Journal of Minerals and Materials Characterization and Engineering, 2013, 1, 24-28 Published Online January 2013 (
On the Comparison of Microstructure Characteristics and
Mechanical Properties of High Chromium White Iron with
the Hadfield Austenitic Manganese Steel
Johnson O. Agunsoye1*, Talabi S. Isaac2, Agbeleye A. Abiona1
1Department of Me t a l l urgical and Materials Engineering, University of Lagos, Lagos, Nigeria
2Department of Materials and Metallurgical Engineering, University of Ilorin, Ilorin, Nigeria
Email: *
Received October 7, 2012; revised November 15, 2012; accepted November 27, 2012
In this study, high chromium white iron (HC-Wi) alloy and the Hadfield steel were studied. The microstructure of this
high-chromium iron was studied using Metallurgical optical microscopy (OM) and compared to the Hadfield steel. The
hardness and unnotched charpy impact strength of the HC-Wi alloy and Hadfield steel were examined at ambient tem-
perature in the as-cast and heat-treated conditions. A pin-on-disc test at linear speed of 1.18 m/s and a 10 N normal load
was employed to evaluate the wear behavior of both steel samples. Microstructural results showed that varying the car-
bon level in HC-Wi alloys can affect the chromium carbide morphology and its distribution in the austenite matrix
which leads to considerable changes of the mechanical properties. Abrasion test sh owed that HC-Wi alloys have supe-
rior wear resistance, about three times of the Hadfield steel.
Keywords: High Chromium White Iron; Hadfield Steel; Microstructure; Wear
1. Introduction
When there was a challenge to develop steel which pos-
sesses two extreme properties at the same time, Sir Ro-
bert Hadfield invented Hadfield steel in 1882. The idea
was to have steel which is tough and at the same time
hard. This type of steel with its austenitic matrix has high
toughness, high ductility, and high work-hardability.
Majority of the cast Hadfield steel are excellent candi-
dates in variety of applications such as: earthmoving,
mining, railways, quarrying, dredging and drilling in the
oil/gas [1,2].
The global economic recession has continue to place
heavy burden on foundries world-wide and Nigeria in
particular to look for means of improving their produc-
tivity and higher products quality, as well as to strive to
achieve the optimum economy in wear industries; in the
past decade, the use of carbon steel ball in dry mill
grinding has been replaced with in situ ceramic-steel
composite synthesis technique to increase the life of the
wear parts. In this technique, hard ceramic forming ele-
ments are introduced to the molten steel as an alloying
element and a more thermodynamically stable reinforc-
ing phase will be fo rmed during solidification b y the nu-
cleation and growth mechanism in the parent matrix [3].
One of the most common ceramic reinforcing materials
being used in iron base alloys is carbides and among
them chromium carbide due to its high hardness of about
1020 - 1835 Hv [4], h ave prov ed to b e a un ique choice to
wear resistance of cast high chromium white iron with
martensitic microstructure [5,6]. However, less attention
has been paid to the research on Hardfield Austenitic
Mangane s e s teel.
In general terms, the high chro mium iron suitable for
wear r esi stin g a ppl icat ions fal l w ith in th e co mpo sit iona l
limits bounded by the austen itic ph ase field of the tern ary
liquidus surface of the iron, chromium, carbon diagr am.
Solidification takes place by a eutectic process The pro-
ducts of the eutectic reactio n are austenite and chromium
rich carbides of the (FeCr7)C3. For high chromium white
iron with a Cr concentration of some 18 - 20 wt%
(hypoeutectic composition), solidification starts with the
nucleation of dendritic primary austenite (γ), follo wed by
the formation of γ + M7C3 carbide and its morphology
have been well documented by several researchers [7].
The HC-Wi alloy has an austenitic matrix structure at
ambient temperature with chromium carbide dispersed
within the matrix. The wear resistance of this material is
achieved at the surface when the abrasive particle or im-
pact load transforms the unstable Austenite to martensite
by strain induced mechanism. This phenomenon of Aus-
*Corresponding author.
opyright © 2013 SciRes. JMMCE
tenite transformation to martensite causes increased sur-
face hardness and less wear rate loss. Carbon content
plays a significant role in chromium carbide formation
and its morphology as well as hardness, impact tough-
ness and wear resistance. In this study, the effect of car-
bon content on the microstructure, mechanical proper-
ties and wear characteristics of HC-Wi has been studied
and compared to the Hadfield steel.
