Innovative Thermo-Kinetic Approaches in Welding: The Impact on Microstructural Integrity of AISI 304L and AISI 316L Stainless Steels

Authors

  • Ochuko Goodluck Utu Department of Mechanical Engineering, Chukwuemeka Ojukwu Odumegwu University – Nigeria; Department of Welding and Fabrication Engineering Technology, Delta State Polytechnic Ogwashi Uku
  • Ifeanyichukwu Ugochukwu Onyenanu Chukwuemeka Odumegwu Ojukwu University, Nigeria
  • Ifunanya Mariagoretti Onyenanu Caritas University, Enugu State - Nigeria

DOI:

https://doi.org/10.61424/rjcime.v1i1.162

Keywords:

Thermo-Kinetic Approaches, Microstructural Integrity, AISI 304L Stainless Steel, AISI 316L Stainless Steel, Heat Treatment

Abstract

AISI 304L and AISI 316L stainless steels, notable for their impressive corrosion resistance and mechanical attributes, find widespread application in the storage and transport of liquefied natural gas (LNG). Even so, these alloy types are susceptible to welding failure, a condition that involves the erosion of chromium at grain interfaces, which can weaken their overall structural soundness. This investigation explores novel thermo-kinetic methodologies aimed at mitigating weld decay in AISI 304L and AISI 316L weldments to prolong their operational lifespan in cryogenic settings. This investigation involved the development of 22 weldment test pieces employing tungsten inert gas (TIG) welding, succeeded by thermokinetic treatments at multiple temperatures (1050°C and 1150°C) for two-hour spans, and concluding with quenching in various substances: water, salt solution, and surrounding atmosphere. To evaluate alterations in microstructure and elemental content, the specimens underwent analysis via optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Optical microscopy indicated that the control specimen exhibited a more irregular microstructure in contrast to those subjected to thermokinetic treatments, with the optimal temperature of 1112.68°C resulting in a smoother, more densely packed microstructure in samples cooled at room temperature. In contrast, samples that underwent water quenching followed by annealing exhibited coarse surface characteristics. EDX findings validated the existence of iron (Fe), chromium (Cr), and nickel (Ni) while also highlighting notable variations in corrosion potential seen across the samples, which spanned from -0.5 to 0.15 V about the Ag/AgCl electrode. Furthermore, wear analysis revealed a marginal increase in the coefficient of friction (CoF), stabilizing at 0.6 after 200 seconds, suggesting an enhancement in wear resistance at lower CoF values. This study underscores the benefits of TIG welding over shielded metal arc welding (SMAW) in mitigating weld decay, attributable to superior heat control and diminished hazardous emissions. The findings provide critical insights into the thermokinetic processing of AISI 304L and AISI 316L stainless steels, establishing fundamental parameters for augmenting their performance in rigorous applications.

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Published

2024-12-11

How to Cite

Utu, O. G., Onyenanu, I. U., & Onyenanu, I. M. (2024). Innovative Thermo-Kinetic Approaches in Welding: The Impact on Microstructural Integrity of AISI 304L and AISI 316L Stainless Steels. Research Journal in Civil, Industrial and Mechanical Engineering, 1(1), 73–94. https://doi.org/10.61424/rjcime.v1i1.162