Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay
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Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay
Este es un artículo de acceso abierto distribuido bajo los términos de una licencia de uso y distribución CC BY-NC 4.0. Para ver
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Mechanical Characterization of Post weld quenched Al 6082-T6 TIG
welded Joints
Caracterización mecánica de uniones soldadas TIG Al 6082-T6
templadas después de la soldadura
Caracterização mecânica de juntas soldadas TIG Al 6082-T6
pós-soldagem temperada
Atif Shazad
1
, Muhammad Uzair
2
(*), Junaid Jadoon
3
, Muhammad Saleem Khan
4
Recibido: 27/09/2024 Aceptado: 26/01/2025
Summary. - This research aims to enhance the efficiency of weld joints through a cost-effective methodology.
Aluminium 6082-T6 is the chosen material due to its frequent use in applications that require intermediate strength
with low weight. Welding operations typically lead to a weakening of material strength by up to 50% due to the high
input heat. Therefore, the focus of this study is to improve the strength by employing quenching techniques with
different media, such as sand, water, and hydraulic oil. A comparative analysis of the mechanical properties is
performed based on the quenching of weld joints using these various media. Additionally, microstructure examination
is conducted to facilitate this comparative study. The mechanical properties investigated include hardness, tensile
strength, yield strength, and toughness, with the goal of understanding the impact of different quenching media. The
research reveals that water-cooled joints exhibit higher yield strength, while oil-cooled joints demonstrate superior
tensile strength compared to other joints. Furthermore, the ductility of oil-cooled joints is notably higher, as measured
by % elongation. Water cooling leads to noteworthy hardness in both the Weld Zone (WZ) and Heat-Affected Zone
(HAZ) due to rapid cooling. In contrast, the hardness of oil-cooled joints is not significantly different from that of
water-cooled welded joints. Regarding toughness, oil-cooled joints show greater impact energy in the HAZ compared
to those quenched with water, sand, and air. However, in the WZ, air-cooled joints exhibit superior impact energy,
which directly indicates better toughness properties. Therefore, oil-cooled joints display higher toughness in the HAZ,
while air-cooled joints are tougher in the WZ. Overall, the mechanical properties of oil-cooled joints are significantly
enhanced, leading to an improved weld efficiency from 55% to 72%.
Keywords: TIG welding; mechanical properties; Al 6082-T6; quenching media.
1
PhD Scholar, Department of Mechanical Engineering, NEDUET (Pakistan), atifshahzad2717@gmail.com,
ORCID iD: https://orcid.org/0000-0002-3277-7901
2
Associate Professor, Department of Mechanical Engineering, NEDUET (Pakistan), uzair@neduet.edu.pk,
ORCID iD: https://orcid.org/0000-0002-2033-6244
3
Student, Department of Mechanical Engineering, PIEAS (Pakistan), junaidjadoon2012@gmail.com,
ORCID iD: https://orcid.org/0000-0001-6217-1962
4
Student, Department of Metallurgy and Materials Engineering, NED University of Engineering and Technology (Pakistan),
saleemkhan.uet@gmail.com, ORCID iD: https://orcid.org/0009-0003-5547-6452
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 59
Resumen. - Esta investigación busca mejorar la eficiencia de las uniones soldadas mediante una metodología rentable.
El aluminio 6082-T6 es el material elegido debido a su uso frecuente en aplicaciones que requieren resistencia
intermedia con bajo peso. Las operaciones de soldadura suelen provocar una reducción de la resistencia del material
de hasta un 50 % debido al elevado calor de entrada. Por lo tanto, este estudio se centra en mejorar la resistencia
mediante técnicas de temple con diferentes medios, como arena, agua y aceite hidráulico. Se realiza un análisis
comparativo de las propiedades mecánicas basado en el temple de las uniones soldadas con estos diversos medios.
Además, se realiza un examen de la microestructura para facilitar este estudio comparativo. Las propiedades
mecánicas investigadas incluyen dureza, resistencia a la tracción, límite elástico y tenacidad, con el objetivo de
comprender el impacto de los diferentes medios de temple. La investigación revela que las uniones refrigeradas por
agua presentan un mayor límite elástico, mientras que las refrigeradas por aceite demuestran una resistencia a la
tracción superior en comparación con otras uniones. Además, la ductilidad de las uniones refrigeradas por aceite es
notablemente mayor, medida mediante el porcentaje de elongación. El enfriamiento por agua produce una dureza
notable tanto en la zona de soldadura (ZS) como en la zona afectada por el calor (ZAC) debido al rápido enfriamiento.
