The Interfacial Microstructure and Mechanical Properties of Diffusion-Bonded Joints of 316L Stainless Steel and the 4J29 Kovar Alloy Using Nickel as an Interlayer

• Published in: Metals (Basel ) 2016-11, Vol.6 (11), p.263-263
• Main Authors: Song, Tingfeng, Jiang, Xiaosong, Shao, Zhenyi, Mo, Defeng, Zhu, Degui, Zhu, Minhao
• Format: Article
• Language: English
• Subjects: 316 stainless steel; 4J29 Kovar alloy; Alloy steels; Alloys; Austenitic stainless steels; Bonded joints; Bonding strength; Carbon steel; Cobalt; Diamond pyramid hardness; Diffusion barriers; Diffusion bonding; Diffusion welding; Ductile fracture; Electron probe microanalysis; Ferritic stainless steel; Ferrous alloys; Fracture surfaces; Friction welding; Grain boundaries; Heat resistant steels; High temperature; Hot pressing; Interdiffusion; Interlayers; Iron; Kovar (trademark); Lasers; Mechanical properties; Metals; Microscopy; Microstructure; Nickel; Nickel base alloys; Optical microscopy; Solid solutions; Stainless steels; Superalloys; Tensile strength
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met6110263

316L stainless steel (Fe–18Cr–11Ni) and a Kovar (Fe–29Ni–17Co or 4J29) alloy were diffusion-bonded via vacuum hot-pressing in a temperature range of 850–950 °C with an interval of 50 °C for 120 min and at 900 °C for 180 and 240 min, under a pressure of 34.66 MPa. Interfacial microstructures of diffusion-bonded joints were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). The inter-diffusion of the elements across the diffusion interface was revealed via electron probe microanalysis (EPMA). The mechanical properties of the joints were investigated via micro Vickers hardness and tensile strength. The results show that an Ni interlayer can serve as an effective diffusion barrier for the bonding of 316L stainless steel and the 4J29 Kovar alloy. The composition of the joints was 316L/Ni s.s (Fe–Cr–Ni)/remnant Ni/Ni s.s (Fe–Co–Ni)/4J29. The highest tensile strength of 504.91 MPa with an elongation of 38.75% was obtained at 900 °C for 240 min. After the width of nickel solid solution (Fe–Co–Ni) sufficiently increased, failure located at the 4J29 side and the fracture surface indicated a ductile nature.