Undvikande av skadliga nitrider i duplexa rostfria stål

Important results from the project

The purpose of the SuperAVON project was to create a holistic view of nitride formation in conjunction with rapid cooling of duplex stainless steels. This has been done by to study and model the conditions for nitride formation, effect on properties and practical aspects such as material qualification. The most important deliverables from the project are: i) DICTRA-based model that predicts the occurrence of nitrides ii) property data for nitride-containing material iii) feasibility study of a cross-weld test to study the influence of different welding parameters in a simple way.

Expected long term effects

The project has delivered a significantly increased knowledge of nitride formation in conjuction with welding operations which has been disseminated by reports and a workshop. The DICTRA-based model that has been developed is expected to be used in various ways to create industrial value. For instance implementation in the tool developed within the, also Vinnova-financed Project, Duweldtool would allow end-users to benefit from the develop model without modelling expertise. Property-data shows the extent of property-degradation due to nitrides which can be used in e.g. dimensioning.

Approach and implementation

The project has been formulated around a large number of experiments of different types: - Detailed studies of the sensitive heat-affected zone adjacent to the weld via thorough studies in dilatometer and Gleeble. Metallographic investigations, property testing and model development have been done with respect to these materials. - Simulation of solution annealing within and beyond the NORSOK standard with the aim to evaluate material qualification criteria. - Welding experiments with the aim to develop a method for quick optimization of welding parameters