Materials performance · 1997 · 10 citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceCorrosion ScienceMetallic MaterialsMetallurgyAlloysCorrosion EvaluationCorrosion Of SteelsMetalsStainless SteelsSteel MaterialsFerritic Stainless SteelsFerritic Steel CorrosionHeat-affected Zone CorrosionHeat-affected Zone SensitizationIntergranular Corrosion TestingSteel Heat-affected ZoneSurface Quality ImprovementWeldability Of Alloys
Type 409 (UNS S40900) ferritic stainless steel, used widely in automotive exhaust systems, can be subject to intergranular corrosion (IGC) of weld heat-affected zones (HAZ), even though ASTM stabilization requirements (Ti = 6 {times} C) are met. A boiling Cu/6% CuSO{sub 4}/0.5% H{sub 2}SO{sub 4} test is shown to be appropriate for detecting IGC of welds and HAZ. This test was used to establish stabilization requirements for type 409, whether dual-stabilized with Ti + Nb or singly stabilized with Ti alone. It was found that the stabilization requirement should be Ti + Nb {ge} 0.08 + 8 (C + N). Benefits of dual stabilization include improved surface quality and formability without sacrifice of mechanical properties or weldability.