Control of cementite precipitation in lath martensite by rapid heating and tempering

T. Furuhara, K. Kobayashi, T. Maki

Research output: Contribution to journalArticle

79 Citations (Scopus)

Abstract

Lath martensite structures, tempered at various temperatures (723-923 K) were studied by changing heating rates (2 K/s to 1 000 K/s) to the tempering temperature in an alloy steel for machine structural use (SCM435; Fe-0.35C-0.24Si-0.77Mn-1.05Cr-0.17Mo). Hardness of the rapidly heated (at 100 K/s or 1 000 K/s) specimen is larger than that of the slowly heated (at 2 K/s) specimen when tempering temperature and time are the same. Cementite precipitates are formed on high-angle boundaries (prior austenite grain boundary, block and packet boundaries) as well as within laths and at low-angle boundaries (lath boundaries) by tempering. TEM observation has revealed that finer cementite is dispersed more uniformly in the rapidly heated specimen than in the slowly heated specimen. It is considered that the temperature where cementite precipitation starts is raised by increasing the heating rate to tempering temperature, resulting in a higher nucleation rate and a finer dispersion of cementite.

Original languageEnglish
Pages (from-to)1937-1944
Number of pages8
JournalIsij International
Volume44
Issue number11
DOIs
Publication statusPublished - 2004 Jan 1
Externally publishedYes

Keywords

  • Cementite
  • Dislocation
  • Ductility
  • Martensite
  • Precipitation
  • Rapid heating
  • Recovery
  • Steel
  • Strength
  • Tempering

ASJC Scopus subject areas

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

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