Pulse Pressuring Diffusion Bonding of Ti Alloy/Austenite Stainless Steel Processed by Surface Self-nanocrystallization

Abstract

Nanostructured surface layers were synthesized on the end face of Ti-4Al-2V titanium alloy and 0Cr18Ni9Ti austenite stainless steel rods by means of high energy shot peening (HESP). Making treated end surfaces as bonding interfaces, Ti-4Al-2V and 0Cr18Ni9Ti rods were bonded by pulse pressuring diffusion bonding (PPDB) on Gleeble-1500D tester at 650-750°C. Joints were tested on tensile testing machine, the fractures and microstructures of joints were researched. Results showed that the maximum tension strength of 262.0 MPa was achieved, cleavage fracture took place while tension test of joints, and the grains in the vicinity of the diffusion layer are fined. But, brittle intermetallic compounds were absence on the bonding interface.KEY WORDS: titanium alloy; stainless steel; pulse pressuring diffusion bonding (PPDB); intermetallic compound.

Pulse Pressuring Diffusion Bonding of Ti–4Al–2V/0Cr18Ni9Ti with Nanostructured Layer Synthesized by Surface Self-nanocrystallization

“…However, intermetallic compounds of Fe, Ti, Cr can not be yielded during diffusion bonding of Ti-4Al-2V and 0Cr18Ni9Ti under 850°C. 13) Ghosh et al inferred that diffusion bonded joints of titanium to stainless steel contains s phase, c phase, Fe 2 Ti, FeTi and Cr 2 Ti intermetallic compounds in the diffusion zone when processed at 850°C. 19) …”

“…13) Nanomicrostructures prepared by the SSNC include a large volume fraction of stored energy and non-equilibrium defective resulting in refining of coarse grains such as dislocations, vacancy, subboundary, which may promote chemical reaction of different atoms and enhance atomic diffusion coefficient. 7,8) …”

“…Ti-4Al-2V alloy and 0Cr18Ni9Ti stainless steel rods with nanostructured layer on the bonding interface were bonded by constant temperature and pressure diffusion bonding (CTPDB), 12) research results showed that applying SSNC into CTPDB of Ti-4Al-2V alloy and 0Cr18Ni9Ti stainless steel bars can increase of atomic diffusion coefficient, suppresse of intermetallic compound growth, and advance tensile strength of joints. It was reported that Ti-4Al-2V and 0Cr18Ni9Ti rods with nanostructured layer on the bonding interface was bonded by pulse pressuring diffusion bonding (PPDB) under 800°C, 13) result showed that joints of titanium alloy and stainless steel was obtained under 800°C for the first time, and intermetallic compounds was not yielded on in-terface of joints, but the maximum tensile strength of joint was only 262.0 MPa. Therefor, the tensile strength of Ti-4Al-2V and 0Cr18Ni9Ti joint demand be advanced by adjusting diffusion bonding technology.…”

Reduction of Diffusion Bonding Temperature with Recrystallization at Austenitic Stainless Steel

“…Moreover, for titanium alloys, Han et al 8) regarded the mechanism as an increase in the grain boundary diffusion, which leads to fine grains due to localized severe plastic deformation and recrystallization. Almost all of our results in our current study can be potentially explained by the study of Han et al However, one of our results that needs another explanation is that the fracture load for WC/SOL, in which a material has very coarse grain size, is higher than WC/WCA or WC/WC at comparatively low bonding temperature.…”

Strain-Induced Diffusion of Nickel in Nanocrystalline Fe Produced by High Energy Shot Peening

“…Due to a high activation of atoms in nanocrystalline materials, when the atoms exchanged from two different materials into each other, metallic compounds always formed on the interface, which on some extend would prevent the further diffusion of atoms [8][9][10] . A pulse pressure exerted on the xenogenic metallic materials has been proved to be an effective way to delete the metallic compound formed during the diffusion [11] . In the present work, the iron-nickel diffusion couples were subjected to a pulse pressure to enhance the diffusivity of nickel atoms in iron, and we defined the diffusion as strain-induced diffusion.…”