Bead Weld Cold Plastic Deformation Effects on AISI 409 Ferritic Stainless Steel, Ti and Nb Stabilized
The automotive industry has been increasing stainless steel consumption daily. Some important parts of a car should keep using carbon steel, however, the exhaust system must use stainless steel tubes since the gas from engine cannot corrode those tubes, avoiding catalytic conversor contamination. Among stainless steel groups, ferritic has been choosing due to costs and strong high temperatures resistance. This report starts studying ferritic stainless steel welded tubes mechanical properties (ABNT 409 stabilized), raw material for exhaust systems. Some welded tubes have been produced with internal bead rollers, to compare, afterwards, with tubes which were produced without bead hardening. The results shows that hardening induced by bead rolling causes material elongation reduction, that could lead problems on the tube forming operation during exhaust system production. Those materials have been analyzed by optical and electronic microscopy, Vickers micro hardness and tensile test.