Journal of Minerals and Materials Characterization and Engineering, 2012, 11, 1108-1112
Published Online November 2012 (
Effect of Titanium Addition on Behavior of
Medium Carbon Steel
Hoda S. El-Faramawy, Saeed N. Ghali*, Mamdouh M. Eissa
Steel Technology Department, Central Metallurgical R & D Institute (CMRDI), Cairo, Egypt
Email: *
Received July 10, 2012; revised August 15, 2012; accepted August 31, 2012
This work aims at investigating the influence of titanium addition on behavior of medium carbon steel. Three types of
medium carbon steel with different titanium content and one reference steel titanium free were produced in 100 kg in-
duction furnace. Titanium addition was increased up to 0.230%. The produced steels were forged at start temperature
1150˚C. Forging process was finished at temperatures 900˚C, 975˚C, and 1050˚C. Microstructure examination and
hardness measurement were carried out for forged steels. Mechanical properties and impact measurements were carried
out for quenched tempered steels. Ti addition was found to have significant influence on refinement of grains and in-
crease of ferrite/pearlite ratio. It was also, observed that grain size decreases as finishing temperature of forging process
decreases. Both Ti addition and lowering finishing forging temperature have positive effect on hardness. In addition,
results indicated that addition of titanium has significan t effect on the mechanical properties and toughness.
Keywords: Titanium; Refinement; Ferrite; Pearlite; Forging
1. Introduction
Mechanical properties of steels are strongly connected to
their microstructure obtained after heat treatments that are
generally performed in order to achieve a good hardness
and/or tensile strength with sufficient ductility [1].
Microalloyed steels have been developed for many
years and are widely used in modern industry. It is well
known that microalloyed high-strength low-alloy steels
are essentially carbon low-alloy steels that contain small
additions of alloying elements such as Nb, V, or Ti [2-6].
These elements act as solution atoms or precipitation to
suppress the recrystallization and grain growth of auste-
nite. Microalloying of carbon steels is widely used in
practice. At the same time, little attention has been given
to medium carbon steels containing vanadium, niobium
and titanium.
The obtained fine grain microstructure can enhance the
mechanical properties of steels obviously. In addition,
multimicroalloying can lead to the formation of carbide
and nitride particles which can further influence on the
mechanical properties of steels [7-10].
Due to the high price of niobium and vanadium, the
development of titanium microallo yed steels seems to be
attracted and get more attention recently.
Steel alloyed with titanium alone esp ecially the forma-
tion mechanism of TiC precipitation during different
processes and its effect are seldom studied in carbon
This work aims at investigating the influence of tita-
nium additions in medium carbon steels on mechanical
properties and also investigation of the effect of finishing
forging temperatures on grain refinem ents.
2. Experimental
Four steels with different titanium contents were melted
in induction furnace of capacity 100 kg and cast in sand
mold. Complete chemical analysis has been carried out
for all cast steels. Ingots with diameter 90 mm were hot
forged to about 40 mm square. The ingots were reheated
up to 1200˚C and hold to 30 min then start forging.
Starting forging temperature was 1150˚C while forging
process was ended at temperatures 900˚C, 975˚C, and
1050˚C for the four steels. Microstructure examination
and hardness measurements were carried out after for-
ging process. Ferrite/pearlite ratios were measured using
software Paxit program for forged steels. The forged bars
—which ended at 975˚C—were reheated up to 960˚C for
1 hour and water-coo led followed by tempering at 260˚C
for 30 min. The mechanical properties were measured for
tempered steels. The standard V-notch Charpy specimens
samples (10 mm × 10 mm × 55 mm, notch depth 2 mm)
was prepared to investigate the influence of the titanium
addition on impact toughness at 25˚C for tempered steels.
*Corresponding author.
Copyright © 2012 SciRes. JMMCE
3. Results
The melted steels have the chemical composition given
in Table 1. The microstructure examination of forged
steels at finishing temperatures 900˚C, 975˚C, and 1050˚C
is given in Figures 1-3 respectively.
It is clear that the grain size decreases as titanium con-
tent increases at finished forging temperature 900˚C as
illustrated in Figure 1. This can be attributed to the pre-
sence of titanium forming titanium carbides and/or tita-
nium nitrides on the austenite grains th at retard the grains
growth and hence grain of ferrite decrease. The same re-
sults observed at finishing forging temperatures 975˚C
and 1050˚C as shown in Figures 2 and 3. However, it
was observed that for the same steel, the grain size in-
crease by increasing the finishing forging temperature.
This can be due to the grain growth of austenite phase
during forging process and hence the ferrite and pearlite
grain size increase. Also, it may be due to the solubility
of titanium in austenitic phase increase as temperature
increases leading to decrease of TiC formation which
suppress the growth of austenitic grains.
The microstructure examination show that the fer-
rite/pearlite ratio increases by increasing titanium content.
This can be attributed to the formation of titanium car-
bides and consequently the free carbon is decreased
leading to the increase of ferrite/pearlite ratio.
Table 1. Chemical composition of melted steels.
