This paper deals with submerged arc and electroslag strip cladding

of various past and present duplex stainless steels. The cladding processes are first depicted with their main advantages and disadvantages, the specificities of the fluxes and their main fields of utilisation. The most widespread strip/flux couples are briefly summarised.

Development work on duplex stainless steel materials started more than ten years ago, as soon as strips of suitable dimensions (e.g. 60´ 0.5mm) were made available for welding. From this time onwards, the cladding development programme undertaken by SOUDOMETAL has reflected the rapid evolution of the duplex family, from type 23 Cr-4Ni to type 25Cr – 6Ni – 3Mo – Cu, the latter being the most advanced step towards the super-duplex family.

The second part of the paper reviews consequently the main properties of strips, fluxes and weld metals of the various duplex grades which were developed over the last years.

Following characteristics are given:

– chemical analyses and microstructures;

– mechanical properties, such as reduced Charpy-V impact values and bending tests;

– corrosion resistance properties, such as pitting corrosion resistance (ASTM G48-A) and intercrystaline corrosion resistance (ASTM A262-C and A262-B)

Turning to the present situation of the market, it is first pointed out that no real attempt has been made by steel makers to produce super duplex strips due to the problems their hot workability arise. Therefore the development aiming at producing modern duplex stainless steels (i.e. 22Cr with a PRE ³ 35 or 25Cr with a PRE ³ 40) has to rely on fluxes. Addition of alloying elements in both submerged arc and electroslag fluxes in combination with the nowadays classic 22 to 23Cr – 6 to 9Ni – 3Mo (N) type strips allows to meet some of the most stringent specifications. This third part of the paper describes the properties of such welding couples.

Finally, as a conclusion, future developments in the field of cladding involving super duplex strips are anticipated.