Evaluation and Qualification of the Brazing of Stainless Steel Joints Employing Silver-Based Filler Metals for Application in Aircraft Pressurized Oxygen Systems

• Published in: Metallography, microstructure, and analysis Vol. 12; no. 3; pp. 433 - 443
• Main Authors: Siqueira, Lucas Oliveira, de Mello Picchi, Ivan Bezerra, Simões Andrade, André Luís, Torres López, Edwar Andrés, de Lima, Nathalia Bezerra, de Abreu Santos, Tiago Felipe
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2023; Springer Nature B.V
• Subjects: Brazed joints; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Cross-sections; Diamond pyramid hardness; Fillers; Materials Science; Metallic Materials; Nanotechnology; Oxyacetylene; Peer-Reviewed Paper; Shear strength; Silver; Solid solutions; Stainless steels; Steel plates; Strength testing; Structural Materials; Surfaces and Interfaces; Thin Films; Tin; Torch brazing; Standard qualification; Torch brazing; Stainless steel; Silver-based filler metal; Mechanical evaluation
• ISSN: 2192-9262; 2192-9270
• DOI: 10.1007/s13632-023-00955-1

The oxyacetylene torch brazing of stainless steel plates using silver-based filler metals (Ag–Cu–Zn–Sn) was investigated. Filler metals with silver quantities of 25%, 35%, and 45% were used to evaluate the influence of silver contents on the processing of joints. The brazed joints were evaluated in accordance with brazing qualification standards. Further, the number of pores from cross sections in different samples for each brazed joint condition was evaluated. The results revealed that the brazed joints exhibited pores, however, did not exceed the maximum percentage allowed in the same cross section. Scanning electron microscopy analysis revealed that the brazed joints are mainly composed of Ag solid solution, Cu solid solution and (Ag + Cu) eutectic microconstituent. Furthermore, the Vickers microhardness test indicated the presence of microstructural discontinuities in the joints 25 and 35 Ag. Finally, the shear strength testing revealed that the joint 45 Ag has a higher average performance.