Memoria Investigaciones en IngenierÃa, núm. 28 (2025). pp. 45-57
https://doi.org/10.36561/ING.28.5
ISSN 2301-1092 • ISSN (en lÃnea) 2301-1106 – Universidad de Montevideo, Uruguay
Este es un artÃculo 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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Memoria Investigaciones en IngenierÃa, núm. 28 (2025). pp. 45-57
https://doi.org/10.36561/ING.28.5
ISSN 2301-1092 • ISSN (en lÃnea) 2301-1106 – Universidad de Montevideo, Uruguay
Este es un artÃculo de acceso abierto distribuido bajo los términos de una licencia de uso y distribución CC BY-NC 4.0. Para ver
una copia de esta licencia visite http://creativecommons.org/licenses/by-nc/4.0/
Post Weld Quenching Impact on Microstructure and Mechanical Properties
(Tensile, Impact, Hardness) of High Strength Low Alloy Steel
Impacto del temple posterior a la soldadura en la microestructura y las
propiedades mecánicas del acero de baja aleación y alta resistencia
Impacto da têmpera pós-soldagem na microestrutura e nas propriedades mecânicas
de aços de alta resistência e baixa liga
Atif Shazad
1
(*), Muhammad Uzair
2
Recibido: 27/09/2024 Aceptado: 26/01/2025
Summary. - Shielded Metal Arc Welding (SMAW) is the most widely used welding technique in engineering
industries. Compared to other arc welding techniques like TIG, SMAW is less heat-concentrating. However, welding
thick jobs using SMAW can result in serious issues such as structural distortion due to non-uniform input heat
distribution. High thermal stresses and distortions can degrade mechanical properties, similar to high input heat. Fast
heat removal may prevent such defects, and different quenching media like sand, water, and oil were used to investigate
variations in mechanical properties. High-strength low-alloy steel was selected due to its good weldability and easy
availability, which makes it suitable for many industrial applications, such as in the space and defense industries. The
tensile testing results showed that oil quenching was superior to other quenching techniques because oil-cooled joints
had the highest tensile strength and ductility. However, water-cooled joints showed the highest yield strength, but oil-
quenched joints had the highest welding efficiency. The hardness of water-cooled joints in the heat-affected zone and
weld zone was greater due to rapid cooling in water. The impact energy of oil-cooled joints in the heat-affected zone
was superior to that of other joints. Overall, the mechanical properties of oil-cooled joints were superior and showed
better geometric configuration, such as minimal distortions.
Keywords: Tensile strength; hardness; Impact strength; SMAW; High strength low alloy steel; quenching media.
1
Research Scholar, NEDUET (Pakistan), atifshahzad2717@gmail.com, ORCID iD: https://orcid.org/0000-0002-3277-7901
2
Associate Professor, NEDUET (Pakistan), uzair@neduet.edu.pk, ORCID iD: https://orcid.org/0000-0002-2033-6244
A. Shazad, M. Uzair
Memoria Investigaciones en IngenierÃa, núm. 28 (2025). pp. 45-57
https://doi.org/10.36561/ING.28.5
ISSN 2301-1092 • ISSN (en lÃnea) 2301-1106 – Universidad de Montevideo, Uruguay 46
Resumen. - La soldadura por arco metálico protegido (SMAW) es la técnica de soldadura más utilizada en las
industrias de ingenierÃa. En comparación con otras técnicas de soldadura por arco como TIG, SMAW concentra menos
calor. Sin embargo, soldar trabajos gruesos utilizando SMAW puede provocar problemas graves, como distorsión
estructural debido a una distribución no uniforme del calor de entrada. Las altas tensiones y distorsiones térmicas
pueden degradar las propiedades mecánicas, de forma similar al calor de entrada elevado. La eliminación rápida del
calor puede prevenir tales defectos, y se utilizaron diferentes medios de enfriamiento como arena, agua y aceite para
investigar las variaciones en las propiedades mecánicas. Se seleccionó acero de alta resistencia y baja aleación debido
a su buena soldabilidad y fácil disponibilidad, lo que lo hace adecuado para muchas aplicaciones industriales, como
en las industrias espacial y de defensa. Los resultados de las pruebas de tracción mostraron que el enfriamiento con
aceite fue superior a otras técnicas de enfriamiento porque las juntas enfriadas por aceite tenÃan la mayor resistencia
a la tracción y ductilidad. Sin embargo, las uniones enfriadas por agua mostraron el lÃmite elástico más alto, pero las
uniones enfriadas con aceite tuvieron la mayor eficiencia de soldadura. La dureza de las uniones enfriadas por agua
en la zona afectada por el calor y en la zona de soldadura fue mayor debido al rápido enfriamiento en agua. La energÃa
de impacto de las juntas enfriadas por aceite en la zona afectada por el calor fue superior a la de otras juntas. En
general, las propiedades mecánicas de las juntas enfriadas por aceite fueron superiores y mostraron una mejor
configuración geométrica, como distorsiones mÃnimas.
Palabras clave: Resistencia a la tracción; dureza; Fuerza de impacto; SMAW; Acero de baja aleación de alta
resistencia; medios de enfriamiento.
