How is 2205 Duplex Stainless Steel Impacted by Heat Treatment?

Post-Weld Heat Treatment

The most well-known and significant method for improving microstructure after welding is post-weld heat treatment (PWHT), which includes several elements such as heating temperature, holding time, cooling rate, and process atmosphere. Intermetallic precipitation, which depends on the presence of Cr, Mo, and C, is promoted by PWHT, incorrect annealing temperature, protective gas, and slow cooling rate. The PWHT of welds, in general, and DSS weldments, in particular, has been the subject of numerous investigations.

According to several studies, annealing should take place between 1000 and 1200 °C, followed by water quenching. Some studies stated that between 1050 and 1100 °C is the ideal annealing temperature for DSS without intermetallic precipitation. The annealing duration and cooling rate should be taken into account during PWHT. Many researchers have examined the impacts of solution annealing time and have found that lengthening the annealing period causes corrosion resistance to diminish.

 

The production of hazardous phases is caused by the slower cooling rate that occurs after solution treatment of welded joints, even though the cooling rate during PWHT is a significant cause for concern. The presence of intermetallic phases and the sigma phase, which is richer with Cr and Mo, make DSS steel more susceptible to embrittlement, which results in decreased mechanical qualities and low corrosion resistance.

To prevent the creation of hazardous phases, the PWHT technique must be followed appropriately. On the other hand, the right PWHT can increase the austenite volume fraction, which increases the corrosion resistance of the DSS weldments. This viewpoint emphasizes the significance of selecting the best PWHT settings. Only a few studies have been reported on the impact of heat treatment atmosphere on the microstructure of DSS welded joints.