日本金属学会誌

J. Japan Inst. Metals, Vol. 31, No. 7 (1967),
pp. 850-854

Effect of Al upon Age-Hardening of 17-7 PH Steel, and Nature of its Age-Hardening (On the Nature of Age-Hardening of 17-7 PH Steel, II)

Natsuo Yukawa1, Masayoshi Mizutani2 and Hiroyasu Saka1

1Department of Metallurgy, Faculty of Engineering, Nagoya University, Nagoya
2Toyota Central Research and Development Laboratories Inc., Nagoya

Abstract:

In the previous paper, the phase changes in 17-7 PH steel were determined. In the present paper, the effect of Al upon its age-hardening characteristics was studied, and its nature was clarified.
The age-hardening of alloys free from δ(0∼1.2%Al) is enhanced markedly with Al content owing to an increase of α ' precipitates. In alloys with δ alone (>4%Al), however, α ' precipitates so rapidly that it cannot be suppressed even by water-quenching after solution treatment, and hence no appreciable age-hardening is observed on subsequent aging. Thus, the maximum hardening is obtained in alloys which consist of αM and a small amount of δ with about 1.5%Al corresponding to the Al content of the standard 17-7 PH steel. In commercial 17-7 PH steel with about 0.07%C, M23C6 carbide also precipitates from the matrix during aging, which, however, seems unlikely to be responsible for the age-hardening of this steel, because its amount is negligibly small.
Considering the results of the present and previous experiments, the remarkable age-hardening of 17-7 PH steel was attributed to the precipitation of α ' from αM.


(Received 1967/1/6)

Keywords:


PDF(Free)PDF (Free)     Table of ContentsTable of Contents

Please do not copy without permission.