Hard Overlay with Tungsten Carbide Cords
Flexible cords with embedded tungsten carbide enable controlled application in defined composition – including on complex geometries or hard-to-reach areas.
Flame brazing, also known as torch brazing internationally, is one of the established processes for targeted surface reinforcement and repair of highly stressed components. In combination with self-fluxing matrix alloys and tungsten carbide hard overlay systems, it forms an economically attractive, technically mature process for wear, corrosion and combined loading applications.
An essential difference from classical welding processes lies in the low process temperature: the base material is not melted, only heated near the surface. The self-fluxing matrix alloy melts, wets the substrate and bonds metallurgically with it. Heat input, distortion and cracking risk remain significantly lower than with fusion welding processes.
Flame brazing becomes particularly effective in combination with flexible hard overlay systems such as tungsten carbide cords. The carbides are not melted, but specifically embedded in the liquid matrix – their hardness, shape and structure are fully preserved. The resulting composite material combines matrix toughness with the extraordinary abrasion and erosion resistance of tungsten carbide.
Flame Brazing for Hard Overlay, Wear Protection and Component Regeneration
We deploy flame brazing specifically when components need to be protected against wear, corrosion or combined loading – without melting the base material and with minimal heat input. Using self-fluxing matrix alloys on nickel, cobalt or iron basis as well as flexible hard overlay cords with tungsten carbide, layers can be applied precisely where they are needed in operation.
Wear Protection on Conveying and Mixing Systems
Targeted layers on screws, mixing arms, seating surfaces and other wear-stressed components – economical alternative to component replacement.
Repair and Regeneration of Worn Components
Local reworking or restoration of worn functional surfaces – without complete component replacement, with reduced downtime and lower material usage.
Self-Fluxing Matrix Alloys
Matrix on nickel, cobalt or iron basis with flux-forming constituents – uniform melting, self-flowing behaviour and low-porosity layers with defined geometry.
Layers without Melting the Base Material
The base material is only heated near the surface – heat input, distortion and microstructural changes are minimised. Ideal for sensitive or highly stressed components.
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We support you in selecting the right welding process and the appropriate solution.
Advantages of Flame Brazing in Industrial Use
Flame brazing combines low heat input with high adhesion strength and excellent wear protection. Since the base material is not melted, its microstructure remains largely unchanged – distortion, cracks and material damage are minimised.
The flexible application via hard overlay cords and the controlled adjustability via matrix selection, carbide size and carbide content make the process a powerful choice for repair, regeneration and targeted wear protection on highly stressed components.
Low Process Temperature without Melting the Base Material
Base materials are only heated near the surface. Heat input, distortion and the risk of cracks or microstructural changes are considerably reduced.
Carbide Retention for Maximum Wear Protection
Tungsten carbides are not melted but embedded undestroyed in the liquid matrix. The hardness, shape and structure of the carbides are fully preserved.
Self-Fluxing Matrix with Uniform Layer Formation
Matrix alloys on Ni, Co or Fe basis contain flux-forming constituents. The layer flows out on its own, is low in porosity, dense and smooth.
Flexible Application via Hard Overlay Cord
Cords with defined matrix and carbide content enable controlled application even on complex geometries or hard-to-reach areas. The wear layer sits exactly where it is needed.
Economical Repair Instead of Component Replacement
Worn components can be regenerated in a targeted manner – downtime, material usage and total costs are significantly reduced compared to component replacement.
Adjustable Layer Properties per Application
By selecting matrix, carbide size, carbide shape and carbide content, the wear protection is precisely adapted to the loading – from abrasion and erosion to corrosion stress.
When Is Flame Brazing the Right Choice?
Flame brazing is the right choice whenever a hard overlay with high wear resistance needs to be applied without melting the base material. Also where distortion, microstructural changes or cracking risk caused by melting must be avoided, the process demonstrates its strengths.
Typical application fields are conveying and mixing systems, pumps and valves, valve seating surfaces, mixers and many other wear-stressed components – both in new construction and in repair and regeneration.
Flame brazing is particularly suitable for applications where:
tungsten carbide hard overlays with fully preserved carbide structure are required.
the base material must be thermally protected, for example due to cracking risk, microstructural sensitivity or tendency to distort.
complex geometries or hard-to-reach areas need to be coated flexibly.
worn components are to be regenerated rather than replaced, in order to reduce downtime and material costs.
wear, erosion, corrosion or combined loading must be reliably addressed.
Flame Brazing Compared to Other Welding Processes
Classification and Characteristics of Flame Brazing
Flame brazing, Torch Brazing internationally, is positioned between classical fusion welding processes and thermal spraying processes. Characteristic is the low process temperature – the base material is not melted, only heated near the surface. The self-fluxing matrix alloy melts, wets the substrate and forms a genuine metallurgical bond.
