Characterization of the inhomogeneous distribution of light elements in ferritic heat-resistant steels by secondary ion mass spectrometry

Shigeru Suzuki, Rie Shishido, Tomohito Tanaka, Fujio Abe

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The addition of a small amount of boron and nitrogen is known to improve the creep strength and life of ferritic heat-resistant steels. These light elements are thought to be distributed in the microstructures in a complicated manner during the heat treatment and creep of these steels. In order to understand the influence of the light elements on the mechanical properties of ferritic heat-resistant steels, a microscopic distribution analysis of the light elements is of importance. In this study, two types of secondary ion mass spectrometry (SIMS) methods were used to investigate the measurement conditions for analyzing secondary ions derived from boron and nitrogen in steels. In dynamic SIMS with a quadrupole analyzer, boron in the samples was effectively detected as BO2- ions under irradiation with primary O2+ ions. From the timeof-flight (ToF) SIMS using a focused primary Bi32+ ion beam coupled with the exposure of the sample to a low partial pressure of oxygen, it was suggested that boron is enriched in M23C6 carbides in the steels and it may be, more or less, segregated at prior austenite grain boundaries with a moderate amount of nitrogen during normalizing. It was also demonstrated that nitrogen is precipitated as boron nitride in steels containing an excess amount of boron and nitrogen. The characteristics of the distribution of boron and nitrogen in the steels are discussed on the basis of the thermodynamic properties of these elements in the steels.

Original languageEnglish
Pages (from-to)885-892
Number of pages8
JournalIsij International
Volume54
Issue number4
DOIs
Publication statusPublished - 2014

Keywords

  • Boron
  • Grain boundary
  • Precipitation
  • Secondary ion mass spectrometry
  • Segregation

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'Characterization of the inhomogeneous distribution of light elements in ferritic heat-resistant steels by secondary ion mass spectrometry'. Together they form a unique fingerprint.

  • Cite this