Por el contrario, la dureza de las uniones enfriadas con aceite no es significativamente diferente de la de las uniones
soldadas enfriadas con agua. Con respecto a la tenacidad, las uniones enfriadas con aceite muestran una mayor
energía de impacto en la ZAC en comparación con las templadas con agua, arena y aire. Sin embargo, en la ZS, las
uniones enfriadas con aire exhiben una energía de impacto superior, lo que indica directamente mejores propiedades
de tenacidad. Por lo tanto, las uniones enfriadas con aceite muestran una mayor tenacidad en la ZAC, mientras que
las uniones enfriadas con aire son más tenaces en la ZS. En general, las propiedades mecánicas de las uniones
enfriadas con aceite mejoran significativamente, lo que lleva a una mejora en la eficiencia de la soldadura del 55% al
72%.
Palabras clave: Soldadura TIG; propiedades mecánicas; Al 6082-T6; medios de enfriamiento.
Resumo. - Esta pesquisa visa aumentar a eficiência de juntas soldadas por meio de uma metodologia econômica. O
alumínio 6082-T6 é o material escolhido devido ao seu uso frequente em aplicações que exigem resistência
intermediária com baixo peso. As operações de soldagem normalmente levam a um enfraquecimento da resistência do
material em até 50% devido ao alto calor de entrada. Portanto, o foco deste estudo é melhorar a resistência
empregando técnicas de têmpera com diferentes meios, como areia, água e óleo hidráulico. Uma análise comparativa
das propriedades mecânicas é realizada com base na têmpera de juntas soldadas usando esses vários meios. Além
disso, o exame da microestrutura é realizado para facilitar este estudo comparativo. As propriedades mecânicas
investigadas incluem dureza, resistência à tração, resistência ao escoamento e tenacidade, com o objetivo de
compreender o impacto de diferentes meios de têmpera. A pesquisa revela que juntas resfriadas a água apresentam
maior resistência ao escoamento, enquanto juntas resfriadas a óleo demonstram resistência à tração superior em
comparação com outras juntas. Além disso, a ductilidade das juntas resfriadas a óleo é notavelmente maior, medida
pela % de alongamento. O resfriamento a água resulta em dureza notável tanto na Zona de Solda (ZS) quanto na Zona
Afetada pelo Calor (ZAC) devido ao resfriamento rápido. Em contraste, a dureza das juntas resfriadas a óleo não é
significativamente diferente daquela das juntas soldadas resfriadas a água. Em relação à tenacidade, as juntas
resfriadas a óleo apresentam maior energia de impacto na ZAC em comparação àquelas temperadas com água, areia
e ar. No entanto, na ZC, as juntas resfriadas a ar exibem energia de impacto superior, o que indica diretamente
melhores propriedades de tenacidade. Portanto, as juntas resfriadas a óleo apresentam maior tenacidade na ZAC,
enquanto as juntas resfriadas a ar são mais tenazes na ZC. No geral, as propriedades mecânicas das juntas resfriadas
a óleo são significativamente aprimoradas, levando a uma eficiência de soldagem aprimorada de 55% para 72%.
Palavras-chave: Soldagem TIG; propriedades mecânicas; Al 6082-T6; meios de têmpera.
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
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1. Introduction. - Aluminium alloys are widely used in numerous applications due to their excellent strength-to-weight
ratio. Among these alloys, Al 6082 is noted for its significant strength combined with a low weight. Additionally, this
alloy exhibits remarkable resistance to rust and possesses good reusability properties [1]. Its application is especially
prevalent in the automobile industry, where it is used in the manufacturing of suspension components. Al 6082 is
primarily composed of Aluminium (Al), Magnesium (Mg), and Silicon (Si). To further enhance its mechanical
properties such as tensile and yield strength, impact strength, and grain boundary size, Al 6082 undergoes heat
treatment [2]. A hot forging process is commonly utilized by many industries to produce intricate parts in a single
operation. However, this process results in a highly deformed microstructure with significant thermal and mechanical
stresses. As a consequence, post-forging heat treatment is often employed to alleviate such defects [3][4].
