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Diffusion welding method for stainless steel and Kovar alloy dissimilar metal

A dissimilar metal and stainless steel technology, which is applied in the field of special material connection, can solve the problems of poor welding performance of stainless steel and Kovar alloy, achieve excellent chemical and physical properties, high weld density, and improve tensile performance Effect

Active Publication Date: 2017-01-04
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to overcome the shortcomings of the poor welding performance of stainless steel and Kovar alloy in the prior art, and provide a method for diffusion welding of stainless steel and Kovar alloy dissimilar metals

Method used

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  • Diffusion welding method for stainless steel and Kovar alloy dissimilar metal
  • Diffusion welding method for stainless steel and Kovar alloy dissimilar metal
  • Diffusion welding method for stainless steel and Kovar alloy dissimilar metal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Grind the surface to be welded of 316L stainless steel and 4J29 Kovar alloy to make the roughness Ra≤2.0μm, put the polished sample and 80μm nickel foil into acetone for 10min ultrasonic cleaning, wipe the surface to be welded with alcohol, and dry it , to obtain cleaned stainless steel, Kovar alloy and nickel foil. Press cleaned stainless steel, Kovar and nickel foils figure 1 stack, use figure 1 The vacuum heat press mechanism shown in . During the pressing process, it is necessary to maintain a good axial neutrality between the sample and the indenter, apply a pre-pressure of 18MPa to the sample to be welded through the upper indenter, and release the pressure; the vacuum hot-press furnace is evacuated to 3×10 -1 Pa; heat up the vacuum hot-press furnace at a rate of 10°C / min. After raising the furnace temperature to 850°C, pressurize to 34.66MPa, hold the heat for 2 hours for diffusion welding; after the heat preservation is over, release the pressure and cool slow...

Embodiment 2

[0034] Grind the surface of 316L stainless steel and 4J29 Kovar alloy to be welded to make the roughness Ra≤2.0μm, put the polished sample and 70μm nickel foil into acetone for 15min ultrasonic cleaning, wipe the surface to be welded with alcohol, and blow it with cold wind Dry to obtain cleaned stainless steel, Kovar and nickel foils. Press cleaned stainless steel, Kovar and nickel foils figure 1 Stacking (nickel foil sandwiched between the two), it is necessary to maintain good axial neutrality between the sample and the indenter, apply a pre-pressure of 20MPa to the sample to be welded through the upper indenter, and release the pressure; Vacuum to 2~5×10 -1 Pa; heat up the vacuum hot-press furnace at a rate of 10°C / min. After raising the furnace temperature to 900°C, pressurize to 34.66MPa, keep the heat for 3 hours for diffusion welding; after the heat preservation is over, release the pressure and cool slowly , the slow cooling rate is 5°C / min, and the slow cooling end...

Embodiment 3

[0052] The same process as in Example 2 is used to weld stainless steel and Kovar alloy. The difference is that a plurality of nickel foils with different thicknesses are used. For the effect of diffusion welding between stainless steel and Kovar, the results are as follows.

[0053] Table 3 Mechanical Properties of Stainless Steel / Kovar Alloy Welded Parts

[0054] sample Tensile strength (MPa) Elongation(%) Fracture location Example 2 (70μm) 501.84 38.75 4J29 Example 3 (40μm) 371.01 12.36 welding interface Example 3 (80μm) 485.54 37.44 4J29 Example 3 (100μm) 450.68 26.25 Interface / 4J29 Example 3 (130μm) 251.27 13.37 welding interface

[0055] From the situation recorded in Table 3, it can be seen that when the welding scheme of stainless steel and Kovar alloy of the present invention is used for welding connection, the thickness selection of nickel foil has a great influence on the mechanical properties of the wel...

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Abstract

The invention discloses a diffusion welding method for stainless steel and Kovar alloy dissimilar metal and belongs to the field of dissimilar metal welding. The diffusion welding method comprises the following specific steps: (1) sample surface cleaning: grinding a surface to be welded and performing ultrasonic cleaning on acetone; after the completion of cleaning, wiping the surface to be welded with alcohol and blow-drying or airing to obtain cleaned stainless steel, Kovar alloy and a nickel foil; (2) sample stacking: alternately stacking the cleaned stainless steel, Kovar alloy and nickel foil obtained in the step (1); (3) welding: putting a stacked sample between an upper pressing head and a lower pressing head of a vacuum hot pressing furnace, maintaining the good axial centering property between the sample and the pressing heads and performing pressure relief, wherein the pre-pressure is 15-30 MPa; vacuumizing the vacuum hot pressing furnace to (2-5)*10<-1> Pa; raising the temperature at a speed of 5-20 DEG C / min, pressurizing after the temperature inside the furnace is raised to a certain temperature, preserving heat and pressure for a certain time and performing diffusion welding; after heat preservation, performing pressure relief, firstly slowly cooling and then cooling along with the furnace. A welding seam has the advantages of being high in compactness, good in plasticity, free from air hole and crack and the like.

Description

technical field [0001] The invention relates to a material welding (connecting) technology, in particular to a method for diffusion welding of stainless steel and Kovar alloy dissimilar metals, and belongs to the field of special material connection. Background technique [0002] The miniature metal Dewar device provides good electrical, mechanical, thermal and optical transmission channels for the low-temperature working environment of the infrared focal plane detector, and is the key device for the packaging and protection of the infrared focal plane detector. Stainless steel and Kovar are the main materials used in Dewar devices. However, there are many problems in the welding between Kovar alloy and stainless steel dissimilar metals used in Dewar materials. The differences in physical and chemical properties (such as expansion coefficient, specific heat capacity, thermal conductivity, melting point) of different metal materials , chemical composition, etc.) will lead to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K20/02B23K20/22B23K20/24
CPCB23K20/02B23K20/22B23K20/24B23K2103/18
Inventor 蒋小松宋庭丰张归航邵甄胰莫德锋朱德贵朱旻昊
Owner SOUTHWEST JIAOTONG UNIV
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