Resumo. - A soldagem por arco metálico blindado (SMAW) é a técnica de soldagem mais amplamente utilizada nas
indústrias de engenharia. Em comparação com outras técnicas de soldagem a arco, como TIG, o SMAW concentra
menos calor. No entanto, a soldagem de trabalhos espessos usando SMAW pode resultar em problemas sérios, como
distorção estrutural devido à distribuição não uniforme do calor de entrada. Altas tensões e distorções térmicas podem
degradar as propriedades mecânicas, semelhante à alta entrada de calor. A rápida remoção de calor pode prevenir
tais defeitos, e diferentes meios de têmpera como areia, água e óleo foram usados para investigar variações nas
propriedades mecânicas. O aço de alta resistência e baixa liga foi selecionado devido à sua boa soldabilidade e fácil
disponibilidade, o que o torna adequado para muitas aplicações industriais, como nas indústrias espacial e de defesa.
Os resultados dos testes de tração mostraram que a têmpera em óleo foi superior a outras técnicas de têmpera porque
as juntas resfriadas a óleo apresentaram maior resistência à tração e ductilidade. No entanto, as juntas resfriadas a
água apresentaram o maior limite de escoamento, mas as juntas temperadas a óleo tiveram a maior eficiência de
soldagem. A dureza das juntas resfriadas a água na zona afetada pelo calor e na zona de solda foi maior devido ao
rápido resfriamento em água. A energia de impacto das juntas resfriadas a óleo na zona afetada pelo calor foi superior
à das outras juntas. No geral, as propriedades mecânicas das juntas resfriadas a óleo foram superiores e apresentaram
melhor configuração geométrica, como distorções mÃnimas.
Palavras-chave: Resistência à tracção; dureza; Resistência ao impacto; SMAW; Aço de baixa liga de alta resistência;
meios de extinção.
A. Shazad, M. Uzair
Memoria Investigaciones en IngenierÃa, núm. 28 (2025). pp. 45-57
https://doi.org/10.36561/ING.28.5
ISSN 2301-1092 • ISSN (en lÃnea) 2301-1106 – Universidad de Montevideo, Uruguay 47
1. Introduction. - Shielded Metal Arc Welding (SMAW) is widely used in various industries due to its affordability
and availability. It has a higher power density than gas fusion welding, but lower than Tungsten Inert Gas (TIG)
welding. However, extensive distortions can occur during SMAW due to the low concentration of flame. Skilled
welders can be easily sourced locally. High Strength Low Alloy Steel, known for its durability and strength, is utilized
in upper atmosphere research, power production, and defense industries [1,2]. High Strength Low Alloy Steel is widely
used in various industries due to its exceptional strength to weight ratio, enhanced toughness, ductility, and weldability.
However, welding joints of low alloy high strength steel can experience a degradation of strength in the joined material.
Welded joints exhibit reduced hardness and impact strength, and their ductility is also mitigated. These changes in
mechanical properties are caused by the high heat input during welding, which results in alterations to both the
microstructure and macrostructure of the welded samples [3,4].
Srinivasan et al. conducted a research study and revealed that the impact of heat on the mechanical properties of TIG
welded joints made from High Strength Low Alloy (HSLA) steel. The study found that the strength of the welded
joints decreased to 55% of the strength of the base material due to the welding process [5,6]. To address this issue, the
samples were subjected to heat treatment, which resulted in an increase in strength. However, while other mechanical
properties such as hardness were improved, the ductility of the welded samples was found to be lower than that of the
base metal [7,8]. Sapthagiri et al. conducted a study on the impact of filler wire variation on the mechanical properties
of welded joints made from low alloy high strength steel. The study found that using copper-coated filler wire resulted
in an improvement in both yield strength and percent elongation [9].
Arc welding is more likely to produce defects such as angular and linear distortions compared to advanced techniques
like laser and electron beam welding. Rami et al. investigated the impact of different welding clamps used in gas metal
arc welding on the mechanical properties of the welded joints. The study found that using a heat treatment clamping
technique resulted in achieving welding efficiency of over 80% [10]. Srivastava et al. conducted a study on the
penetration depth of filler material in welding. The findings showed that changes in input heat and welding speed had
a negative impact on the penetration depth, which, in turn, affected the joint efficiency [11].
Li et al. studied the effect of changes in welding input heat on the mechanical properties of low carbon steel and found
that different microstructural phases were generated due to aberrations in cooling rate [12]. Eroglu et al. investigated
the microstructural variations in High Strength Low Alloy Steel caused by changes in input heat energy. They observed
that the hardness property in the weld region and heat-affected zone was reduced due to increased input heat. While
martensite was produced as a result of lower heat input, hardness property decreased beyond a certain point with further
increase in heat input [13]. Bijaya et al. conducted a study comparing the mechanical properties of mild steel joints
that were welded using GMAW and SMAW methods. The rapid cooling rate after welding resulted in the development
of bainite and martensite structures, which led to an increase in the hardness and tensile strength of the joints. However,
the impact strength was found to have been reduced [14]. Ruming et al. investigated the enhancement of mechanical
properties of welding joints through the addition of Cerium. The results revealed an improvement in toughness
attributed to the surplus of crack-free energy. Additionally, the tensile strength of low alloy steel was enhanced due to
the refined grain structure, resulting in a noticeable increase in welding efficiency upon the addition of Ce [15].
