1970 Volume 56 Issue 2 Pages 285-299
The effect of Mo, Nb, Y, Ce, Zr and V on the high temperature properties of 10M6N type alloys and the grain boundary reaction (G. B. R.) occurred in this type alloys were examined.
Results obtained are as follows:
1) Addition of Nb causes such effects as (a) refinement of grain size, (b) increase of hardness in solution, (c) increase of tensile strength and deformation resistance at high temperatures, (d) suppression of age hardening accompanying the grain boundary reaction, (e) improvement of the properties against softening, (f) improvement of creep rupture time and elongation and so on. These are mutually related.(F) is chiefly due to (d) and (e), and also is considered to be partially due to the dispersion strengthening with Nb (C, N), from (b) and (c).
2) The improvement of creep rupture time by addition of Mo is due to (a) solution strengthening, (b) improvement of creep rupture elongation by strengthening in grain boundary.
3) G.B.R. tends to occur at a tripple point and also at the regions where two twins meet each other or where a grain and a twin meet each other. G. B. R. is accelerated by stress.
4) Addition of Y and Ce to 10M6N alloy and that of Zr and V to 10M6NB alloy do not remarkably im-prove the creep rupture properties of these alloys.