Effect of Cu addition on formation of reversed austenite and hardness in 9% Ni steels

Nobuo Nakada, Toru Yamashita, Junaidi Syarif, Toshihiro Tsuchiyama, Setsuo Takaki

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Copper (Cu) was added to a cryogenic 9% Ni steel as an alloying element for improving strength and controlling microstructure, and then the softening behavior and microstructural development during tempering were investigated in the 9% Ni steels with various amounts of Cu. Hardness of the specimens decreased with an increase in tempering time owing to recovery of martensite. However, the addition of Cu more than 1% significantly retarded the softening. In particular, the steels containing 2% Cu or more exhibited clear age hardening phenomena after tempering at 873K for 1.8 ks. The retardation of softening by Cu is found to be due to precipitation of fine Cu particles within martensite matrix. On the other hand, Cu addition promoted the formation of reversed austenite at tempering temperature, thus the volume fraction of the reversed austenite became much larger in a 3% Cu bearing steel than in a Cu free 9% Ni steel under a same tempering condition. Chemical analysis using XEDS revealed that not only Ni but also Cu concentrate into the reversed austenite and make the austenite more stable in the Cu bearing steel than in the Cu free steel. As a result, the hardness of Cu bearing 9% Ni steels was found to be estimated by the law of mixture of each hardness in martensite and reversed austenite.

Original languageEnglish
Pages (from-to)1050-1056
Number of pages7
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume89
Issue number10
Publication statusPublished - Oct 2003
Externally publishedYes

Fingerprint

Steel
austenite
Austenite
hardness
Hardness
tempering
steels
Tempering
Bearings (structural)
martensite
Martensite
softening
precipitation hardening
Age hardening
Alloying elements
chemical analysis
Cryogenics
alloying
cryogenics
Copper

Keywords

  • ε-copper reversed austenite
  • 9% Ni steel
  • Law of mixture
  • Martensite
  • Microstructure
  • Precipitation hardening

ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Effect of Cu addition on formation of reversed austenite and hardness in 9% Ni steels. / Nakada, Nobuo; Yamashita, Toru; Syarif, Junaidi; Tsuchiyama, Toshihiro; Takaki, Setsuo.

In: Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan, Vol. 89, No. 10, 10.2003, p. 1050-1056.

Research output: Contribution to journalArticle

Nakada, N, Yamashita, T, Syarif, J, Tsuchiyama, T & Takaki, S 2003, 'Effect of Cu addition on formation of reversed austenite and hardness in 9% Ni steels', Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan, vol. 89, no. 10, pp. 1050-1056.
Nakada, Nobuo ; Yamashita, Toru ; Syarif, Junaidi ; Tsuchiyama, Toshihiro ; Takaki, Setsuo. / Effect of Cu addition on formation of reversed austenite and hardness in 9% Ni steels. In: Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan. 2003 ; Vol. 89, No. 10. pp. 1050-1056.
@article{ce8b7f46b00243619b065eedb1372f0b,
title = "Effect of Cu addition on formation of reversed austenite and hardness in 9{\%} Ni steels",
abstract = "Copper (Cu) was added to a cryogenic 9{\%} Ni steel as an alloying element for improving strength and controlling microstructure, and then the softening behavior and microstructural development during tempering were investigated in the 9{\%} Ni steels with various amounts of Cu. Hardness of the specimens decreased with an increase in tempering time owing to recovery of martensite. However, the addition of Cu more than 1{\%} significantly retarded the softening. In particular, the steels containing 2{\%} Cu or more exhibited clear age hardening phenomena after tempering at 873K for 1.8 ks. The retardation of softening by Cu is found to be due to precipitation of fine Cu particles within martensite matrix. On the other hand, Cu addition promoted the formation of reversed austenite at tempering temperature, thus the volume fraction of the reversed austenite became much larger in a 3{\%} Cu bearing steel than in a Cu free 9{\%} Ni steel under a same tempering condition. Chemical analysis using XEDS revealed that not only Ni but also Cu concentrate into the reversed austenite and make the austenite more stable in the Cu bearing steel than in the Cu free steel. As a result, the hardness of Cu bearing 9{\%} Ni steels was found to be estimated by the law of mixture of each hardness in martensite and reversed austenite.",
keywords = "ε-copper reversed austenite, 9{\%} Ni steel, Law of mixture, Martensite, Microstructure, Precipitation hardening",
author = "Nobuo Nakada and Toru Yamashita and Junaidi Syarif and Toshihiro Tsuchiyama and Setsuo Takaki",
year = "2003",
month = "10",
language = "English",
volume = "89",
pages = "1050--1056",
journal = "Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan",
issn = "0021-1575",
publisher = "Iron and Steel Institute of Japan",
number = "10",

}

TY - JOUR

T1 - Effect of Cu addition on formation of reversed austenite and hardness in 9% Ni steels

AU - Nakada, Nobuo

AU - Yamashita, Toru

AU - Syarif, Junaidi

AU - Tsuchiyama, Toshihiro

AU - Takaki, Setsuo

PY - 2003/10

Y1 - 2003/10

N2 - Copper (Cu) was added to a cryogenic 9% Ni steel as an alloying element for improving strength and controlling microstructure, and then the softening behavior and microstructural development during tempering were investigated in the 9% Ni steels with various amounts of Cu. Hardness of the specimens decreased with an increase in tempering time owing to recovery of martensite. However, the addition of Cu more than 1% significantly retarded the softening. In particular, the steels containing 2% Cu or more exhibited clear age hardening phenomena after tempering at 873K for 1.8 ks. The retardation of softening by Cu is found to be due to precipitation of fine Cu particles within martensite matrix. On the other hand, Cu addition promoted the formation of reversed austenite at tempering temperature, thus the volume fraction of the reversed austenite became much larger in a 3% Cu bearing steel than in a Cu free 9% Ni steel under a same tempering condition. Chemical analysis using XEDS revealed that not only Ni but also Cu concentrate into the reversed austenite and make the austenite more stable in the Cu bearing steel than in the Cu free steel. As a result, the hardness of Cu bearing 9% Ni steels was found to be estimated by the law of mixture of each hardness in martensite and reversed austenite.

AB - Copper (Cu) was added to a cryogenic 9% Ni steel as an alloying element for improving strength and controlling microstructure, and then the softening behavior and microstructural development during tempering were investigated in the 9% Ni steels with various amounts of Cu. Hardness of the specimens decreased with an increase in tempering time owing to recovery of martensite. However, the addition of Cu more than 1% significantly retarded the softening. In particular, the steels containing 2% Cu or more exhibited clear age hardening phenomena after tempering at 873K for 1.8 ks. The retardation of softening by Cu is found to be due to precipitation of fine Cu particles within martensite matrix. On the other hand, Cu addition promoted the formation of reversed austenite at tempering temperature, thus the volume fraction of the reversed austenite became much larger in a 3% Cu bearing steel than in a Cu free 9% Ni steel under a same tempering condition. Chemical analysis using XEDS revealed that not only Ni but also Cu concentrate into the reversed austenite and make the austenite more stable in the Cu bearing steel than in the Cu free steel. As a result, the hardness of Cu bearing 9% Ni steels was found to be estimated by the law of mixture of each hardness in martensite and reversed austenite.

KW - ε-copper reversed austenite

KW - 9% Ni steel

KW - Law of mixture

KW - Martensite

KW - Microstructure

KW - Precipitation hardening

UR - http://www.scopus.com/inward/record.url?scp=0344099367&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0344099367&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0344099367

VL - 89

SP - 1050

EP - 1056

JO - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan

JF - Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan

SN - 0021-1575

IS - 10

ER -