Control of low temperature embrittlement in duplex stainless steels

Purpose and goal

The project has delivered experimental results, microstructure characterisation, models, new insights for manufacture and use of duplex stainless steels at the temperatures connected to the low temperature embrittlement phenomenon. New material & welds and new analysis & testing methods have been included in this project and also investigation on how to mitigate the low temperature embrittlement. Within the project two workshops have been organised to disseminate results from the project and this has led to a discussion about possibilities for a continuation on this topic.

Expected results and effects

The experimental results, mechanical properties versus time/temperature, are available for all project participants and can be used in discussions with customers as technical support. Methods for mitigating the consequences of low temperature embrittlement have successfully been tried out and the property and microstructure influence of short temperature spikes before and after ageing for long times studied. The project has produced new models and made new property results available and results & effect will contribute for Sweden to maintain the position in this area.

Planned approach and implementation

The project was divided into 3 phases and 7 deliverables. Phase 1 consisted of production of 13 welds for long-term heat treatments and evaluation of material from a previous project which had been heat treated at critical temperatures for 5.5 years. Phase 2 consisted of review of literature and procurement of models for mechanical properties such as hardness and toughness versus time and temperature. Phase 3 consisted of dissemination via seminars, writing of guidelines, technical reports and scientific papers; mandatory for the beam times granted within the project.