Titanium alloy honeycomb vacuum brazing solution

The brazing schemes for titanium alloy and titanium alloy, titanium alloy and stainless steel honeycomb structures are as follows:
I. Vacuum brazing scheme for titanium alloy and titanium alloy honeycomb structure
1. Brazing material selection
Recommended brazing material: titanium-based brazing material (such as titanium-based amorphous foil, with a composition of Ti-37.5Zr-15Cu-10Ni). Features: Melting point range: 830–840°C; vacuum brazing temperature is usually set to 900-920°C (needs to be higher than the β phase transition temperature of the parent material, but avoids microstructure coarsening).High temperature resistance, corrosion resistance, joint strength close to the parent material, suitable for load-bearing parts.
2. Vacuum brazing process parameters
Vacuum brazing temperature: 900-920°C
Insulation time: long time (adjusted according to the height of the honeycomb core to ensure sufficient diffusion)
Brazing material thickness: 30–80 μm to meet the interface welding rate (the strength is best at 80 μm).
Vacuum degree: <4×10⁻³ Pa, avoid oxidation.
3. Joint performance
Pull-off strength: After optimization, it can reach 19.82 MPa (fracture occurs in the honeycomb core, indicating good interface bonding).
Microstructure: α+β Widmanstatten structure is formed in the brazing seam area, and a small amount of intermetallic compounds (such as Ti-Cu, Ti-Fe) have little effect on strength.
II. Vacuum brazing scheme for titanium alloy and stainless steel honeycomb structure
1. Brazing material selection
Recommended brazing material: Ag-based brazing material (recommended).
Ti-based brazing materials (such as Ti-Zr-Cu-Ni) have poor wettability with stainless steel, brittle intermetallic compounds (such as Ti-Fe, Ti-Cu) are generated at the interface, and the microhardness is too high (400–460 HV), resulting in low interface bonding strength.Ag-based brazing materials have good wettability and more controllable interface reactions.
2. Process parameters
Vacuum brazing temperature: 810-830°C
Hot holding time: 10 minutes
Brazing filler layer: Ensure sufficient wetting to avoid residual brittle phase (such as Ti-Fe).
3. Joint performance
Tensile strength: up to 10.35 MPa (destruction occurs in the honeycomb core, indicating reliable interface bonding).
Microstructure: The interfaces are 304 stainless steel/Ti-Fe intermetallic compound/Ag-Cu compound/TC4 titanium alloy.The microhardness of the brazing seam area is 103–111 HV, which is significantly lower than that of Ti-based brazing filler (400+ HV).
III. Key process differences and precautions
Interface reaction control:
When vacuum brazing titanium alloy and stainless steel, brittle intermetallic compounds (such as Ti-Fe, Ti-Cu) need to be suppressed, and Ag-based brazing filler is preferred.Ti-based brazing filler needs to strictly limit the brazing temperature and time to avoid residual brittle phase in the non-diffusion zone.
Welding rate and plugging rate:
When vacuum brazing titanium alloy honeycomb, the amount of brazing filler metal added directly affects the plugging rate of the muffler hole. The recommended brazing filler metal thickness is 30 μm, taking into account both the welding rate and acoustic performance (plugging rate <5%).
Performance optimization direction:
Brazing between titanium alloys improves the uniformity of the α+β structure in the weld zone by adjusting the diffusion time; brazing of heterogeneous materials requires an intermediate layer (such as Cu/Ni) or a composite brazing filler metal to reduce the interface brittleness.
IV. Recommendations for vacuum brazing scheme
Conclusion of vacuum brazing scheme Based on the comparative data of the brazing process of two types of titanium alloy honeycombs, high-strength titanium-based brazing filler metal (900-920°C/long time) is preferred between titanium alloys, and Ag-based brazing filler metal (810-830°C/10min) is recommended for heterogeneous materials. Both need to control the brazing filler metal thickness and process parameters to ensure welding rate and mechanical properties.

Vacuum Brazing Furnace

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