2. Materials
HC-Wi and Hadfield Steel grade of materials were pro-
duced in Nigerian Foundries Limited (NFL), Otta, Nige-
ria using the charge makeup in Tables 1 and 2 respec-
tively. An Electric Induction Furnace of 500 kg neutral
lined was used for the melting operation and the sample
representative taken from the molten bath at 1550˚C d
and poured into a CO2 sand improvised moulds (11 × 11
× 200) mm. The charge makeup used in obtaining the
specification is tabulated below.
After the first heat from Ta ble 1, a sample representa-
tive was taken and casted. For subsequent batches, fine
granules of graphite were added in their various compo-
sitions of 1.6% C, 2.2% C, 2.7% C and 3.3% C respec-
tively to the molten bath and the temperature maintained
at 1520˚C - 1543˚C for 10 minutes to enable the graphite
granules dissolve adequately. This process was repeated
Table 1. Charge makeup for HC-Wi.
Elemental Contribution (%)
Raw Materials Mass (Kg) C Si Mn P S Cr
Returns 156.25 0.94 0.21 0.01 0.01 0.017.19
Steel Scraps 223.21 0.09 0.09 0.04 0.02 0.020.00
Fe-Cr 98.21 0.10 - - - - 17.68
Fe-Si 2.23 - 0.33 - - - -
Fe-Mn 4.46 0.07 - 0.58 - - -
Graphite 3.80 0.51 - - - - -
Total 500 1.55 0.63 0.63 0.03 0.03 24.87
Table 2. Charge makeup for Hadfield Steel.
Elemental Contribution (%)
Charge makeup
for Hadfield
SteelRaw Material
(Kg) C Si Mn P S Cr
Returns 187.83 0.410 0.190 4.760 0.005 - 0.570
Steel Scraps 234.80 0.095 0.120 0.120 - - -
Fe-Cr 7.04 0.001 - - - - 1.280
Fe-Si 2.00 - 0.300 - - - -
Fe-Mn 63.40 0.140 - 9.640 - - -
Graphite 4.93 0.66 - - - - -
Total 500 1.30 0.610 14.52 0.005 0.0001.850
for all incremental granules addition. To reduce the ten-
dency for oxidation, 1 Kg of Aluminum Briquette was
added to the melt. Besides, Hadfield steel melt was pre-
pared according to ASTM 128 C standard as presented in
Table 2.
The overall chemical composition obtained for the 2
heats and 5 batches is presented in Table 3.
A calibrated Hilger Analytical Direct Optical Emission
Polyvac Spectrometer E980 C with 20 analytical channe ls
was used for the analysis of the chemical composition of
the HC-Wi and Hadfield steel. Hadfield steel is difficult
to machine due to its work-hardening propensity. Hence,
a sample representative was taken from the Hadfield
steel molten bath and poured in to a (10.20 × 10.2 × 200)
mm preheated medium carbon steel mould so as to obtain
the required (10 × 10 × 50) mm bar for the impact test.
This technique was aimed at avoiding the need to ma-
chine the samples. To investigate the effect of the heat
treatment of Hadfield steel on the properties of HC-Wi,
halves of all the specimens with the size (10 × 10 × 50)
mm were solution annealed at 1050˚C for 30 minutes and
then water quenched.
2.1. Microstructure
For microstructural analysis, all the as-cast and heat-treat-
ed samples were cut from the bottom end, ground with
tehrapol-31, then polished using a colloidal suspension of
0.04 µm silicon dioxide and then etched in 100 ml alco-
hol and 3 ml HNO3 acid after polishing using Allegrol
with diamond suspension at the Metallographic Labora-
tory, Department of Mechanical Engineering of the Uni-
versity of Ot t a wa , Ca nada. A metallurgical optical m icro-
scopy was used to study the microstruc tures.
2.2. Mechanical Properties
Vickers micro hardness of tested samples was measured
using Duramin-1 microhardness tester struers. The re-
ported hardness values were the average of five meas-
urements. Charpy unnotched impact test was also carried
out on (10 × 10 × 50) mm standard Hadfield and HC-Wi
specimens at room temperature. In order to compare the
wear resistance of the developed HC-Wi alloys with
Hadfield steel, abrasive wear tests were conducted on all
Table 3. Chemical composition of the HC-Wi.
