Interfacial strengthening mechanism of electron beam welding-brazed TZM/30CrMnSiA joint with a vanadium interlayer

The composite structures of TZM alloy and 30CrMnSiA steel have broad application prospects in nuclear power and aerospace industries, while the problem of the joint embrittlement has not been solved. Therefore, pure vanadium, which has excellent metallurgical compatibility with base materials is selected as the filler metal to produce high strength joints. Microstructures, mechanical properties, and TZM/FZ interfacial characteristics of the joints without V foil and with V foil were analyzed. The results indicate that: (i) there is a Fe2Mo intermetallic compound layer along with the TZM/FZ interface without V foil, which will deteriorate the mechanical properties of the joint. After adding pure V foil, there is no reactive layer appearing at the TZM/FZ interface; (ii) the joint without V foil fractured along the interface between TZM and Fe2Mo, the strength of which is only 165.2 MPa, while the tensile strength of the joint with V foil reaches 312.7 MPa; (iii) through calculating the interfacial ideal adhesion energy, it can be found that the interfacial bonding strength of the Mo (111)/V(Fe)ss (111) interface is higher than that of the Mo (111)/Fe2Mo(100) interface.