Fatigue and Corrosion Fatigue Behaviour of Brazed Stainless Steel Joints AISI 304L/BAu-4 in Synthetic Exhaust Gas Condensate

• Main Authors: Anke Schmiedt-Kalenborn, Lars Andree Lingnau, Matthias Manka, Wolfgang Tillmann, Frank Walther
• Format: Article
• Language: English
• Published: MDPI AG 2019-03-01
• Series: Materials
• Subjects: brazed joint; AISI 304/BAu-4; fatigue; corrosion fatigue; synthetic exhaust gas condensate
• Online Access: https://www.mdpi.com/1996-1944/12/7/1040

As brazed stainless steel components in service often have to withstand cyclic loads in corrosive environments, the corrosion fatigue properties of brazed joints have to be characterised. Application-relevant corrosion fatigue tests in corrosive media are extremely rare for brazed joints and cyclic deformation curves are barely investigated. In this study, fatigue tests of brazed AISI 304L/BAu-4 joints were performed in air and synthetic exhaust gas condensate K2.2 according to VDA 230-214. The fatigue behaviour of the brazed joints was compared to properties of the austenitic base material. Strain, electrical, magnetic, temperature and electrochemical measurement techniques were applied within fatigue and corrosion fatigue tests to characterise the cyclic deformation and damage behaviour of the brazed joints. It was found that the fatigue strength of 397 MPa at 2 × 10⁶ cycles was reduced down to 51% due to the superimposed corrosive loading. Divergent microstructure-related damage mechanisms were identified for corrosion fatigue loadings and fatigue loadings of specimens in the as-received and pre-corroded conditions. The investigations demonstrate the important role of corrosive environments for the mechanical performance of brazed stainless steel joints.