MaterialCMnSiCrP S Mo Ni AlFe
HC-Wi-11.550.630.6324.870.03 0.03 0.02 0.01 0.01Balance
HC-Wi-22.220.630.6224.600.03 0.03 0.01 0.01 0.01Balance
HC-Wi-32.730.590.6024.200.03 0.03 0.01 0.015 0.02Balance
HC-Wi-43.260.560.6023.600.03 0.03 0.01 0.01 0.02Balance
Steel 1.3014.520.611.850.01 0.00 - - 0.15Balance
Copyright © 2013 SciRes. JMMCE
cast sample in the as-cast and heat-treated conditions us-
ing a pin-on-disc wear machine as per ASTM G99-95
Standard. The disc used is En-32 steel hardened to 62
HRC, 200 mm track diameter and 12 mm thick with sur-
face roughness of 20 µm Ra. The sample with cross sec-
tion 10 mm × 10 mm was taken from the fracture impact
test and used for the wear test. Applied normal load on
all the samples was 10 N over a sliding distance of 70.8
m on a fresh 120 grit SiC abrasive paper. Before and
after each test, the sample was carefully cleaned with
acetone and weighed using an analytical balance with an
accuracy of 0.001 g. The relative wear resistance was
given by the weight loss of HC-Wi alloy samples related
to the weight loss of the heat-treated Hadfield steel sam-
ple. The reported values are the average of four test runs
on each composition material.
3. Results and Discussion
3.1. Microstructural Analysis
Figures 1(a)-(d) show the effect of carbon content on
the morphology and distribution of primary chromium
carbides in HC-Wi alloys in the as-cast condition. When
the high chromium molten alloy starts to solidify; chro-
mium carbide nucleation takes place and grows in the
mel t a n d crystalliz es as coarse primary chromium carbides
between the liquidus and solidus temperatures. It has
been observed from the data available from Table 3 and
Equation (1),
%Carbide12.33 %C0.55 %Cr15.2
(1) [8]
that as the carbon content of the HC-Wi increases, the
amount of chromium carbide increases (Table 4) and
primary chromium carbides change from the fairly round,
strip into spherical shape and they are distributed more
uniformly up to carbon content of 2.73 but further in-
crease in the carbon content decreases the homogeneity
of the chromium carbide distribution within the austenitic
matrix (Figures 1(b) and 1(c)).
In HC-Wi alloy, due to the presence of >20% Chro-
mium in the composition as one of the strongest carbide
forming elements in steel compared to iron or manganese
(very high affinity of chromium to absorb carbon), chro-
mium reacts with the dissolved carbon of the molten steel
resulting to the formation of chro mium carbide instead of
iron manganese carbide.
In as-cast Hadfield steels, austenite grain boundary
steel are surrounded by a continuous network of segre-
gated and brittle (FeMn)3C shown in Figure 3(a). Solu-
tion annealing between the temperature range of 1000˚C -
1050˚C dissolves these carbides in austenite and subse-
quently quenching in water prevents the formation M3C
in grain boundary as shown in Figure 3(b) [9].
In high chromium austenite steel, due to the presence
(a) (b)
(c) (d)
Figure 1. Optical micrograph of HC-Wi in the as-cast con-
dition. (a) HC-Wi-1 (b) HC-Wi-2 (c) HC-Wi-3 (d) HC-Wi-4.
Table 4. The amount of chromium carbide (Cr3C7, %) in
the as-cast conditions.
Sample HC-Wi-1HC-Wi-2 HC-Wi-3 HC-Wi-4
Volume of Cr7C317.59 25.70 31.77 37.98
(a) (b)
(c) (d)
Figure 2. Optical micrograph of HC-Wi in heat-treated condi-
tion. (a) HC-Wi-1 (b) HC-Wi-2 (c) HC-Wi-3 (d) HC-Wi-4.
(a) (b)
Figure 3. Optical micrograph of the hadfield steel (a) a s-cast
condition (b) heat-treated condition.
Copyright © 2013 SciRes. JMMCE
of more than 20% chromium, chromium is one of the
strongest carbides forming element in steel compared to
iron or manganese (chromium has high affinity for car-
bon), chromium reacts with the dissolved carbon in the
molten steel leading to the formation of a more stable
chromium carbides instead of iron manganese carbides.
