Browsing by Author "Sun, SD"

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    Effect of laser clad repair on the fatigue behaviour of ultra-high strength AISI 4340 steel
    (Elsevier, 2014-06-12) Sun, SD; Liu, Q; Brandt, M; Luzin, V; Cottam, R; Janardhana, M; Clark, GA
    The fatigue behaviour of an ultra-high strength steel (>1800 MPa) was evaluated to assess the potential of using laser cladding as a repair tool for such steels in aeronautical structural applications. AISI 4340 and AerMet 100 steel powder were used to clad over a grind-out region in an AISI 4340 steel substrate using a 2.5 kW ND:YAG laser. Post-clad heat treatment (PCHT) was also investigated. Results showed very poor tensile properties and significantly reduced fatigue life of the AISI 4340 as-clad with a very high hardness and brittle fracture in the clad and HAZ zone. Residual stress results showed a compressive residual stress in the clad region and tensile residual stress in the HAZ. Changing the alloy of the clad layer to AerMet 100 steel, as well as applying a PCHT process, showed promising results as the fatigue life was improved from that of the grind-out substrate. © 2014, Elsevier B.V.
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    Microstructure, abrasive wear and corrosion characterisation of laser metal deposited Fe-30Cr-6Mo-10Ni-2.2C alloy
    (Elsevier B.V., 2019-11-15) Sun, SD; Fabijanic, D; Annasamy, M; Gallo, SC; Fordyce, I; Paradowska, AM; Leary, M; Easton, M; Brandt, M
    Advances in Laser Metal Deposition (LMD) provide technical opportunities such as the geometric restoration of worn components and custom surface coatings to enhance wear and corrosion resistance. Commercial applications include high Cr white cast iron (HCWCI) alloys for mining applications. In this study, a Fe-2.2C-30Cr-10Ni-6Mo alloy was deposited on mild steel substrates to characterise the effect of the LMD process, and a subsequent 1030 °C/4 h s heat treatment, on the microstructure, corrosion behaviour, and abrasive wear behaviour. The LMD microstructure consisted of fine eutectic Cr enriched M7C3 and Mo enriched M2C carbides in a γ-Fe matrix. This led to good abrasive wear and corrosion properties. The post heat treatment had an adverse effect on both the abrasion and corrosion resistance of this alloy, primarily due to the transformation of M7C3 to softer M23C6 carbides, and Cr depletion in the matrix. © 2019 Elsevier B.V.