Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding

Delelegn Gizaw Toga; Seyidu Wohabrebi; Misganu Kabeta; Samuel Alemu

doi:doi:10.11648/j.ijmea.20261405.16

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| Peer-Reviewed

Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding

Delelegn Gizaw Toga^*

, Seyidu Wohabrebi

, Misganu Kabeta

, Samuel Alemu

Published in International Journal of Mechanical Engineering and Applications (Volume 14, Issue 5)

Received: 27 August 2026 Accepted: 28 September 2026 Published: 26 October 2026

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Abstract

Welding defects pose significant challenges to product quality and productivity in manufacturing industries. Shielded metal arc welding (SMAW) is the most widely used welding method in developing countries such as Ethiopia. This thesis identifies and addresses the root causes of welding defects in SMAW of medium carbon steel (AISI 4145) at Akaki Basic Metal Industry (ABMI), and optimizes welding parameters to enhance weld quality and reduce defect rates. Pareto analysis identified porosity and undercut as the most critical defects, together accounting for a 6% rejection rate in production over two years. Ishikawa (cause-and-effect) diagrams were used to analyze the root causes of these defects in detail, including incorrect welding parameters, inadequate preheat/post-heat treatment, improper technique, and inconsistent quality checks. A Taguchi L9 orthogonal array was then applied to optimize welding current, voltage, and speed. Welding current had the greatest effect on tensile strength (72.18% contribution), followed by voltage (19.73%) and speed (3.88%). Applying the optimized parameters (140 A, 40 V, 80 mm/s) reduced the defect rate from 6% to 2.7%. The study concludes that systematic optimization of welding parameters can effectively mitigate defects, improve weld quality, and enhance productivity in SMAW processes.

Published in	International Journal of Mechanical Engineering and Applications (Volume 14, Issue 5)
DOI	10.11648/j.ijmea.20261405.16
Page(s)	141-157
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Shielded Metal Arc Welding, AISI 4145, Welding Defects, Pareto Analysis, Ishikawa Diagram, Taguchi Experimental Design

References

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APA Style

Toga, D. G., Wohabrebi, S., Kabeta, M., Alemu, S. (2026). Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. International Journal of Mechanical Engineering and Applications, 14(5), 141-157. https://doi.org/10.11648/j.ijmea.20261405.16

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ACS Style

Toga, D. G.; Wohabrebi, S.; Kabeta, M.; Alemu, S. Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. Int. J. Mech. Eng. Appl. 2026, 14(5), 141-157. doi: 10.11648/j.ijmea.20261405.16

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AMA Style

Toga DG, Wohabrebi S, Kabeta M, Alemu S. Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. Int J Mech Eng Appl. 2026;14(5):141-157. doi: 10.11648/j.ijmea.20261405.16

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@article{10.11648/j.ijmea.20261405.16,
  author = {Delelegn Gizaw Toga and Seyidu Wohabrebi and Misganu Kabeta and Samuel Alemu},
  title = {Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding},
  journal = {International Journal of Mechanical Engineering and Applications},
  volume = {14},
  number = {5},
  pages = {141-157},
  doi = {10.11648/j.ijmea.20261405.16},
  url = {https://doi.org/10.11648/j.ijmea.20261405.16},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijmea.20261405.16},
  abstract = {Welding defects pose significant challenges to product quality and productivity in manufacturing industries. Shielded metal arc welding (SMAW) is the most widely used welding method in developing countries such as Ethiopia. This thesis identifies and addresses the root causes of welding defects in SMAW of medium carbon steel (AISI 4145) at Akaki Basic Metal Industry (ABMI), and optimizes welding parameters to enhance weld quality and reduce defect rates. Pareto analysis identified porosity and undercut as the most critical defects, together accounting for a 6% rejection rate in production over two years. Ishikawa (cause-and-effect) diagrams were used to analyze the root causes of these defects in detail, including incorrect welding parameters, inadequate preheat/post-heat treatment, improper technique, and inconsistent quality checks. A Taguchi L9 orthogonal array was then applied to optimize welding current, voltage, and speed. Welding current had the greatest effect on tensile strength (72.18% contribution), followed by voltage (19.73%) and speed (3.88%). Applying the optimized parameters (140 A, 40 V, 80 mm/s) reduced the defect rate from 6% to 2.7%. The study concludes that systematic optimization of welding parameters can effectively mitigate defects, improve weld quality, and enhance productivity in SMAW processes.},
 year = {2026}
}

