While much work has been published about the modelling of steels in the as delivered condition, there are only few prediction systems applicable to welds, which may exhibit properties substantially different from those of the base metal.

This paper introduces a CLI prediction system of different properties of duplex and super duplex welds based upon extensive experimental data. Those data have been treated in order to obtain the best statistical relations with several experimental parameters. Existing models to calculate the cooling rate have also been used.

As this calculation process is time consuming, the use of a micro computer is essential. The overall time for calculation is that required to enter data concerning the plate and filler material compositions, welding conditions and when necessary post weld heat treatment.

The output data of the model are:

– microstructure of HAZ and weld metal (% ferrite, % secondary austenite, % austenite)

– maximum hardness in the HAZ and in the weld metal

– tensile strength of the weld metal

critical pitting temperature (ASTM G48A) for the weld and the parent material

The welding engineer can also estimate other potential risks for the duplex or super duplex weld such as excessive porosities formation or hydrogen embrittlement.

This prediction system that can be used to evaluate the properties of an existing weld but also help to define optimised welding conditions, parent or filler metal compositions and if necessary heat treatment to meet specific technical requirements of the weld.

Those aspects of the CLI prediction system are very useful not only to develop new base metal or filler materials compositions with attractive properties but also to help customers less familiar with duplex or super duplex welding to avoid to make mistakes.