Laser cladding of austenitic stainless steel using NiTi strips for resisting cavitation erosion

K. Y. Chiu, F. T. Cheng, Hau Chung Man

Research output: Journal article publicationJournal articleAcademic researchpeer-review

46 Citations (Scopus)

Abstract

Being part of a larger project on using different forms of nickel titanium (NiTi) in the surface modification of stainless steel for enhancing cavitation erosion resistance, the present study employs NiTi strips as the cladding material. Our previous study shows that laser surfacing using NiTi powder can significantly increase the cavitation erosion resistance of AISI 316 L stainless steel [K.Y. Chiu, F.T. Cheng, H.C. Man, Mater. Sci. Eng. A 392 (2005) 348-358]. However, from an engineering point of view, NiTi strips are more attractive than powder because NiTi powder is very expensive due to high production cost. In the present study, NiTi strips were preplaced on AISI 316 L samples and remelted using a high-power CW Nd:YAG laser to form a clad layer. To lower the dilution due to the substrate material, samples doubly clad with NiTi were prepared. The volume dilution ratio in the singly clad sample was high, being in the range of 13-30% depending on the processing parameters, while that of the doubly clad sample was reduced to below 10%. Analysis by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffractometry (XRD) reveals that the clad layer is composed of a NiTi B2 based matrix together with fine precipitates of a tetragonal structure. Vickers indentation shows a tough cladding/substrate interface. The microhardness of the clad layer is increased from 200 HV of the substrate to about 750 HV due to the dissolution of elements like Fe, Cr and N in the matrix. Nanoindentation tests record a recovery ratio near to that of bulk NiTi, a result attributable to a relatively low dilution. The cavitation erosion resistance of the doubly clad samples is higher than that of 316-NiTi-powder (samples laser-surfaced with NiTi powder) and approaches that of NiTi plate. The high erosion resistance is attributed to a high hardness, high indentation recovery ratio and the absence of cracks or pores.
Original languageEnglish
Pages (from-to)126-134
Number of pages9
JournalMaterials Science and Engineering A
Volume402
Issue number1-2
DOIs
Publication statusPublished - 15 Aug 2005

Keywords

  • AISI 316L stainless steel
  • Cavitation erosion
  • Indentation properties
  • Laser cladding
  • NiTi
  • Strip material

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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