Schmiedt-Kalenborn Anke, Lingnau Lars Andree, Manka Matthias, Tillmann Wolfgang, Walther Frank
Department of Materials Test Engineering (WPT), TU Dortmund University, Baroper Str. 303, D-44227 Dortmund, Germany.
Institute of Materials Engineering (LWT), TU Dortmund University, Leonhard-Euler-Str. 2, D-44227 Dortmund, Germany.
Materials (Basel). 2019 Mar 29;12(7):1040. doi: 10.3390/ma12071040.
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.
由于在役的钎焊不锈钢部件通常必须在腐蚀性环境中承受循环载荷，因此必须对钎焊接头的腐蚀疲劳性能进行表征。对于钎焊接头而言，在腐蚀性介质中进行与实际应用相关的腐蚀疲劳试验极为罕见，并且循环变形曲线几乎未得到研究。在本研究中，按照VDA 230 - 214标准，在空气和合成废气冷凝物K2.2中对钎焊的AISI 304L/BAu - 4接头进行了疲劳试验。将钎焊接头的疲劳行为与奥氏体母材的性能进行了比较。在疲劳和腐蚀疲劳试验中应用了应变、电、磁、温度和电化学测量技术，以表征钎焊接头的循环变形和损伤行为。结果发现，由于叠加的腐蚀性载荷，在2×10⁶次循环时397 MPa的疲劳强度降低至51%。对于在原始状态和预腐蚀状态下试样的腐蚀疲劳载荷和疲劳载荷，确定了与微观结构相关的不同损伤机制。这些研究表明了腐蚀性环境对钎焊不锈钢接头力学性能的重要作用。
