Alloy for high temperature tooling applications

Abstract

Thermal fatigue is the predominant mechanism that limits the service life of dies in semi-solid forming of steels since the feedstock to be shaped has a paste-like character. A novel alloy, more resistant to these conditions than any other alloy, has been developed. Eutectic carbides in Stellite alloys are replaced in this novel alloy with molybdenum-rich intermetallic compound particles between dendrites. This novel alloy offers at least 3 times longer service life with respect to Stellite 6 alloy that has been tested under conditions that mimic the steel semi-solid forming process and has been identified as the most suitable. The exceptional performance of the novel alloy is attributed to its outstanding resistance to oxidation and to softening at elevated temperatures and to its cobalt based matrix free from the hard and brittle carbides that have a negative impact on crack growth process.

1 . A cobalt based alloy with no carbon and 9-15 wt % iron in its chemical composition. 
     
     
         2 . An alloy according to  claim 1 , with a ferritic dendritic matrix phase and molybdenum-rich intermetallic particles at dendrite boundaries. 
     
     
         3 . An alloy according to  claim 1 , the extent of softening after 5000 cycles in thermal fatigue test of which, is less than 15%. 
     
     
         4 . An alloy according to  claim 1 , containing 0.72 wt % Si, 1.58 wt % Mn, 29.22 wt % Cr, 5.50 wt % Mo, 3.77 wt % Ni, wt % 11.50 Fe, the balance being Co.