Numerical and experimental analysis of welding residual stress distribution and its effects on the mechanical properties and microstructure of dissimilar authenti stainless steel and structural steel SMAW joints.
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Date
2026
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Busitema University
Abstract
Dissimilar-metal welding is increasingly used where combinations of corrosion resistance, mechanical strength and economic material utilization are required. However, joining austenitic stainless steel to structural steel produces complex thermal and mechanical interactions that can generate no uniform welding residual stresses and associated variations in mechanical performance and microstructure. This study investigated residual-stress distribution in shielded metal arc welded (SMAW) butt joints between Grade 304 austenitic stainless steel and ASTM A36 structural steel plates of 6, 8, 10 and 12 mm thickness. E7018 low-hydrogen electrodes were used, with the number of weld passes increasing with plate thickness. A combined numerical and experimental approach was adopted. Finite element analysis in ANSYS was used to estimate the magnitude and spatial distribution of welding induced principal stresses, while transverse tensile testing, Rockwell hardness measurements and optical metallography were used to characterize mechanical and microstructural responses. The numerical results indicated that residual stresses were non-uniformly distributed, with the highest stress concentrations occurring around the fusion boundary and at weld start and termination regions. Plate thickness, material property mismatch, local thermal gradients and repeated thermal cycles from multi-pass welding influenced the predicted stress fields. For the 12 mm joint, the model produced a minimum principal stress of -940.90 MPa, a maximum local principal stress of 5,846.10 MPa and an average principal stress of 249.63 MPa at 180 s. Because the isolated maximum greatly exceeded the expected yield strengths of the constituent materials, it was interpreted cautiously as a likely numerical stress concentration requiring mesh-convergence and experimental validation. The ultimate tensile strengths for 6, 8, 10 and 12 mm joints were 503, 517, 579 and 523 MPa, respectively, while the corresponding yield strengths were 482, 389, 428 and 473 MPa. The 8 mm joint showed the lowest elongation (73.5%), whereas the 10 and 12 mm joints reached 90.5%. Hardness and metallographic observations confirmed that welding produced location- and thickness-dependent changes across the fusion and heat-affected zones. Overall, the results demonstrate that plate thickness and welding thermal history influence the residual-stress field and the associated mechanical and microstructural condition of dissimilar SMAW joints. The study recommends optimisation of welding parameters and post-weld treatment, together with experimental residual-stress measurement to validate and refine the numerical model.
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Undergraduate research report
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Ssebukulu, G. (2026). Numerical and experimental analysis of welding residual stress distribution and its effects on the mechanical properties and microstructure of dissimilar authenti stainless steel and structural steel SMAW joints. [Unpublished undergraduate research report]. Busitema University.