Phase transformation effect on residual stress development in fusion welding of dissimilar stainless steels with different thickness

• Published in: Archives of Civil and Mechanical Engineering Vol. 24; no. 3; p. 148
• Main Authors: Dwibedi, Swagat, Kumar, Bikash, Bag, Swarup
• Format: Journal Article
• Language: English
• Published: London Springer London 14.05.2024; Springer Nature B.V
• Subjects: Carbon steel; Civil Engineering; Compressive properties; Computation; Cooling; Electron backscatter diffraction; Engineering; Error analysis; Fusion welding; Grain boundaries; Heat conductivity; Mathematical models; Mechanical Engineering; Metal fatigue; Original Article; Phase transitions; Plasma arc welding; Plasma jets; Residual stress; Solidification; Stainless steel; Stainless steels; Steel alloys; Structural Materials; Thermal analysis; Thermal expansion; Thermophysical properties; Thickness; Distortion; Finite element modelling; Grain misorientation; Solidification mode; Phase fraction; Residual stress
• ISSN: 2083-3318; 1644-9665; 2083-3318
• DOI: 10.1007/s43452-024-00958-x

The residual stress creates deleterious effects on joint properties of dissimilar welding due to differential thermophysical properties and mechanical constraints of dissimilar thickness. Accounting of solid-state phase transformation (SSPT) through the understanding of solidification behavior enhances the prediction accuracy of residual stress. The characterization of microstructural features improves the fundamental understanding of the residual stress evaluation. An attempt is made to comprehend the dependence of heat input on phase transformation and its effect on the generation of compressive residual stress in dissimilar welding. Three distinct heat inputs of 52, 63, and 77 J/mm are considered in micro-plasma arc welding (µ-PAW) of SS316L and SS310 with thicknesses of 800 µm and 600 µm, respectively. The measurement of residual stress is performed using the X-ray diffraction (XRD) method. The variation of δ ferrite from 11.2 to 7.9% is analogous to the variation of average δ ferrite lath size from 412 to 1040 nm, where inter-dendritic spacing varies from ~ 10 µm to ~ 20 µm. The solidification mode is identified as ferritic-austenitic (FA), which results in the formation of skeletal and lathy δ ferrite structures. Electron Backscatter Diffraction (EBSD) results show an increase in heat input leads to an increase in low-angle grain boundaries that results in a rise in the residual stress value. The phase fraction and residual stresses are computed employing a finite element (FE) based thermal-metallurgical-mechanical (TMM) model including the effect of SSPT. The reasonable agreement between the computed and experimental measurements with a maximum error of ~ 8.5% in weld size, ~ 7.5% in peak temperature, ~ 16% in retained δ ferrite , ~ 17% in residual stress, and ~ 5% in distortion demonstrates the reliability of the developed model. A lower level of heat input (52 J/mm) allows the formation of a high amount of δ ferrite , which generates comparatively more compressive stress as a disparity in thermal expansion coefficient α Ni ∼ 1.6 α Cr aids in the reduction of residual stress.