Joining Al 6082 through welding helps to reduce residual mechanical and thermal stresses to some extent. However,
a major drawback of welding is the reduction in joint strength. After welding, the tensile strength and hardness can be
reduced by up to 50%, necessitating post-weld heat treatments to enhance joint strength. Unfortunately, these post-
weld heat treatments can be expensive [5]. Forging is considered a cost-effective and efficient method for
manufacturing small-sized parts; however, for large-sized parts, forging becomes cumbersome and expensive [6]. As
a result, welding is commonly employed to join different parts and create giant structures. The choice of welding
parameters is known to significantly impact the performance of welded joints, with the type of welding technique
playing a crucial role [7]. Tungsten Inert Gas (TIG) welding is preferred in applications requiring concentrated heat,
while Shielded Metal Arc Welding (SMAW) is not suitable for such tasks due to its wider heat-affected zone (HAZ)
compared to TIG welding [8].
TIG welded joints of Al 6082 have been found to exhibit superior strength compared to Metal Inert Gas (MIG) welded
joints. This improvement in strength is attributed to the presence of equally sized grain boundaries after TIG welding,
resulting in a very fine spacing between adjacent grains [9]. Furthermore, the hardness of the joints has been shown to
be influenced by the speed of the tungsten electrode, with higher speeds contributing to the softening of the joint area.
The impact of subzero temperature conditions has been observed to strongly affect the mechanical properties of Al
6082, and thick plate coalescence using arc welding has led to the occurrence of various defects such as cracks and
pores [10]. These findings highlight the importance of selecting appropriate welding techniques and parameters to
ensure the desired mechanical properties and structural integrity in welded joints, especially when dealing with large-
sized structures.
A parametric study to evaluate key influencing factors in TIG welding of Aluminium alloys is considered very
essential. An increment in welding current has been found to negatively affect the tensile strength and hardness of the
welded joints. However, optimal results have been achieved with a welding current of 150A and a welding speed of
200 mm/min, leading to improved tensile strength and hardness properties [11]. The heat treatment of Al 6082-T6
alloy has produced a serious effect on hardness. Artificial aging at 175℃ has significantly enhanced the hardness,
whereas performing solution heat treatment before age hardening has led to a degradation in hardness. The
development of the Mg2Si phase during artificial aging has increased the brittleness of Al 6082, consequently
contributing to its increased hardness [12].
Exploration of input heat influence on the precipitation hardening of Al 6082 during TIG welding has affirmed that
the concentrated arc generated during TIG welding allows for directed heat flow to the fusion areas, quickly achieving
the desired fusion temperature. Additionally, TIG welding is considered a welding technique with minimal defects,
especially when compared to other fusion techniques. The distortions resulting from temperature distribution on
welded joints are known to be more severe in other fusion techniques than in TIG welding [13][14]. Severe residual
stresses due to non-uniform thermal loading are known to negatively impact the corrosion behaviour of aluminium
alloys. The elevated temperatures experienced during welding induce thermal stresses, leading to stress corrosion
cracking, precipitation, and subsequent pitting corrosion. These factors ultimately compromise the strength of welded
joints [15]. Moreover, the anodic and cathodic behaviour of aluminium alloy precipitates influence the corrosion
phenomenon. The research has demonstrated that magnesium dissolution exhibits an anodic behavior and contributes
to the enhanced occurrence of pitting corrosion [16].
1.1 Research Motivation. - The strength and hardness of Al 6082-T6 significantly deteriorate due to the high heat
input generated during the welding process. A comprehensive literature review reveals that this degradation primarily
results from substantial microstructural alterations induced by welding. Given the high thermal conductivity of
aluminium, heat is rapidly conducted, leading to an expanded HAZ and subsequent microstructural disruptions, which
frequently contribute to joint failure. Moreover, the ductility of welded joints is considerably reduced due to
microstructural distortion and reinforcement through the incorporation of additional filler metal. This study explores
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
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the potential enhancement of the mechanical properties of Al 6082-T6 weld joints through post-weld quenching using
various cooling media following TIG welding. The HAZ width in samples cooled under ambient air conditions is
relatively larger due to the slower heat dissipation, which negatively impacts tensile strength, impact resistance, and
hardness. Minimizing the HAZ width is crucial for improving the mechanical performance of welded joints. Therefore,
rapid dissipation of post-welding heat is essential to mitigate mechanical property degradation. This investigation
evaluates the effect of different cooling media on the mechanical behaviour of Al 6082-T6, recognizing that each
cooling medium exhibits distinct heat transfer characteristics, leading to variations in the resulting mechanical
properties of the weld joints.