Chemical composition (%)
Type C Si Mn P S Cr Ti
T0 0.301 0.108 1.13 0.040 0.030 0.4010.0015
T1 0.277 0.083 1.01 0.030 0.013 0.4040.0485
T2 0.275 0.104 1.04 0.033 0.019 0.4140.0997
T3 0.296 0.110 1.02 0.034 0.015 0.4090.2300
(a) (b)
(c) (d)
Figure 1. Microstructure of forged steels at finishing forg-
ing temperature 900˚C ((a) reference steel 0.0015%Ti, (b)
0.0485%Ti, (c) 0.0997%Ti, (d) 0.230%Ti)—X400.
However the finished forging temperature has little in-
fluence on the ferrite/pearlite ratios as illustrated in Ta -
ble 2.
It is clear fromTable 2 that ferrite percentage increases
from 10% to 12% as titanium content increases from
0.0015% to 0.2300%. While, th ere is little change in fer-
rite/pearlite ratio that results from finishing temperatures
of forging.
(a) (b)
(c) (d)
Figure 2. Microstructure of forged steels at finishing forging
temperature 975˚C ((a) reference steel (b) 0.0485%Ti, (c)
0.0997%Ti, (d) 0.230%Ti)—X400.
(a) (b)
(c) (d)
Figure 3. Microstructure of forged steels at finishing forg-
ing temperature 1050˚C ((a) reference steel (b) 0.0485%Ti,
(c) 0.0997%Ti, (d) 0.230%Ti)—X400.
Table 2. Show ferrite percentage of different Ti steel grades
at different finishing forging temperature.
Ferrite (%) at temperature (˚C)
Type 900 975 1050
Ti 0 68.28 65.02 63.13
Ti 1 69.46 70.94 69.12
Ti 2 73.53 71.78 70.01
Ti 3 78.21 76.95 75.12
Copyright © 2012 SciRes. JMMCE
The results show that the hardness increases by in-
creasing titanium content for each finishing forging tem-
peratures and increases by decreasing the finishing of
forging temperature as illustrated in Figure 4. Theref ore,
it is clear that the main controlling parameter for hard-
ness is the grain refinement.
Titanium content has great influence on mechanical
properties of steels, where it was noticed that the yield
and ultimate tensile strength increase by increasing tita-
nium content but elongation decreases as given in Figure
5. This can be attributed to the effect of grain refinement
of titanium.
Impact toughness is of importance for the evaluation
of the resistance capability of steel against the crack ini-
tiation and rupture. In general, it is of significant evi-
dences that the additio n of low alloy element (such as V,
Ti, and Ni , etc.) [11-12].
Titanium is used to retard grain growth and thus im-
prove toughness as it is clear from Figure 6.
Ti Content, %
0.00 0.05 0.10 0.15 0.20 0.25
Hardness, HV
900 oC
975 oC
1050 oC
Figure 4. Variation of hardness with titanium content at
different finishing forging temperatures.
Figure 5. Yield, ultimate tensile strength and elongation of
tempered steels with different titanium content.
The relation between the solubility products of car-
bides and nitrides as a fun ction of temperature illustrated
by Aronsson [13] is given in Figure 7. From this figure,
it is clear that the solubility product of TiC in austenitic
phase increases by increasing temperature from 770˚C to
From the results given in this figure the solubility of
titanium at this temperature range can be calculated and
is given in Table 3. From this table, it is clear that the
solubility of titanium increases by increasing temperature.
Consequently, TiC will decreases by increasing tem-
perature in the austenitic phase. As, there is a direct ef-
fect of TiC on the formed ferrite grain size, therefore by
decreasing temperature the ferrite grain size decreases.
The actual atomic mole fraction of Ti and its solubility
product of four types of steels is given in Table 4.
Ti content, %
0.00 0.05 0.10 0.15 0.20 0.25
Impact Energy, J
Figure 6. Impact energy of tempered steels at different tita-
nium content.
Figure 7. Solubility products of carbides and nitrides in
austenite as a function of temperature [13].
Copyright © 2012 SciRes. JMMCE
Table 3. The predicted solubility and solubility product of
Temp K 10000/T(K) Intercept mic
TiC with temperature according to Aronsson [13].
Solubility Solubility (S) Ato
product (S2) (mole fraction) %
1173 8.525149 2.8807 0.317188 0.563194
1248 8.012821 2.8807 0.471245 0.686473
1323 7.558579 2.8807 0.607835 0.779638
1073 9.319664 2.8807 0.078277 0.27978
1053 9.496676 2.8807 0.025049 0.15827
1044 9.578544 2.8807 0.000432 0.02078
1043 9.587728 2.8807 –0.00233 -
able 4. Actual solubility and solubility product of investi-
Type Ti mole Fraction Solubility product
gated steels.
Ti 0 0.0017 2.972E-06
Ti 1 0.0559 3.124E-03
Ti 2 0.1148 1.318E-02
Ti 3 0.2644 6.992E-02
Figure 7 and Table 3 show that the formation of TiC
the grain growth is re-
4. Conclusions
nium has great influence on grain
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