A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Lalam, Sree Vardhan
- Microstructure and Strength of Al2O3 – EN24 Vacuum Brazed Joints
Authors
1 Naval Systems & Materials, NSTL Campus, Visakhapatnam – 530 027, IN
Source
Indian Welding Journal, Vol 47, No 3 (2014), Pagination: 1-11Abstract
In the present investigation, microstructural features and lap shear strength of vacuum brazed joints of polycrystalline alumina and low alloy steel EN24 were investigated. The joints were brazed in vacuum brazing furnace at 850°C by varying time using Ag26.7Cu4.5Ti (wt%) brazing alloy. The microstructure was characterized by optical microscope and scanning electron microscope (SEM). Qualitative and quantitative phase analysis was carried out from SEM Energy Dispersive Spectroscopy (EDS), Electron Probe Micro Analysis (EPMA) and X-Ray Diffraction (XRD) analysis. The presence of phases TiO2, (Al,Ti)2O3, CuAlO2, Cu3(Ti,Al)3O, Cu2(Ti,Al)4O and intermetallics of Cu-Ti were observed in the brazed joint near alumina interface; presence of Cu3Ti, Ag-Cu hypo- and hypereutectic solid solutions and formation of FeTi and TiFe2 intermetallics were observed in the brazed joint near En24 interface. The thickness of the reaction layers increased with increase in brazing time. Lap shear strength of the brazed joints increased from 56±16 MPa to 76±14 MPa with increase in brazing time from 15 minutes to 45 minutes.Keywords
Dissimilar Metal Brazing, Vacuum Brazing, Active Metal Brazing, En24 and Al2O3.
- Vacuum Brazing of Inconel 718 to Ti-6Al-4V
Authors
1 Centre for Advanced Systems, DRDO, Yadgarpalli (V), Keesar (M), Hyderabad – 501301, Telangana, IN
Source
Indian Welding Journal, Vol 50, No 4 (2017), Pagination: 47-55Abstract
The classic alloy Ti-6Al-4V is used in compression section of the turbine engine such as blades, discs and wheels. The turbine discs are amongst the most critical of components in the aeroengine and Inconel 718 is most widely used candidate alloy for these parts because of its excellent corrosion resistance, oxidation resistance, good tensile and creep properties at elevated temperatures. Fusion welding, as well as solid state welding processes of these dissimilar material combinations, result in formation of brittle intermetallic phases Ti2 Ni, TiNi3 and TiNi. The precipitation of undesirable phases such as intermetallic compounds and carbides causes a drastic deterioration in performance of the joints.
Vacuum brazing is one of the most promising routes to join dissimilar metallurgically incompatible materials. The mere fact is that brazing does not involve any substantial melting of the base materials, offers several advantages over other welding processes. The present work is an effort to understand the brazing aspects of Inconel 718 and Ti-6Al-4V, brazed at 950ºC in a high temperature vacuum furnace using Ti15Cu15Ni (wt%) brazing filler.
Vacuum brazing was successfully performed between Inconel 718 and Ti-6Al-4V. The microstructure and phases present in the bonded joints were analyzed by means of Optical Metallography, Scanning Electron Microscope, Energy Dispersive Spectrometer analysis and Electron Micro Probe Analysis. Tensile lap-shear strength of brazed joints were evaluated in the as-brazed condition. A maximum of 84 MPa and a minimum of 47 MPa strength was achieved in the brazed joints.
Keywords
Ti-6al-4v, Inconel 718, Vacuum Brazing, TiCuNi, Dissimilar Joint.References
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