This significantly reduces heat input and distortion, and the risk of cracks or microstructural changes in the base material remains low. Carbides are fully preserved and embedded undestroyed in the matrix – a central advantage over arc-based overlay processes.
Through the choice of matrix alloy, carbide system and cord geometry, layer properties can be precisely adapted to the loading. The process is suitable for both new parts and for repair and regeneration of worn components.
Differences to Hard Brazing, TIG Brazing and Oxyacetylene Welding
Hard Brazing (inductive / in furnace)
Hard brazing with inductive or furnace heating is the industrial, automatable alternative for series production. The uniform heating ensures particularly reproducible layers and tight tolerances, but requires component-specific inductors or matching furnace geometries. Flame brazing retains the advantage for individual parts, large or hard-to-transport components, and for flexible application directly at the point of use.
TIG Brazing (shielding gas brazing)
TIG brazing uses an electric arc with a non-consumable tungsten electrode as energy source – finer heat input, less distortion and particularly relevant for thin sheet or galvanised materials. Flame brazing scores when no power supply is available, larger component sections need to be heated uniformly, or tungsten carbide hard overlays are to be applied by cord.
Oxyacetylene Welding
Oxyacetylene welding uses the same gas flame equipment as flame brazing, but melts the base material and produces a fusion bond. Flame brazing works without melting the base material – the matrix only wets the surface and bonds metallurgically. That is the central decision between brazing and welding: thermal protection and carbide retention argue for flame brazing; a full fusion bond with classical weld appearance for oxyacetylene welding.
Precise Technology. Clear Process. How We Work.
Every cladding project follows a structured workflow – from the initial component analysis to the inspected deposit layer. This produces reproducible results tailored to loading conditions, material and operating environment.
1. Component Analysis
In the first step, the geometry, material and operating conditions of the component are recorded. This includes the type of loading – such as wear, corrosion or thermal stress – as well as the required layer properties. On this basis, the appropriate welding process is selected and the process is designed.
2. Selection of Welding Consumable
Depending on requirements, different welding consumables and alloys are used, for example for wear protection, corrosion protection or heat resistance. The material selection is matched to the base material and the subsequent loading to achieve a permanently stable bond.
3. Component Preparation
Before cladding, the component is prepared accordingly. This includes cleaning the surface, removing contamination and, if necessary, mechanical preparation of the coating area. A clean surface is the foundation for a metallurgical bond and reproducible layer quality.
4. Cladding
Cladding is carried out with precisely set process parameters. Energy input, material feed and welding speed are controlled specifically to set layer thickness and penetration behaviour in a controlled manner. This produces homogeneous deposit layers with defined properties.
5. Quality Inspection
After cladding, the layer is mechanically post-processed as required, for example by turning or grinding, to achieve the required dimensional accuracy. Finally, the quality inspection of the weld seam and deposit layer is carried out before the component is returned to the customer.
Andreas Frische
Technical Management
Finding the Right Welding Process
Not sure which welding process is right for your application?
We support you in selecting and combining the right processes.
+49 5202 97790-54
Available from 07:45 - 16:30
a.frische@capilla-gmbh.de
Available from 07:45 - 16:30
Without the right welding consumable, there is no stable solution.
In flame brazing, the matrix alloy, carbide system and cord construction determine the wear resistance, hardness and bonding quality of the hard overlay layer – from thin protective layers to massive overlay areas.
capilla supplies hard overlay cords and self-fluxing matrix alloys on nickel, cobalt and iron basis, with tungsten carbide and further hard material systems – individually matched to loading, component and service life requirement.
Automated Welding Processes at the capilla LCC
At the Laser Competence Centre (LCC), capilla brings together modern technologies for automated coating and manufacturing. Components are precisely built up, heat-treated and tailored to the application using laser-based processes. Layer thickness, material deposition and process parameters can be precisely controlled – even for complex geometries and series applications.
This produces coating and manufacturing solutions that go beyond conventional welding processes and cannot be realised with traditional approaches in this form.
Frequently Asked Questions about Flame Brazing
Flame brazing, also known as torch brazing internationally, is a thermal joining process in which the base material is not melted. An oxyacetylene flame heats the component near the surface and melts the self-fluxing matrix alloy, which wets the substrate and bonds metallurgically with it.
In industrial wear protection, flame brazing is particularly often used as flame hard brazing in combination with tungsten carbide hard overlay systems. The carbides remain undestroyed and are specifically embedded in the matrix – ideal for repair, regeneration and targeted wear protection on highly stressed components.
capilla deploys flame brazing for hard overlays with tungsten carbide, targeted wear protection layers and economical component regeneration.
In flame brazing with self-fluxing matrix alloys, the component is first uniformly preheated to avoid thermal stresses. The cord or filler material is then melted with the oxyacetylene flame. The matrix flows out on its own, wets the substrate and surrounds embedded carbides uniformly.
