Study of High Manganese Heat Resisting Steels

Abstract

In order to acquire the economical, easy-to-forge alloy, having an excellent creep rupture life, various kinds of alloys were prepared. That is, N-155 alloys with one part of Nickel and Iron N-155 alloy, replaced by Manganese and Chromium respectively, the ones with one part of Cobalt replaced by Chromium and the ones containing various amounts of Chromium, Nickel, Molybdenum, Tungsten, Niobium, Nitrogen etc, with Cobalt totally eliminated.
The effects of these elements on the high temperature properties were tested.
Results obtained are as follows.
The alloys containing γ+α phases showed a more remarkable age hardening property and a considerably poorer creep rupture life at 700°C than the ones having γ single phase.
The stable γ phase was found to be the indispensable condition for acquiring an austenite steel having an excellent creep rupture strength.
In 6% Nickel+10% Manganese type alloys containing no Cobalt, the stable γ phase could be obtained if the Nitrogen content was increased up to about 0.8%. The residual alloying composition showing the maximum creep rupture life in this type alloys was about 20% Chromium, 2.5% Tungsten, 2% Molybdenum, 1% Niobium, 0.23% Carbon, and the creep rupture life of the alloy having the above mentioned composition was superior to that of N-155 alloy. Furthermore, this alloy was easily forged and proved economical, it was named 10M6N alloy.