Nitrogen supersaturation process in the AISI420 martensitic stainless steels by low temperature plasma nitriding

Abdelrahman Farghali, Tatsuhiko Aizawa

Research output: Contribution to journalReview article

10 Citations (Scopus)

Abstract

A high-density RF-DC plasma nitriding system was employed on AISI420-J2 martensitic stainless steel at 653 K, 673 K, and 693 K for 14.4 ks. Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and electron backscattered diffraction (EBSD) were utilized to make analysis and characterization of the nitrided layers. These layers with the thickness of 85 m from the surface was mainly nitrogen super-saturated with formation of nitrides at the vicinity of surface. The nitrogen content depth profile was nearly constant by 10 at% except for the gradual decrease from the maximum content by 30 at% at the surface and for the decay toward the nitriding front end. The lattice expansion by the strain of 1.6 % drove the phase transformation from the original martensite to austenite. High plastic straining following this elastic lattice expansion also caused the grain size refinement from the original size of 10 m down to 0.15 m.

Original languageEnglish
Pages (from-to)401-407
Number of pages7
JournalISIJ International
Volume58
Issue number3
DOIs
Publication statusPublished - 2018 Jan 1

Keywords

  • AISI 420-J2 martensitic stainless steel
  • Low-temperature plasma nitriding
  • Phase transformation

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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