The matrix is frequently based on nickel, cobalt or iron and contains flux-forming constituents that allow the uniform melting and flowing of the alloy. After cooling, a low-porosity, dense and smooth hard overlay layer is formed with high adhesion strength and metallurgical bonding to the base material.
capilla supplies self-fluxing matrix alloys matched to carbide system, loading and base material.
Flame brazing is industrially used wherever wear-stressed components need to be equipped with high wear resistance without thermally stressing the base material. Typical applications are screws, mixing arms, conveying systems, valves, seating surfaces, mixers and other components in processing, conveying and process technology.
Flame brazing also plays a central role in repair and regeneration: worn components can be reworked in a targeted manner without having to replace the entire component. This reduces downtime, saves material and significantly lowers total costs – both for new parts and in ongoing plant operation.
capilla advises on application and supplies the appropriate hard overlay systems for every type of loading.
The central advantage over classical welding processes is the significantly lower process temperature. Since the base material is not melted, its microstructure and mechanical properties remain largely unchanged. Heat input, distortion and the risk of cracks or microstructural changes are considerably reduced.
Added to this is complete carbide retention: tungsten carbides are not melted but embedded undestroyed in the liquid matrix. The resulting composite material combines matrix toughness with the extraordinary abrasion and erosion resistance of tungsten carbide – a property that arc-based welding processes do not achieve to the same extent with the same carbide selection.
capilla deploys flame brazing specifically when the base material must be thermally protected and carbides fully preserved.
Flame brazing processes a broad spectrum of base materials – including unalloyed and low-alloy structural steels, high-strength steels, stainless steels, cast iron and selected non-ferrous metals. The prerequisite is sufficient metallurgical compatibility with the chosen matrix alloy and a clean surface prepared free of contamination.
The process is particularly in demand for materials that are susceptible to cracking or distortion with classical fusion welding processes. The low process temperature and the absence of base material melting open up applications that would not be technically or economically sensible with arc or laser processes.
capilla advises on material suitability and matches matrix and hard overlay system to the base material.
In flame brazing, self-fluxing matrix alloys are used, frequently on nickel, cobalt or iron basis. Nickel-based matrices deliver a good combination of toughness, corrosion resistance and processability – they are a typical standard for wear protection with tungsten carbide. Cobalt-based matrices score at high-temperature and combined loading applications.
Iron-based matrices are mainly used in economically oriented applications with high wear loading and moderate corrosion requirements. The matrix contains flux-forming constituents in each case, ensuring uniform melting and self-flowing behaviour.
capilla selects the matrix system and carbide content precisely according to loading, component and service life requirement.
Hard brazing with tungsten carbide is suitable wherever extreme abrasion and erosion resistance is required but the base material must not be thermally overloaded. Typical applications are mixing arms, screw blades, conveying systems, seating surfaces and other components with high abrasive wear fraction – also in combination with corrosion or impact loading.
The embedded tungsten carbides retain their extraordinary hardness since they are not melted. The matrix provides toughness, adhesion and corrosion protection. By varying carbide size, carbide content and matrix selection, the wear protection can be precisely adapted to the respective loading – from fine layers on sensitive components to robust overlay areas on solid parts.
capilla stocks tungsten carbide hard overlay systems in various carbide sizes, carbide contents and matrix systems.
Compared to other hard brazing processes such as induction brazing or furnace brazing, flame brazing is characterised by high flexibility, low equipment investment and mobile deployability. The oxyacetylene flame allows the processing of large, complex or hard-to-transport components directly on site – without elaborate fixtures or special plant technology.
Induction brazing is by comparison better automatable and more reproducible for series parts, but requires component-specific inductors and stationary equipment. Furnace brazing offers the highest reproducibility but is limited to component sizes that fit in the furnace. Flame brazing fills the gap for individual, mobile and large-component applications.
capilla deploys flame brazing when flexibility, component size or mobile application argue against stationary brazing processes.
Hard brazing cords contain matrix alloy and embedded tungsten carbides already in defined composition. This allows a very controlled and uniform application – even on complex geometries or hard-to-reach areas. The flexible design allows exact positioning of the wear layer precisely where it is needed in operation.
In the process, the component is first preheated, then the cord is melted with the oxyacetylene flame. The matrix flows out on its own, wets the substrate and surrounds the carbides. Through selection of cord construction, carbide size, carbide shape and carbide content, layer properties can be specifically set.
capilla stocks hard brazing cords in various geometries, carbide systems and matrix variants.
Yes, flame brazing is particularly well suited for repair and regeneration of worn components. Since the base material is not melted, the component remains thermally almost unloaded – a decisive advantage for large, complex or high-quality components that are not to be replaced.
Typical repairs are filling of worn functional surfaces, restoration of seating surfaces and mixing blades, local reinforcement of stressed areas and protection against further wear. Downtime, material usage and total costs are significantly reduced compared to component replacement.
capilla supports economical repair and regeneration of worn components with tungsten carbide hard overlays.