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Experiment Research on Low Vacuum Brazing Stainless Steel Oil Cooler with Pure Copper Solder

Author: ZhengYanSong
Tutor: QianYiYu；HePeng
School: Harbin Institute of Technology
Course: Materials Processing Engineering
Keywords: Stainless steel plate-fin oil cooler Pure copper solder Low vacuum brazing To film mechanism Copper solder evaporation Brazing seam forming
CLC: TG454
Type: Master's thesis
Year: 2011
Downloads: 50
Quote: 0
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Abstract

ISX stainless steel plate-fin oil cooler failures start by product failure analysis found that, brazing the angle and brazing process between the oil cooler fins and chip solder evaporation deposition on the fin copper layer The gear oils active sulfides contact corrosion reaction occurs, corrosion products entering the engine to produce adverse effects on the mechanical properties as well as to accumulate in the oil cooler. And address the feasibility of end-of-life product issues due to the corrosion of copper through the experimental study of chemical cleaning method, the results show that the chemical cleaning method achieved remarkable results in reducing corrosion source, but taking into account the actual production of a chemical cleaning solution stability, reduced product life, and increasing the production cost, and other issues, the program application is limited. And from the point of view of controlling corrosion source stainless steel oil cooler low copper brazing process. Improve product assembly precision by product parts production mold precision, and so on, under the solder foil thickness is reduced from 0.12mm and 0.08mm to 0.08mm and 0.06mm, so as to achieve the purpose of reducing the amount of solder, and the trial found The corrosion products of the gear oil of the oil cooler as reduce the amount of brazing material almost proportional decrease; Further, according to the structural characteristics of the brazing of the plate-fin oil cooler, through the portion contacting the brazing filler metal foil after the assembly with the fins hollow reasonable configuration of the brazing material, the way to further reduce the amount of the brazing material, so that the size of the brazing angle fins chip copper vapor deposition layer has a thickness decreased significantly, effective control of the source of high temperature corrosion of the gear oil, and a substantial amount of solder reduced, not only did not affect the quality of the brazing, but to improve the products bursting strength. Meanwhile, the related test and theoretical analysis for stainless steel plate-fin oil cooler using the pure copper solder brazing actual production characteristics under low vacuum conditions, the removal mechanism of oxide film on the surface of stainless steel and solder spreading caulk mechanism , provides a theoretical basis for the optimization of the production process. Through the experimental study and thermodynamic calculation of the stainless steel to membrane mechanism is based on stainless steel decarburization and vacuum furnace graphite rod heating elements evaporated carbon Cr ₂ O ₃ reactions caused by the oxide film metamorphosis and loosening, and during the heating process due to the surface oxide film and the stainless steel substrate by thermal expansion coefficient difference of the oxide film occurs microcracks. In the stainless steel surface occurs go film role in the process, along with the copper brazing material of the evaporator and on the stainless steel substrate occurred effective deposition, the test results showed, 1050 ° C appears copper evaporation deposition layer to the stainless steel substrate, atomic diffusion to achieve a deposited layer solid phase connected with the stainless steel. Therefore, the the brazing seam formation process with copper solder low vacuum brazing of stainless steel is actually mixed with each other with the evaporation of liquid copper deposition layer flow spreading caulk solder melting process. When the temperature is below the melting point of the brazing material, it has been the phenomenon of diffusion by the copper vapor deposition layer to the stainless steel, to play the role of pre-alloyed on the surface of the stainless steel substrate, thus effectively reducing the interfacial tension of the brazing material and the base material, and promote the brazing mixed flow of material with liquid deposition layer spreading caulk. In addition, the solder melts the caulking process in the base body of the base material under the conditions of a large number of dislocation networks exist, as well as stainless steel nickel atoms preferential diffusion driven by the role of the brazing material and the base material to a relatively strong interaction occurs, the solder forming a metallurgical bond with the parent material, and to promote the formation of high-quality brazed joints.

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