 2 84 7 6 ( 2 1 )

En 8 4 00 0 . 1 0 34 8 0 . 1 7 44 9 3 81 5 47 . 68 ( 3 6 . 0 2 ) 1 8 . 7 3 2 62 1 1 ( 1 9 . 3 3 )

6 00 0 . 1 3 62 5 9 0 . 1 9 80 0 5 2 28 4 45 . 35 ( 2 9 . 2 9 ) 2 0 . 9 7 2 21 4 3 ( 1 6 . 3 3 )

2 50 0 . 0 7 39 0 5 0 . 1 5 68 0 5 5 25 1 27 7 . 3 7 ( 84 . 01 ) 1 1 . 3 8 1 40 0 7 ( 1 0 . 3 3 )

En 19 4 00 0 . 0 9 25 3 6 0 . 1 7 70 3 9 4 34 1 16 7 . 4 3 ( 76 . 78 ) 1 2 . 9 0 1 62 7 2 ( 1 2 )

6 00 0 . 1 1 82 9 6 0 . 1 9 32 5 6 3 28 9 57 . 30 ( 6 2 . 9 6 ) 1 7 . 1 7 3 02 7 9 ( 2 2 . 3 3 )

2 50 0 . 0 7 70 5 4 0 . ! 69 2 ? 4 5 04 1 59 5 . 1 5 ( 10 4 . 9 1 )

1 1 . 7 4 1 35 6 0 ( 1 0 )

En 24 4 00 0 . 1 0 26 0 5 0 . 1 7 80 1 1 4 38 1 40 2 . 5 0 ( 92 . 24 ) 1 4 . 1 9 2 25 9 1 ( 1 6 . 6 6 )

6 00 0 . 1 2 35 8 6 0 . 1 9 96 9 7 2 95 1 01 4 . 3 2 ( 66 . 71 )

1 6 . 3 2 2 93 7 1 ( 2 1 . 6 6 )

Table 7.1 - Wear properties of En 8, En 19, and En 24 steels (typical values)

'K' (10-6mm

3/Nm)

Steel Tempering Temp. Abrasion load

51b 11 lb

250 556.96 338.031

En 8 400 741.849 568.600

600 976.842 645.227

250 529.825 510.971

En 19 400 663.391 576.906

600 848.065 629.751

250 552.400 551.440

En 24 400 735.576 580.073

600 885.989 650.740

Table 7.2 - Coefficient of Abrasion 'K' (10 6 mm

3/ Nm) of the selected steels (Tentative life estimation)



787

Fig 7.1 SEM Photographs of En-8 steel tempered at 250 oC, 400

oC and 600 oC. (Couresy- RRL-AMPRI,Bhopal)

7.2 En 19 Steel

Mechanical properties of En 19 steel were also

determined as done for En 8 steel at three tempering

temperatures viz. 250, 400 and 600°C and the tribological

properties using similar abrasion test set up as for En 8

steel was used at two loads. The mechanical properties

such as tensile strength found 1277 N/mm2 for the steel

tempered at 250°C and 1167 N/mm2 and 957 N/mm

2 at

400 and 600°C tempering temperatures respectively.

(Table 7.1) The hardness values as found were 525 Hv for

the hardened and tempered at 250°C steel and decreased

with increase in temperature at 400 and 600UC was 434

and 328 Hv respectively. Similarly elongation (ductility)

and impact strength increase with increase in the

tempering temperatures (Table 7.1).

The decrease in tensile strength and hardness were due to

more and more conversion of retained austenite into

tempered martensite with increase in tempering

temperatures. However, the ductility (% elongation) and

the impact strength improved with increase in tempering

temperatures because of tempered martensite structure.

Fig 7.2 SEM Photographs of En-19 steel tempered at 250 oC,

400 oC and 600 oC. (Couresy- RRL-AMPRI,Bhopal)

7.3 En 24 Steel

Tensile strength of heat treated En 24 steel fond better

than En 8 and En 19, and, therefore, the toughness of En

24 which is the combined effect of hardness, strength and

elongation found better than En 19 and En 8 steel.

(Table 7.1)



788

The tensile strength as observed about 1600 N/mm2 at

250°C and 1400 and 1000 N/mm2 at tempering

temperatures 400 and 600°C respectively. The hardness

found 504 438 and 295 Hv at three tempering

temperatures viz. 250, 400 and 600°C respectively.

(Table 7.1)

The hardness and tensile strength found decreased with

increase in tempering temperatures because of strength of

tempered martensitic structure.

The elongation and impact strength found increased with

increase in tempering temperatures.

From readings and graphs, it is clear that the

precipitations of carbides at 600°C tempering

temperature. As the carbide particles are hard particles,

however the effect of hardness of the material may only

be effective when the particles are coherent with the

matrix.

Fig 7.3 SEM Photographs of En-24 steel tempered at 250 oC,

400 oC and 600 oC. (Couresy- RRL-AMPRI,Bhopal)



789

(VIII) CONCLUSION

The tensile strength values of En 24 steel found

decreased sharply compared to En 8 and En 19

steels on increases of tempering temperatures.

The impact strength values of En 8 steel found

decreased as tempering temperatures increased,

others i.e. En 19 and En 24 having ascending

values.

The hardness values found decreasing on higher

tempering temperatures from 250 to 600°C.

The abrasive wear, volume loss found increased

on higher tempering temperatures 250, 400,

600°C and loads 5 lb and 11 lb.

At higher loads i.e. on 11 lb, load, En 8,

tempered at 250°C was found better compared to

others, inspite of its lower tensile strength.

Life expectancy of En 8, 250°C found highest in

all.

At high tempering temperatures and high impact

loads, En 19 tempered at 600°C may be

efficiently used inspite of its higher cost.

Phase morphology as observed in all steels

tempered at 250°C was tempered martensite.

At high tempering temperatures i.e. 600°C, some

incoherent carbide precipitations of chromium

and molybdenum were found in En 19 and En 24

steels, and so causes mechanical properties to

decreased.

En 24 steel tempered at 250°C, found best suited

against abrasive wear, cost and mechanical

properties wise. Further , it has got better

response against heat treatment and so the

properties can still be improved. It is cheaper

than En 19 steel and easily available in all the

forms of any dimensions.

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