2. Experimental Methodology. - TIG welding technique was utilized in this study for welding of Al 6082-T6 alloy
of 8mm thickness, different quenching media were used immediately after welding process to alter mechanical
properties and welding efficiency. Following parameters were studied:
a. Microstructural examination
b. Tensile testing
c. Hardness testing
d. Impact testing
To investigate variations in strength and ductility, the researchers conducted tensile testing. Tensile samples were
prepared according to the ASTM E8M-16a standard, and a H150KV tensile testing machine (UTM) was employed for
this research. The hardness of the samples was evaluated using an Ernst Vickers Hardness Tester. Four different
quenching media air, sand, water, and hydraulic oil (Shell Morlina S2 BL 10) were selected for the purpose of cooling.
To assess toughness after the cooling process of welded samples, Charpy V-notch impact testing was performed
following the ASTM E23-18 standard for sample preparation. Microstructural examination of properly prepared
metallurgical specimens/weldments was conducted using an Optical Metallurgical Microscope. The chemical
composition of the material was determined using an optical emission spectrometer, and the weight percentages of
constituent elements are presented in Table I. For comparison with the welded samples, the mechanical properties of
the base material were tabulated in Table II. Based on a comprehensive review of the literature, suitable welding
parameters were selected to achieve high-quality welded joints.
Element
Mg
Si
Mn
Cu
Cr
Zn
Ti
Fe
Al
Percentage
1
.7
.95
.13
.26
.21
.12
.48
Balance
Table I: Chemical composition of Al 6082-T6
Base material specimens were cut from 8 mm thick plate and tensile specimens were prepared as per ASTM E8M-16a
standard.
Base metal
Yield strength (YS)
Tensile strength (UTS)
% Elongation
Hardness Vicker (HV)
Al 6082-T6
250MPa
300MPa
10%
90
Table II: Base material mechanical properties
For TIG welding, the welding parameters chosen were an electrode traveling speed of 200 mm/min and a current of
180 A. The welding process utilized a Precision TIG AC type machine, and a 3.2mm diameter filler wire AA4043 was
selected. To prevent any interference with the mechanical properties, the dwell time after welding was kept to a
minimum.
3. Results and Discussion. -
3.1 Microstructure Study. - Microstructural study was performed to evaluate the impact of different cooling media
on HAZ of welding joints of Al 6082 T6. The microstructural examination presented in Figure I illustrates distinct
grain boundaries within the HAZ. Coarse grain boundaries were observed in both Figure I(a) and Figure I(b),
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contributing to improved elongation percentage and ductility but reduced strength. Conversely, Figure I(c) and Figure
I(d) depict fine grain boundaries resulting from the rapid cooling process involving water and oil. Notably, oil cooling
leads to the formation of elongated grains, as evident in Figure I(d). In comparison, joints cooled with air and sand
exhibit higher levels of porosity when compared to those cooled with water and oil. The presence of pores creates
points of stress concentration, ultimately causing a degradation in the mechanical strength of the joints. Microstructural
analysis of oil cooled joints reveals the presence of fine and equiaxed grains due to the moderate viscosity of the oil,
which facilitates quick and uniform heat dissipation without the formation of a vapor shield.
(a) Air cooled joints (b) Sand cooled joints
(c) Water cooled joints (d) Hydraulic-oil cooled joints
Figure I: Microstructure of HAZ of Air, Sand, Water & Hydraulic-oil cooled joints.
