Detrimental Cr-rich Phases Precipitation on SAF 2205 Duplex Stainless Steels Welds After Heat Treatment

Abstract The austeno-ferritic Stainless Steels are commonly employed in various applications requiring structural performances with enhanced corrosion resistance. Their characteristics can be worsened if the material is exposed to thermal cycles, since the high-temperature decomposition of ferrite causes the formation of detrimental secondary phases. The Submerged Arc Welding (SAW) process is currently adopted for joining DSS owing to its relatively simple execution, cost savings, and using molten slag and granular flux from protecting the seam of atmospheric gases. However, since it produces high contents of δ-ferrite in the heat affected zone and low content of γ-austenite in the weld, high-Ni filler materials must be employed, to avoid excessive ferritization of the joint. The present work is aimed to study the effect of 3 and 6 hours isothermal heat treatments at 850°C and 900°C in a SAF 2205 DSS welded joint in terms of phases precipitation. The results showed the presence of σ-phase at any time-temperature combination, precipitating at the δ/γ interphases and often accompanied by the presence of χ-phase. However, certain differences in secondary phases amounts were revealed among the different zones constituting the joint, ascribable both to peculiar elements partitioning and to the different morphology pertaining to each microstructure

Effect of gas tungsten arc welded 308 and 409 stainless steels on their mechanical properties

Stainless steels (SS) in automobile sector were previously incorporated mainly due to their decorativeapplications. Nowadays, their functional and specific characteristics make them more required and employedin this sector. Especially attention from automotive manufacturers has been paid in order to improve the engineefficiency and reduce weight of the vehicle, stainless steels result to be enabled due to their high strengthmechanical characteristics, energy absorption capability, fatigue and corrosion resistance; besides theirductility which is traduced to an easy manufacturability. When welding is applied some of their characteristicsmay be affected and could decrease their mechanical properties. In attempt to avoid these circumstances,welding experimental practices must be carried out. In this study plates of 308 austenitic and 409 ferriticstainless steels were welded by Gas Tungsten Arc Welding process with different current values in order toget their mechanical properties behavior. Tensile tests were performed, it results that for austenitic stainlesssteels welds all failed in the fusion zone presenting ductile behavior; however, for ferritic stainless steels brittlefracture was observed. The maximum value of hardness for 308 austenitic SS was founded in the base metal,instead for 409 ferritic SS was reached at the heat affected zone.This study can be a practical guide in the selection of adequate joining methods in order to determine the moreefficient to use in structural automotive industry

Acciaio inossidabile effect of gas tungsten arc welded 308 and 409 stainless steels on their mechanical properties

Stainless steels (SS