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TY  - JOUR
T1  - Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding
AU  - Delelegn Gizaw Toga
AU  - Seyidu Wohabrebi
AU  - Misganu Kabeta
AU  - Samuel Alemu
Y1  - 2026/10/26
PY  - 2026
N1  - https://doi.org/10.11648/j.ijmea.20261405.16
DO  - 10.11648/j.ijmea.20261405.16
T2  - International Journal of Mechanical Engineering and Applications
JF  - International Journal of Mechanical Engineering and Applications
JO  - International Journal of Mechanical Engineering and Applications
SP  - 141
EP  - 157
PB  - Science Publishing Group
SN  - 2330-0248
UR  - https://doi.org/10.11648/j.ijmea.20261405.16
AB  - Welding defects pose significant challenges to product quality and productivity in manufacturing industries. Shielded metal arc welding (SMAW) is the most widely used welding method in developing countries such as Ethiopia. This thesis identifies and addresses the root causes of welding defects in SMAW of medium carbon steel (AISI 4145) at Akaki Basic Metal Industry (ABMI), and optimizes welding parameters to enhance weld quality and reduce defect rates. Pareto analysis identified porosity and undercut as the most critical defects, together accounting for a 6% rejection rate in production over two years. Ishikawa (cause-and-effect) diagrams were used to analyze the root causes of these defects in detail, including incorrect welding parameters, inadequate preheat/post-heat treatment, improper technique, and inconsistent quality checks. A Taguchi L9 orthogonal array was then applied to optimize welding current, voltage, and speed. Welding current had the greatest effect on tensile strength (72.18% contribution), followed by voltage (19.73%) and speed (3.88%). Applying the optimized parameters (140 A, 40 V, 80 mm/s) reduced the defect rate from 6% to 2.7%. The study concludes that systematic optimization of welding parameters can effectively mitigate defects, improve weld quality, and enhance productivity in SMAW processes.
VL  - 14
IS  - 5
ER  -

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Author Information

Delelegn Gizaw Toga

Mineral Industry Development Institute, Ministry of Mines, Addis Ababa, Ethiopia

Contact Email

http://orcid.org/0009-0003-1633-6369
Seyidu Wohabrebi

Mineral Industry Development Institute, Ministry of Mines, Addis Ababa, Ethiopia

Contact Email

http://orcid.org/0009-0005-4452-6447
Misganu Kabeta

Mineral Industry Development Institute, Ministry of Mines, Addis Ababa, Ethiopia

Contact Email

http://orcid.org/0009-0004-6364-6105
Samuel Alemu

Mineral Industry Development Institute, Ministry of Mines, Addis Ababa, Ethiopia

Contact Email

http://orcid.org/0009-0006-8922-4079

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APA Style

Toga, D. G., Wohabrebi, S., Kabeta, M., Alemu, S. (2026). Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. International Journal of Mechanical Engineering and Applications, 14(5), 141-157. https://doi.org/10.11648/j.ijmea.20261405.16

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ACS Style

Toga, D. G.; Wohabrebi, S.; Kabeta, M.; Alemu, S. Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. Int. J. Mech. Eng. Appl. 2026, 14(5), 141-157. doi: 10.11648/j.ijmea.20261405.16

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AMA Style

Toga DG, Wohabrebi S, Kabeta M, Alemu S. Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding. Int J Mech Eng Appl. 2026;14(5):141-157. doi: 10.11648/j.ijmea.20261405.16

