Effect of processing conditions on the corrosion performance of laser surface-melted AISI 440C martensic stainless steel

C. T. Kwok, K. H. Lo, F. T. Cheng, Hau Chung Man

Research output: Journal article publicationJournal articleAcademic researchpeer-review

76 Citations (Scopus)

Abstract

Laser surface melting of AISI 440C martensitic stainless steel was achieved using a 2.5-kW continuous wave Nd:YAG laser. The pitting corrosion behavior of laser surface-melted specimens processed under different processing conditions in 3.5% NaCl solution at 23 °C was studied by potentiodynamic polarization technique. The corrosion resistance of all laser surface-melted specimens was significantly improved, as evidenced by a shift from active corrosion to passivity, a wide passive range and a low passive current density. The pitting potential of the laser surface-melted specimens P08-440C-25 (laser powers = 0.8 kW, scanning speed = 25 mm/s) and P12-440C-25 (laser power = 1.2 kW, scanning speed = 25 mm/s) was increased to 260 and 200 mV (SCE), respectively, and was much higher than that of the conventionally heat-treated AISI 440C. The pitting corrosion characteristics of the laser surface-melted specimens were strongly dependent on the processing conditions which resulted in different microstructures. The enhanced corrosion resistance was attributed to the dissolution or refinement of carbide particles and the presence of retained austenite. The amount of carbides in the melt layer, which indirectly determine the Cr content in solid solution and hence, the corrosion resistance, was related to the amount of C remaining in solid solution and to decarburization. The pit morphology of the laser surface-melted specimen was also studied.
Original languageEnglish
Pages (from-to)221-230
Number of pages10
JournalSurface and Coatings Technology
Volume166
Issue number2-3
DOIs
Publication statusPublished - 24 Mar 2003

Keywords

  • Laser surface melting
  • Martensic stainless steel
  • Nd
  • Pitting corrosion
  • YAG laser

ASJC Scopus subject areas

  • Surfaces, Coatings and Films
  • Condensed Matter Physics
  • Surfaces and Interfaces

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