Structural investigations of carburized alloy 800H

摘要

The effect of carburization on the impact strength and microstructure of the commercial Alloy 800H (Fe-32Ni-20Cr) has been investigated in the temperature range 20 - 800°C. The properties and microstructure of test pieces carburized at 850°C for up to 500 h in an argon - 10 volume % methane atmosphere and of specimens aged at 850°C in an inert atmosphere tor the same times were compared. Microstructural investigations by optical metallography, and transmission and scanning electron microscopy showed the details of the microstructure after ageing and carburization at 850°C. The results showed that ageing at 850°C reduced the impact strength in the range 20 - 800°C. With increasing degree of carburization, the impact strength was progressively reduced to around 50 J at a bulk carbon content of 0.6 wt %. Effects of carburization on the microstructure and mechanical properties of Alloy 800H are discussed.