Water-cooled joints exhibit fine yet irregular grains due to their rapid but non-uniform cooling process. The black spots
observed in the HAZ of air-cooled and sand-cooled samples likely result from the formation of secondary phases, such
as Mg₂Si precipitates or other intermetallic compounds, during cooling. The slower cooling rates in air and sand
facilitated the diffusion of precipitates along coarse grain boundaries. These precipitates appear darker under optical
microscopy due to their distinct optical properties compared to the aluminium matrix. In contrast, rapid cooling in
water and oil quenching leaves less time for precipitate formation and growth. Instead, the rapid cooling rate traps
solute atoms within the aluminium matrix, inhibiting the development of distinct precipitates. Consequently, black
spots are smaller or less noticeable in these samples. Additionally, slower cooling rates may encourage the segregation
of elements like Mg or Si at grain boundaries. Rapid cooling, on the other hand, promotes fine grain boundaries,
enhancing mechanical strength while reducing the ductility of welded joints. The formation of precipitates restricts
dislocation motion under loading, leading to increased strength. Rapid cooling seizes these precipitates along fine grain
boundaries, potentially contributing to strength enhancement. This precipitation effect is counteracted by the presence
of pores and coarse grain boundaries, meaning slow cooling may not significantly improve strength and hardness.
3.2 Tensile Testing Results. - The strength (both tensile and yield) of welded joints decreased by approximately 50%
as a result of the weld heat input effects [5]. Figure II represents the outcomes of the comparison between the yield
strength (YS) of welded joints that were quenched or cooled using different cooling methods. For each cooling
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
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treatment, three samples were chosen, and the comparison was based on the average values. The water-quenched
welded samples exhibited a higher YS compared to the samples cooled in air, sand, and oil. This improvement in YS
was achieved because the rapid cooling in water led to the formation of fine grain boundaries.
Figure II: Quenching effect on yield strength.
The YS of the oil-quenched welded samples was similar to that of the water-quenched samples due to the higher
convectional coefficients facilitating temperature distribution. Additionally, low distortions were observed after oil
quenching. The YS of the air and sand-cooled samples were approximately equal since both cases involved slower
cooling. Several distortions were observed after water quenching due to its very rapid cooling process. The findings
presented in Figure IV illustrate a comparison of the ultimate tensile strength (UTS) among welded joints that were
cooled using different quenching media. It was observed that the oil-cooled welded joints displayed higher strength
compared to joints cooled in other media. The strength characteristics of the oil-cooled joints were particularly
distinctive, showing an improvement of 54MPa compared to the normally air-cooled welded joints. The tensile strength
of the oil-cooled joints also exhibited a notable difference of approximately 26MPa when compared to the water-cooled
joints. Additionally, Figure III presents the results indicating the ductile behavior of the welded joints cooled in various
media. Base metal ductility reduced from 10% elongation to 6% for normal air-cooled welded joints. Oil cooled
samples showed 7% elongation, highest amongst other media; thus, oil cooling imparted maximum ductility after
welding due to uniform diffusion of precipitates along grains and moderate cooling.
Figure III: Quenching effect on percent elongation.
Fine grain boundaries generally enhance the endurance limit, leading to improved fatigue strength. Rapid cooling
methods such as water and oil cooling can further increase fatigue resistance by maximizing dislocation hindrance. In
contrast, coarse grain boundaries formed through slower cooling methods like air and sand cooling may reduce fatigue
strength due to lower resistance to dislocation movement. Additionally, slow cooling can result in gas porosity, which
creates stress concentrations and further diminishes endurance properties.
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
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Figure IV: Quenching effect on ultimate tensile strength.
3.3 Welding Efficiency. - The results presented in Figure V demonstrate an enhancement in welding efficiency when
utilizing different quenching media for the welded joints compared to normal air-cooled joints. Among the quenching
methods, oil-quenched joints exhibited the highest weld efficiency of 72.5%.
Figure V: Welding Efficiency.
This improvement can be attributed to the development of fine grain boundaries, which occurred due to the higher
cooling rate provided by oil quenching compared to air and sand. Additionally, the width of the HAZ was reduced,
resulting in improved mechanical properties, as a narrower HAZ is associated with better performance. In both the
HAZ and WZ, the coarsening of precipitation size was not significant due to the rapid cooling process, leading to
smaller and finer precipitates. Consequently, the oil-quenched joints exhibited higher strength compared to the other
methods. On the other hand, water-quenched joints showed strength improvements of up to 64.6%. However, their
strength was lower than that of oil-cooled joints due to the extremely rapid cooling in water. Although the water-
quenched joints displayed lower tensile strength due to the generation of internal stresses, their yield strength was
higher than that of the oil-quenched joints. This can be attributed to the presence of fine grain boundaries and the
hindrance of dislocations caused by the rapid water cooling.
