Abstract
It is a well known fact that ferritic stainless steels are more useful than austenitic stainless steels as the chemical plant materials used in sulphuric atmosphere.
We have made high temperatuse creep rupture tests on the mother plates, deposited metals and their welded joints of type 446 (25 Cr stainless steel) and Sicromal-12 (25Cr+ 1.5Si+1.6 Al stainless steel) that is known so far as the highest class material for ferritic steels.
The result can be summarised as follows :
(1)High temperature creep rupture strengths on the mother plate and deposited metal of type 446 are more or less superior than Sicromal-12.
(2)Creep rupture strengths of the welded joints show no difference in comparison with the respective mother plate.
(3)We consider that a-phase-that is specific characteristic on these materials-is an important factor to have an effect on the creep rupture strength, especially as Sicromal-12 remarkably forms more a-phase than type 446.
