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Stainless steel tube plate joint electron beam brazing

Elements, including 81.78% Ni, 7.52% Si and small amounts of cr, Fe, nickel and nickel silicide for the diboride phase. Black-phase high content of elements in ③ (83.35%), Ni, Si, Fe content is less, indicating that the base metal in the brazing compound to the dissolution of Cr, and solder the chemical reaction of boron compound to form a boron brittle phase of chromium. Brazing Ni, B, si spread to the base metal and base metal in the Fe, cr to dissolve solder,[link widoczny dla zalogowanych], solder and base metal interface, the full diffusion of alloying elements, resulting in nickel-boride eutectic phase and disappears,[link widoczny dla zalogowanych], forming a solid solution of nickel ④. Base metal near the weld zone of white tissue ⑤ mesh nickel-chromium boron silicon as a low-melting eutectic phase is Brazing of Ni, B, si elements of the base metal along the grain boundary diffusion of the results. ⑤ white tissue spread to the base material, from the micro perspective is through surface diffusion, grain boundary diffusion and spread of the crystal to achieve. Surface diffusion rate, followed by the grain boundary diffusion. Lattice distortion exists at the grain boundaries, atoms at a higher energy state, easy to beat and migration. Solder-component Ni, B, Si elements in the diffusion process to the capillary wall, in the grain boundary diffusion coefficient, diffusion speed is high,[link widoczny dla zalogowanych], the diffusion process and the matrix material to form eutectic phase, crystal dissolution, grain boundary becomes wider. Table 2 because the electron beam electron beam brazing the chemical composition of each phase (mass fraction,%) Table2Phasecompositionofelectronbeambrazedjoint brazing heating temperature is low, the heating time is short, the proliferation of small crystals. 4 Conclusion (1) by electron beam brazing technology can be successfully achieved by capillary plate connections, greatly improve the brazing efficiency. (2) in the optimization of electron beam brazing specification, using a 2 BNi brazing joint quality stainless steel capillary plate to meet the technical specifications, drill penetration rate of 100%, capillary no dissolution. (3) beam with the electron beam increases, the heating time prolonged, increase focus and scanning the amplitude of the current decreases, the input to the workpiece electron beam power density, height and angle solder solder spread to the depth of the capillary wall increased. (4) stainless steel capillary plate electron beam brazing process, the solder joints mainly of nickel boride phase, boride phases of nickel and nickel silicide, boride, and nickel-chromium solid solution phase composition. References: [1] YangP, TunnanBN. Brazemicrostructureevolutionandmeehan. icalpropertiesofelectronbeamjoinedceramics [J]. MaterialsChemistryandPhysics, 2000, (64) :137-146. [2] GoodmanDL, BirxDL, DaveVR. Hishenergyelectronbeamprocessingexperimentswithinductionaccelerators [J]. NuclearInstrumentsandMethodsinPhysicsResearch, 1995, B (99) :775-779. [3] JanFelba, KazimierzPFriede [, PeterKruU, eta1. E [ectronbeamactivatedbrazingofcubicboronnitridetotungstencarbidecuttingtools [J]. Vacuum, 2001, (62) :171-180. [4] Liu Fangjun, Mao Zhiyong, Chen Gang, et al. Stainless steel tube plate joints by electron beam brazing of [A]. Proceedings Ninth National Welding Conference (Volume 1) [c]. Heilongjiang: Heilongjiang People's Publishing House ,1999,561-564. [5] LI Shao-qing, ZHANG Yu-new, Feng-gui, et al. 2 BNi a solder vacuum electron beam brazing [J]. Aeronautical Manufacturing Technology, 2004, (9) 72-75. [6] Zhuang Hongshou, Roger Shuttleworth E. High temperature brazing [M]. Beijing: National Defence Industry Press, l989.25-85. [7] Zhang Qi-Yun, Zhuang Hongshou. Brazing Manual [M]. Beijing: Mechanical Industry Press, 1998.1O a 12 Author: LI Shao-qing, female,[link widoczny dla zalogowanych], born in January 1979,[link widoczny dla zalogowanych], PhD. Research interests include high-energy beam welding and composite technology, numerical analysis of welding process. Articles have been published more than lO. Email: lishaoqing @ sjtu. edu. cn

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