3.4 Hardness Testing. - The hardness testing results presented in Figure VI illustrate a comparison among the WZ of
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
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welded joints that were subjected to quenching in various media. Among the different quenching methods employed,
the welded joints quenched in water displayed the highest hardness in the WZ. This can be attributed to the segregation
of fine grain boundaries and the formation of narrow precipitates, which were more pronounced in comparison to the
other quenched joints. The utilization of oil cooling resulted in an enhancement of hardness, increasing it from 56HV
(for joints cooled in normal air) to 68HV.
Figure VI: Quenching effect on WZ hardness.
Notably, sand cooling did not yield any significant changes in the welded joints, as the results were similar to those of
the air-cooled joints. The input heat effected the width of both the WZ and the HAZ, leading to a decrease in hardness
for joints that were slowly cooled (via air and sand) from 90HV to approximately 55HV. The results presented in
Figure VII demonstrate a comparison of the hardness in the HAZ of different welding joints after quenching. The HAZ
hardness of joints quenched in water was found to be the highest among the various joints, primarily due to the rapid
cooling process. The oil-cooled joints exhibited a similar level of hardness in the HAZ, closely following the water-
cooled joints. The increased hardness observed in the water and oil-cooled joints can be attributed to the extremely
narrow width of the HAZ and the presence of fine precipitates. The rapid cooling employed in these methods restricts
the movement of dislocations, leading to the generation of stresses across the crystallographic planes. However, it
should be noted that the fast cooling of welded joints in water can result in brittleness, which further increases the
hardness and can have a detrimental effect on the tensile strength of the joints.
Figure VII: Quenching effect on HAZ Hardness.
3.5 Impact Testing. - The impact absorbed energy (measured in Joules) of the WZ in different media after quenching
0
10
20
30
40
50
60
70
80
Air Sand Water Oil
Hardness(HV)
Cooling Media
0
10
20
30
40
50
60
70
80
90
Air Sand Water Oil
Hardness(HV)
Cooling Media
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is presented in Figure VIII. The amount of impact energy absorbed during testing directly reflects the toughness of the
welded joints, as toughness is directly proportional to impact energy. It was observed that the water-cooled welded
joints exhibited brittleness. On the other hand, slow cooling in air and sand resulted in generally good toughness due
to their favorable ductile nature. The slow cooling process minimizes the generation of internal stresses. However, it
should be noted that the microstructure of the sand and air-cooled samples showed signs of porosity. In comparison,
the air and sand-cooled welded joints displayed higher impact energy in the WZ compared to the water-cooled joints.
In contrast, the WZ of oil-cooled joints exhibited enhanced toughness compared to the other joints. This improvement
can be attributed to the fact that the viscosity of the oil allowed for the uniform distribution of input heat throughout
the entire area around the WZ, effectively reducing porosity. The moderate cooling provided by the oil, which has
higher viscosity than other media, contributed to an overall improvement in impact resistance. Abrupt temperature
changes due to fast cooling in water resulted in severe internal stresses and restricted dislocation movement eventually
causing the welded joints to become brittle.
Figure VIII: Quenching effect on WZ Impact Energy
The impact energy of the HAZ in welded joints, quenched using different media, is depicted in Figure IX. Among the
various quenching methods, the oil-cooled joints displayed the highest impact energy, measuring 25.5 Joules. This
superior performance can be attributed to the uniform distribution of input heat achieved through the moderate viscosity
of the oil. Although oil cooling is a faster process compared to air and sand cooling, water cooling is even faster than
oil cooling. As a result, the water-cooled joints exhibited a lower impact energy due to the rapid cooling process, which
restricts dislocation motion owing to the extremely narrow HAZ. On the other hand, air and sand-cooled joints
experienced uneven heat distribution, which facilitated dislocation motion and led to a wider HAZ. Consequently,
these joints demonstrated lower impact energy. However, when the welded joints were oil-cooled, they exhibited mild
effects and demonstrated enhanced impact energy. This suggests that the oil cooling method had positive effects on
the joints. It is important to note that the quenching media used in the experiments were assumed to be at standard
temperature. All the experiments were conducted within a carefully controlled laboratory environment, without any
heating or cooling of the quenching media being performed.
