Lavorazione Duplex / SuperDuplex

Duplex stainless steels are a family of grades combining good corrosion resistance with high strength and ease of fabrication. Their physical properties are between those of the austenitic and ferritic stainless steels but tend to be closer to those of the ferritics and to carbon steel. The chloride pitting and crevice corrosion resistance of the duplex stainless steels is a function of chromium, molybdenum, tungsten, and nitrogen content. It may be similar to that of Type 316 or range above that of the sea water stainless steels such as the 6% Mo austenitic stainless steels. All the duplex stainless steels have chloride stress corrosion cracking resistance significantly greater than that of the 300-series austenitic stainless steels. They all provide significantly greater strength than the austenitic grades while exhibiting good ductility and toughness.
There are many similarities in the fabrication of austenitic and duplex stainless steels but there are important differences. The high alloy content and the high strength of the duplex grades require some changes in fabrication practice. This manual is for fabricators and for end users with fabrication responsibility. It presents, in a single source, practical information for the successful fabrication of duplex stainless steels. This publication assumes the reader already has experience with the fabrication of stainless steels; therefore, it provides data comparing the properties and fabrication practices of duplex stainless steels to those of the 300-series austenitic stainless steels and to carbon steel. The fabrication of duplex stainless steels is different but not difficult.

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