Development of niobium bearing high carbon steel sheet for knitting needles

Eiji Tsuchiya, Yuta Matsumura, Yoshihiro Hosoya, Yuka Miyamoto, Takashi Kobayashi, Kazuhiro Seto, Keiko Tomura, Koji Inoue, Yasuyoshi Nagai

Research output: Contribution to journalArticle

Abstract

The effect of Nb addition of less than 0.05 mass% on the quenching and tempering behavior of spheroidized eutectoid steel, which has usually being applied to knitting needles, was investigated. The results obtained are as follows. 1) Hardenability upon brief heating was markedly improved by 0.01 mass% Nb addition. 2) Both quenching elongation and its standard deviation decreased with 0.01 mass% Nb addition compared with those of Nb-free steel. 3) While hardly any effect of Nb addition on the hardness was observed during low-temperature tempering, not only the impact toughness but also the fatigue durability was improved by 0.01 mass% Nb addition. 4) Atom probe tomography (APT) analyses revealed that the precipitation of carbon in solution directly resulted in the formation of ϵ- and/or 0-carbides with carbon contents of around 25 at% without the formation of clusters with 10-15 at% C upon the addition of a trace amount of Nb. 5) For the same P content, the average bulk concentration of P in the martensite phase markedly increased with the addition of up to 0.05 mass% Nb. 6) Regarding the optimum Nb content of 0.01 mass% for various mechanical properties upon the low-temperature tempering of martensite, it is considered that the mechanical properties are dominated by the balance between the positive effect of promoting carbide precipitation during low-temperature tempering by Nb addition and the negative effect of deteriorating the toughness with increasing bulk concentration of P in the martensitic phase upon the addition of more than 0.02 mass% Nb.

Original languageEnglish
Pages (from-to)1052-1062
Number of pages11
JournalIsij International
Volume60
Issue number5
DOIs
Publication statusPublished - 2020

Keywords

  • Atom probe tomography
  • Hardenability
  • High-carbon steel
  • Hypereutectoid steel
  • Low-temperature tempering
  • Martensite
  • Nb-bearing steel

ASJC Scopus subject areas

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

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  • Cite this

    Tsuchiya, E., Matsumura, Y., Hosoya, Y., Miyamoto, Y., Kobayashi, T., Seto, K., Tomura, K., Inoue, K., & Nagai, Y. (2020). Development of niobium bearing high carbon steel sheet for knitting needles. Isij International, 60(5), 1052-1062. https://doi.org/10.2355/isijinternational.ISIJINT-2019-084