Figure IX: Quenching effect on HAZ Impact Energy.
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Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 67
Table III presents the statistical analysis of the data, highlighting that the ultimate tensile strength exhibited the highest
standard deviation. This variability can be attributed to rapid cooling, as UTS increased significantly due to post-weld
quenching. Furthermore, the UTS data demonstrated the largest range of 48, reinforcing the correlation between
enhanced UTS and swift cooling in comparison to air and sand cooling methods. Similarly, the hardness of the HAZ
showed a notable improvement, likely due to refined grain boundaries and precipitate formation. A range of 20 was
observed in hardness values, indicating a substantial variation in response to different cooling conditions.
Mean
Median
Standard Deviation
Range
UTS
189.2
184.5
19.7
48
YS
126.75
126
10.52
25
% Elongation
6.13
6
0.61
1.7
Hardness
WZ
63.25
62
8.04
19
HAZ
73.5
71
9.13
20
Impact
Energy
WZ
4.9
5.1
1.4
3.5
HAZ
21.8
22.4
3.53
8.5
Table III: Statistical Analysis of data.
4. Conclusion. - The utilization of different media for quenching weld joints leads to improved mechanical properties
due to rapid heat dissipation from the joint area, key improvements are listed below:
The strength of welded joints is compromised by normal air cooling, resulting in a decrease of up to 50%.
Among the various quenching media, water-cooled joints exhibited the highest YS of 140 MPa.
Oil cooling enhanced the UTS of joints cooled in air from 170 MPa to 221 MPa. Likewise, oil-cooled joints
demonstrated the highest percentage of elongation, indicating superior ductility.
Oil quenching resulted in the maximum weld efficiency of 72.5%, surpassing the 55.7% efficiency of normally
air-cooled joints. The notable weld efficiency achieved in oil-cooled joints can be attributed to the moderate
viscosity of hydraulic oil.
The water-cooled joints exhibited higher hardness in the WZ and HAZ compared to other joints. The increased
hardness is attributed to residual internal stresses at crystallographic planes.
The impact energy of water-cooled welded joints decreased to 3 Joules in the WZ, while the impact energy of
oil-cooled joints surpassed other joints. In the HAZ, the impact energy of oil-cooled joints was distinct and
the highest among all joints due to the narrow width of the HAZ, fine grain boundaries, and fine precipitates.
Overall, oil-quenched welded joints demonstrated superior performance compared to other welded joints.
5. Future Recommendation. - This study conducted microstructural analysis and mechanical characterization,
including tensile, hardness, and impact testing, on quenched welded joints. The scope of mechanical evaluation can be
further expanded by incorporating fatigue and creep analysis. Additionally, post-weld heat treatment can be employed
to assess the performance of the welded joints. Processes such as solution heat treatment and artificial aging have the
potential to induce significant microstructural modifications and alter the mechanical properties of the material.
A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 68
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A. Shazad, M. Uzair, J. Jadoon, S. Khan Marwat
Memoria Investigaciones en Ingeniería, núm. 28 (2025). pp. 58-70
https://doi.org/10.36561/ING.28.6
ISSN 2301-1092 • ISSN (en línea) 2301-1106 – Universidad de Montevideo, Uruguay 70
Author contribution:
1. Conception and design of the study
2. Data acquisition
3. Data analysis
4. Discussion of the results
5. Writing of the manuscript
6. Approval of the last version of the manuscript
AS has contributed to: 1, 2, 3, 4, 5 and 6.
MU has contributed to: 1, 2, 3, 4, 5 and 6.
JJ has contributed to: 1, 2, 3, 4, 5 and 6.
SKM has contributed to: 1, 2, 3, 4, 5 and 6.
Acceptance Note: This article was approved by the journal editors Dr. Rafael Sotelo and Mag. Ing. Fernando A.
Hernández Gobertti.
