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Study on Arc Brazing of Nickel-Based Alloy and Stainless Steel

Author: SongJianLing
Tutor: LinSanBao
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: TIG braze MIG brazing Process parameters Mechanical properties Microstructure
CLC: TG454
Type: Master's thesis
Year: 2007
Downloads: 345
Quote: 2
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Abstract


Beam of a model rocket engine nozzle extension is made more than 300 nickel-base alloy made of thin-walled square tube welding in the manufacture of finished which you need to be welded stainless steel reinforcement ring constraint. Arc Brazing low heat input, can strictly control the welding distortion, thin-walled parts to avoid excessive ablation, with energy efficient features. This topic carried out nickel-based alloys and stainless steel arc brazing dissimilar materials research. The five kinds of wire on the primaries were carried out wettability test and process test, analysis of morphology and mechanical properties of the joints. The results showed that: CuSiMn solder flux best, and surface defects and more brittle joint area; CuSi3 copper solder wetting and spreading good joint surface shaping good, stable welding process; CuAl8 solder surface forming poor, easy to form an unbound joint region; CuFeMn poor solder wettability, wetting coefficient is negative, the surface forming poor, poor stability of the welding process. Final selection CuSi3 and copper wire as the two kinds of nickel-based alloy and stainless steel arc brazing wire. Using CuSi3 and copper wire were systematically TIG brazing process test, study the torch position, process parameters on the joint performance. The results show that: the use of vertical welding torch, welding torch from stainless steel edge 0.8 ~ 10mm at the droplet to form a continuous bridge network transition, good weld high joint strength; ideal range of process parameters: welding current 30 ~ 35A, arc length 3.0 ~ 4.0mm, welding speed 100 ~ 150mm/min, wire feed speed 200 ~ 300mm/min. CuSi3 joint highest intensity reached 195.0MPa, fracture surface is shallow dimple-like ductile fracture. Copper fittings plasticity than CuSi3 joints, fracture of plastic shear dimple fracture shear strength of 183.3MPa. Analysis of the TIG brazed districts microstructure, tested joint tissue components. The results showed that: the solder and Ni-based alloys and stainless steel have occurred in the interface reaction, a small amount of melted solder preform with a liquid mixture formed weld solidification. Hastelloy Cupronickel interface reaction dendrites group, the thickness of base metal melting 0.0348mm, accounting for 10.55% of the base material; stainless steel upper melt volume, with the lower part of brazing, the interface reaction layer of Fe on the distribution of the substrate The two granular α-Cu phase structure; weld zone is in α-Cu matrix on the distribution of Fe-based solid solution of spherical two-phase structure. In order to improve the welding efficiency for CMT technology based MIG brazing process preliminary study. The results show that the ideal range of process parameters: welding current 85A, the welding voltage is 12.6V, the welding speed of 0.9 ~ 1.2m/min, wire feed speed 5.0m/min; joint strength of 184.9MPa; thickness of the Ni-based alloy is melted 0.0143mm, accounting for 4.33% base metal; weld zone is α-Cu matrix and particulate Fe-based solid solution of two-phase structure.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Brazing
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