When compar ed to Figure 3, iron manganese carbides in
HC-Wi samples virtually non-existence and form a con-
tinuous network of brittle phase around the austenite
3.2. Mechanical Properties
Initially measured values of Vickers hardness of all sam-
ples in as-cast and heat-treated conditions before the ab-
rasion test are presented in Figure 4. It shows that the
hardness of HC-Wi alloys is almost 69% higher than
Hadfield austenitic manganese steel due to the presence
of high percentage of extremely hard chromium carbide
Cr3C7 in the microstructure. Solution annealing has less
influence on the hardness changes of HC-Wi alloy com-
pared to Hadfield austenitic steel. Hadfield steels contain
some segregated hard grain boundary carbide of the form
Cr3C7 within the softer austenite matrix. This is clearly
responsible for the increase in overall hardness in the
as-cast conditions. Figure 4 also showed that austenite
matrix in HC-Wi alloys is more than twice the hardness
of the Hadfield steel (in both as-cast and heat-treated
This considerable increase in austenite hardness is re-
lated to the solution of carbon and ch romium elements in
iron lattice coupled with the precipitation of secondary
chromium carbide (Figures 1 and 2) in austenite which
strengthens the soft matrix.
Figure 5 shows Charpy unnotched impact toughness
of the materials. The main difference in impact energy
values before and after the heat treatment was observed
in the Hadfield steel and it is due to the disso lution of the
Har dn ess(Hv)
Figure 4. Vickers micro-hardness of as-cast and heat-treated
St ee l
ImpactToug hness(J)
He attreated
Figure 5. Impact toughness of HC-Wi alloys and Hadfield
brittle carbide, segregated along the austenite grain
boundaries in the as-cast condition (Figure 3(a)). These
brittle phases with lamellar/acicular morphology along
the boundaries cause stress to be built-up in the matrix,
leading to dislocation pile up, crack initiation, propaga-
tion and crack growth and subsequently low impact
toughness of the Hadfield steel in as-cast condition. For
HC-Wi alloys, chromium carbide morphology and its
distribution both influence significantly the impact en-
ergy. HC-Wi-1 composition with uniform distribution of
chromium carbide has the highest impact toughness,
while the HC-Wi-4 has the lowest impact toughness. As
the carbon content increases, the morphologies of the
chromium carbides in the matrix also change. The dis-
tribution of the chromium carbide influences the me-
chanical properties of the material.
3.3. Wear Resistance
The wear loss of HC-Wi alloys compared to the heat-
treated Hadfield steel in the as-cast and heat-treated con-
ditions are presented in Figure 6. The predominant wear
mechanism in the pin-on-disc abrasion test is micro cutt-
ing and surface hardness of the materials plays a signifi-
cant in determining the wear resistance. Hence, HC-Wi
alloys shows remarkab le higher wear resistance (3 times)
than Hadfield steel due to higher surface hardness caused
by the existence of hard carbide phase dispersed within
the austenite matrix. Despite the low surface hardness of
HC-Wi-3 compared to HC-Wi-4, the wear resistance of
HC-Wi-3 is superior and higher than HC-Wi-4 (Figure
6). This is because the carbide distribution in HC-Wi-4 is
heterogeneous (Figure 2(d)). Hence, that the distribu-
tions of the hard second phase carbide also affect the
wear resistance.
4. Conclusions
1) High chromium white iron alloy have superior wear
resistance compared to hadfield austenitic manganese steel
due to the presence of hard chromium carbide distributed
within the matrix of the microstructure.
Copyright © 2013 SciRes. JMMCE
Copyright © 2013 SciRes. JMMCE
He at treated
Figure 6. Weight loss of HC-Wi alloys and Hadfield steel.
2) The presence of chromium carbide lowers the im-
pact toughness of HC-Wi alloys compared to Hadfield
austenitic manganese steel.
3) The mechanical properties of HC-Wi alloys are af-
fected by the distribution of the hard second phase parti-
cles in the austenite.
4) For practical application where replacements of
worn-out mechanical components result to frequent plant
shutdown with associated high maintenance cost, the more
expensive HC-Wi alloys are recommended over the chea-
per Hadfield manganese steel.
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