Narwadkar et al. conducted a study on the production of angular distortions in different types of welded joints. The
results indicated that the bevel groove joint was more susceptible to angular distortions than single and double V
groove joints, which were found to have lower angular distortions [16]. In another study, Adamczuk et al. investigated
the correlation between the number of welds passes and angular distortion. It was found that there was a direct
relationship between the number of passes and the angular distortions, with a greater shrinkage power resulting from
the welding of thicker plates due to the direct effect of increasing the amount of weld metal on angular distortions [17].
Wei et al. studied the impact of distortions on the performance of welding joints and revealed that distortions have a
direct effect on joint strength and dimensional accuracy [18]. Despite significant advancements in arc welding
technology, distortion induced by welding remains one of the most noticeable challenges in the production industry
for ensuring higher weld efficiency. Anis et al. investigated the impact of weld thickness and position on the residual
stress generated during welding due to the contraction and expansion of the welding joint [19,20]. Residual stresses
generated during welding hindered the joint efficiency increment, hence M Islam et al. performed a research work to
evaluate joint mechanical properties after different post welding treatments. Pre-bending and pre-heating are some
techniques utilized to control distortions [21,22].
2. Research Objective and Novelty. - The degradation of strength caused by high heat input during welding is a
primary factor contributing to joint failure under load. Uneven thermal distribution across the joint amplifies the effects
of residual stresses and increases the size of the Heat Affected Zone (HAZ). This study aims to improve the mechanical
A. Shazad, M. Uzair
Memoria Investigaciones en IngenierÃa, núm. 28 (2025). pp. 45-57
https://doi.org/10.36561/ING.28.5
ISSN 2301-1092 • ISSN (en lÃnea) 2301-1106 – Universidad de Montevideo, Uruguay 48
properties of welded joints. Achieving this goal is challenging due to the fact that high input heat during welding can
reduce the strength, ductility, hardness, and toughness of the welded structure by as much as 50% compared to the
base metal. The density of input energy, or the concentration of heat, is a critical factor influencing the performance
of welded joints. TIG welding is known for its high concentration of heat, whereas SMAW distributes the heat over a
wider area, ultimately diminishing the mechanical and microstructural properties. Therefore, this study focuses on
quenching the welded joints immediately after welding in various media to explore the impact on mechanical
properties. Distortions that arise in welded structures are a major cause of strength degradation. Uneven temperature
distribution across the welded joint causes distortions, ultimately weakening the structure. Consequently, enhancing
the mechanical properties is vital to ensuring the reliability of welded joints. Ductility is especially important in large
structures like pressure vessels. In this study, the quenching and cooling of welded joints immediately after welding
are investigated to assess their impact on the mechanical properties of welded structures.
3. Experimental Methodology. - Quenching media were selected from local market due to easy availability. Normally
welded joints are cooled in Air. Hence, to make direct comparative study welded joints after welding were cooled in
Air, Water, Sand and old hydraulic oil (used) etc. Following experiments were performed after cooling in different
media,
a. Tensile Testing
b. Impact testing
c. Hardness Testing
d. Microstructural characterization
High Strength Low Alloy Steel plate of 8mm thick was selected as base material and its chemical composition
performed by spectroscopy and mechanical properties of base material was evaluated by using Universal Testing
Machine (UTM) Tinius Olsen H150KV in material and metallurgy lab. Chemical composition of HSLA plate is
represented in Table I and mechanical properties are represented in Table II.
Element
C
Si
Mn
Mo
V
Cr
S
P
Fe
Maximum
0.18
0.22
0.98
1.12
0.27
1.25
0.018
0.017
Remaining
Table I: Spectroscopy results of High Strength Low Alloy Steel
Material
Yield stress (MPa)
Ultimate strength (MPa)
Elongation %
Hardness (HV)
High Strength Low
Alloy Steel
545
705
13
200
Table II: Tensile Strength and Hardness of Base metal (annealed state)
3x welded joints were tested in each testing category. Hardness testing and impact testing were performed to investigate
effects of variations in cooling media. Hardness of base metal was checked by using Ernst hardness tester. Charpy
Impact test was performed on machine of 300J capacity. Welding rod E-7018 was used for welding purpose, welding
current of around 150Amp and welding speed of 200mm/min were used as welding parameters. Impact testing samples
were prepared as per ASTM E23-18 standard. Charpy impact testing setup was utilized to evaluate toughness of welded
joints. All quenching media were at standard atmospheric values of temperature and pressure before quenching.
4. Results and Discussions. -
4.1 Microstructural characterization. - The microstructural study was conducted to assess the impact of different
quenching media on grain boundaries and grain sizes, which ultimately affect the mechanical properties. As shown in
Figures Ia and Ib, the air-cooled samples primarily consisted of a ferrite phase. The slow cooling rate due to natural
convection in air resulted in coarse ferrite grain boundaries and a minimal presence of pearlite, which was enveloped