ALLOYING VARIANTS INCREASING THE CORROSIO N-RESISTANCE OF WEAR-RESISTANT DUPLEX STAINLESS-STEELS

Due to their good corrosion properties, duplex stainless steels are us ed in many fields of chemical industry as well as power stations, mari ne and environmental engineering. Precipitation-hardened variants and alloys with slightly increased carbon content are avail able for handl ing media causing simultaneous corrosion and wear. This: improvement i n wear properties, on the other hand, reduces their corrosion resistan ce and thus limits their actual fields of applications. Also, the wear resistance achieved by these steels is far inferior to that of white iron, which, however, can only be used in water with close-to-neutral pH-value. So far, handling chemically aggressive media either entailed short service lives or required expensive special materials. Many dev elopment activities are therefore aimed at improving the combination o f tribological and electrochemical properties of duplex stainless stee ls. Different chemical compositions and types of hard phases result in varying corrosion and wear properties which are described on the basi s of a test melt and a new-developed alloy.