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

Abstract

Stainless steels (SS) in automobile sector were previously incorporated mainly due to their decorative
applications. Nowadays, their functional and specific characteristics make them more required and employed
in this sector. Especially attention from automotive manufacturers has been paid in order to improve the engine
efficiency and reduce weight of the vehicle, stainless steels result to be enabled due to their high strength
mechanical characteristics, energy absorption capability, fatigue and corrosion resistance; besides their
ductility which is traduced to an easy manufacturability. When welding is applied some of their characteristics
may 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 ferritic
stainless steels were welded by Gas Tungsten Arc Welding process with different current values in order to
get their mechanical properties behavior. Tensile tests were performed, it results that for austenitic stainless
steels welds all failed in the fusion zone presenting ductile behavior; however, for ferritic stainless steels brittle
fracture 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 more
efficient to use in structural automotive industry.