Browsing by Author "Li, DX"

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    Residual stress measurements of lean duplex stainless steel welded sections
    (Elsevier, 2021-08-08) Li, DX; Paradowska, AM; Uy, B; Wang, J; Proust, G; Azad, SK; Huang, YR
    Lean duplex stainless steel (LDSS) has been increasingly utilised in engineering applications due to its excellent durability, corrosion resistance, as well as superior structural and economic benefits. Moreover, compared to cold-form sections, welded members have significant structural advantages, and thus, have been widely used in many engineering practices. However, as one of the key factors affecting the performance of structural components, residual stresses of LDSS welded sections have not been sufficiently investigated. Therefore, square and H-shaped LDSS welded sections were considered in the present experimental programme. Accurate measurements of the tensile and compressive residual stresses were conducted through the non-destructive neutron diffraction method. As LDSS is a dual-phase material, neutron diffraction measurement was repeated twice for each specimen to obtain the individual phase residual stresses (ferrite-phase, α and austenite-phase, γ). Hardness analysis, as well as microstructural characterisation using optical microscopy and electron backscatter diffraction (EBSD) were thereafter performed to ascertain the volume fraction of each phase, based on which the residual stresses along the direction of interest were successfully converted. According to the obtained experimental results, the authors recommended analytical models for the LDSS fabricated square sections and proposed new models for the H-sections, through which the residual stress distributions for welded LDSS sections can be accurately predicted. In addition, the recommended/proposed analytical models for LDSS sections were further compared with their counterparts previously developed for high-strength steel (HSS) and ultra-high-strength steel (UHSS) welded sections. © 2021 Elsevier Ltd
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    Residual stresses of box and I-shaped columns fabricated from S960 ultra-high-strength steel
    (Elsevier B. V., 2019-12-24) Li, DX; Paradowska, AM; Uy, B; Wang, J; Khan, M
    Ultra-high-strength steel (UHSS) with a nominal yield stress of 960 MPa is of significant interest for the design of heavily loaded compressive members, such as high-rise buildings, long-span bridges and large-scale infrastructure. However, the residual stresses induced by the fabrication process can be detrimental to the structural members. In particular, compressive residual stresses can result in premature buckling and the ultimate strength of fabricated columns will be reduced. To date, research pertaining to the distribution of the residual stresses for UHSS column is limited. An experimental program about the measurements of residual stress distributions for UHSS box and I-shaped columns is therefore presented herein. Measurements of residual stress were undertaken on two box and two I-shaped columns having various width-to-thickness ratios by using the non-destructive neutron diffraction method. The distributions of residual stress in three orthogonal directions for each specimen was measured. The influences of column width-to-thickness ratio on residual stress distributions were investigated and discussed. In addition, simplified analytical models for the box and I-shaped column were established to facilitate the buckling analysis for such UHSS columns. Comparisons of the residual stress distributions between the experimental results and analytical model demonstrated a good agreement and this model can be safely used for the fabricated high-strength-steel (HSS) and UHSS column. Crown Copyright © 2019 Published by Elsevier Ltd