Prediction of percentage of ferrite as a function of heat input in robotic gas metal arc welding of duplex stainless steel SAF 2205 Welds

Dual phase duplex stainless steels with ferrite and austenite as [art of their microstructure have shown an outstanding strength and corrosion resistance despite of the aggressive and hostile environments they can be subjected to. In the last years a worldwide rapid growth demand and consumption of duplex stainless steel, particularly in petrochemical, marine, power plant, food industry and other engineering applications have taken place especially where welding process were required. Joining of duplex alloys is a challenging task, due to the formation of embrittling precipitates and metallurgical changes they go through during the welding process. generally, the quality of a weld joint is strongly influenced by the welding conditions and imbalance phase ratio between austenite and ferrite, these factors leads to solidification cracking, corrosion susceptibility, and lower ductility. To achieve high quality welds mathematical models have been developed in order to predict the ideal bead geometry to achieve optimal mechanical properties. This paper focuses on determining the percentage if ferrite in GMAW welds of duplex stainless steel SAF 2205. As experimental model for the prediction of weld bead geometry was developed and applied. The values of weld penetration and reinforcement areas were calculated using statistical approach and the amount of ferrite in the duplex stainless steel welds were determined applying the rule of mixtrure and and the Schaeffler diagram. These predicted values of ferrite were later on compared with the experimental and values obtained through chemical. The results indicate 0.7% of error between experimental and predicted values of ferite when using heat inputs higher than 0.9 kJ/mm.