Copy | Download

@article{10.11648/j.ijmea.20261405.16,
  author = {Delelegn Gizaw Toga and Seyidu Wohabrebi and Misganu Kabeta and Samuel Alemu},
  title = {Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding},
  journal = {International Journal of Mechanical Engineering and Applications},
  volume = {14},
  number = {5},
  pages = {141-157},
  doi = {10.11648/j.ijmea.20261405.16},
  url = {https://doi.org/10.11648/j.ijmea.20261405.16},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijmea.20261405.16},
  abstract = {Welding defects pose significant challenges to product quality and productivity in manufacturing industries. Shielded metal arc welding (SMAW) is the most widely used welding method in developing countries such as Ethiopia. This thesis identifies and addresses the root causes of welding defects in SMAW of medium carbon steel (AISI 4145) at Akaki Basic Metal Industry (ABMI), and optimizes welding parameters to enhance weld quality and reduce defect rates. Pareto analysis identified porosity and undercut as the most critical defects, together accounting for a 6% rejection rate in production over two years. Ishikawa (cause-and-effect) diagrams were used to analyze the root causes of these defects in detail, including incorrect welding parameters, inadequate preheat/post-heat treatment, improper technique, and inconsistent quality checks. A Taguchi L9 orthogonal array was then applied to optimize welding current, voltage, and speed. Welding current had the greatest effect on tensile strength (72.18% contribution), followed by voltage (19.73%) and speed (3.88%). Applying the optimized parameters (140 A, 40 V, 80 mm/s) reduced the defect rate from 6% to 2.7%. The study concludes that systematic optimization of welding parameters can effectively mitigate defects, improve weld quality, and enhance productivity in SMAW processes.},
 year = {2026}
}

Copy | Download

TY  - JOUR
T1  - Mitigating Weld Defects in AISI 4145 Medium-Carbon Steel During Shielded Metal Arc Welding
AU  - Delelegn Gizaw Toga
AU  - Seyidu Wohabrebi
AU  - Misganu Kabeta
AU  - Samuel Alemu
Y1  - 2026/10/26
PY  - 2026
N1  - https://doi.org/10.11648/j.ijmea.20261405.16
DO  - 10.11648/j.ijmea.20261405.16
T2  - International Journal of Mechanical Engineering and Applications
JF  - International Journal of Mechanical Engineering and Applications
JO  - International Journal of Mechanical Engineering and Applications
SP  - 141
EP  - 157
PB  - Science Publishing Group
SN  - 2330-0248
UR  - https://doi.org/10.11648/j.ijmea.20261405.16
AB  - Welding defects pose significant challenges to product quality and productivity in manufacturing industries. Shielded metal arc welding (SMAW) is the most widely used welding method in developing countries such as Ethiopia. This thesis identifies and addresses the root causes of welding defects in SMAW of medium carbon steel (AISI 4145) at Akaki Basic Metal Industry (ABMI), and optimizes welding parameters to enhance weld quality and reduce defect rates. Pareto analysis identified porosity and undercut as the most critical defects, together accounting for a 6% rejection rate in production over two years. Ishikawa (cause-and-effect) diagrams were used to analyze the root causes of these defects in detail, including incorrect welding parameters, inadequate preheat/post-heat treatment, improper technique, and inconsistent quality checks. A Taguchi L9 orthogonal array was then applied to optimize welding current, voltage, and speed. Welding current had the greatest effect on tensile strength (72.18% contribution), followed by voltage (19.73%) and speed (3.88%). Applying the optimized parameters (140 A, 40 V, 80 mm/s) reduced the defect rate from 6% to 2.7%. The study concludes that systematic optimization of welding parameters can effectively mitigate defects, improve weld quality, and enhance productivity in SMAW processes.
VL  - 14
IS  - 5
ER  -

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