What Is AWS A5.8 / A5.8M and What Does It Cover?
AWS A5.8/A5.8M is the American Welding Society specification titled "Specification for Filler Metals for Brazing and Braze Welding."
It prescribes the requirements for classification of brazing filler metals based on chemical composition, physical form, and packaging, covering more than 120 brazing filler metals.[reference:0]
The specification is also adopted as ASME SFA-5.8 and appears in Section II, Part C of the ASME Boiler and Pressure Vessel Code.
The current edition is AWS A5.8M/A5.8:2026, the 12th edition, which revises the 2019 edition.[reference:1]
The brazing filler metal groups described include aluminum, cobalt, copper, gold, magnesium, nickel, palladium, silver, titanium, and brazing filler metals for vacuum service.[reference:2]
Information is provided concerning the liquidus, the solidus, the brazing temperature range, and general areas of application recommended for each brazing filler metal.[reference:3]
Brazing filler metals have melting points lower than those of the base metals being joined and flow into closely fitted surfaces by capillary action.[reference:4]
Always verify specific classification requirements with the latest edition of A5.8/A5.8M.
What is the scope of AWS A5.8/A5.8M?
AWS A5.8/A5.8M covers brazing filler metals for brazing and braze welding processes.
The specification applies to filler metals used for joining metals and other materials without extensive fusion of the substrates.
The classification system is based on the chemical composition of the filler metal, with additional requirements for physical form, sizes, lengths, and packaging.
The specification makes use of both the International System of Units and U.S. Customary Units, with each to be used independently of the other.[reference:5]
A guide is appended to the specification as a source of information concerning the classification system employed and the intended use of the brazing filler metals.[reference:6]
AWS A5.8 brazing filler metals are classified using an alphanumeric system that begins with the letter "B" for brazing.
The prefix is followed by the chemical symbol of the principal alloying element, such as "Ag" for silver, "Cu" for copper, "Al" for aluminum, "Ni" for nickel, "Au" for gold, "Mg" for magnesium, "Co" for cobalt, or "Pd" for palladium.
A number then identifies the specific composition within that alloy family, such as BAg-1, BAg-8, BCuP-5, BNi-2, or BAu-4.
The prefix "BV" denotes vacuum-grade filler metals, such as BVAg-0 and BVAu-3, which are specially processed for vacuum brazing applications.
The designation "R" preceding certain classifications, such as RBCuZn-A through RBCuZn-D, indicates that the filler metal is used for braze welding rather than brazing.
The classification system allows users to quickly identify the alloy family and select a filler metal appropriate for the base metal and service conditions.
What is the difference between brazing and braze welding?
Brazing is a joining process in which a filler metal is heated above its melting point and distributed between two or more close-fitting parts by capillary action, with the base metal not melted.
Braze welding, by contrast, is a process in which the filler metal is deposited in a groove or fillet, similar to fusion welding, but without capillary action and without melting the base metal.
The RBCuZn series classifications in AWS A5.8 are specifically designed for braze welding applications, while most other classifications, such as the BAg, BCuP, and BNi series, are used for brazing by capillary action.
Braze welding typically produces a bead or fillet similar to a fusion weld, while brazing produces a thin, continuous joint at the interface between closely fitted parts.
What Is the Complete List of AWS A5.8 / A5.8M Types?
The AWS A5.8/A5.8M classification list comprises more than 120 brazing filler metals organized into ten major alloy groups: aluminum-silicon (BAISi), cobalt (BCo), copper (BCu), copper-phosphorus (BCuP), copper-zinc (RBCuZn), gold (BAu), magnesium (BMg), nickel (BNi), palladium (BPd), and silver (BAg).
The BAISi series includes BAISi-2, BAISi-3, BAISi-4, BAISi-5, BAISi-6, and BAISi-8, along with a general (G) classification.
The BAg series includes BAg-1, BAg-1a, BAg-2, BAg-2a, BAg-3, BAg-4, BAg-5, BAg-6, BAg-7, BAg-8, BAg-8a, BAg-9, BAg-10, BAg-11, BAg-12, BAg-13, BAg-13a, BAg-18, BAg-19, BAg-20, BAg-21, BAg-22, BAg-23, BAg-24, BAg-26, BAg-27, BAg-28, BAg-33, BAg-34, BAg-35, BAg-36, and BAg-37, along with general (G) classifications and vacuum-grade equivalents (BVAg series).
The BCuP series includes BCuP-1, BCuP-2, BCuP-3, BCuP-4, BCuP-5, BCuP-6, BCuP-7, BCuP-8, and BCuP-9.
The BNi series includes BNi-1, BNi-1a, BNi-2, BNi-3, BNi-4, BNi-5, BNi-5a, BNi-5b, BNi-6, BNi-7, BNi-8, BNi-9, BNi-10, BNi-11, BNi-12, and BNi-13.
The RBCuZn series includes RBCuZn-A, RBCuZn-B, RBCuZn-C, and RBCuZn-D.
The BAu series includes BAu-1, BAu-2, BAu-3, BAu-4, BAu-5, and BAu-6.
The BCu series includes BCu-1, BCu-1a, BCu-1b, BCu-2, BCu-3, and BCu-4.
The BCo series includes BCo-1 and additional cobalt-based classifications.
The BMg series includes BMg-1 and BMg-2.
The BPd series includes palladium-based classifications for specialized high-temperature applications.
For the complete and authoritative list of all 120+ classifications, always verify with the latest edition of A5.8/A5.8M.
Which aluminum-silicon (BAISi) classifications are included?
The aluminum-silicon classifications in AWS A5.8 are BAISi-2, BAISi-3, BAISi-4, BAISi-5, BAISi-6, and BAISi-8, along with general (G) classifications.
BAISi-2 contains approximately 92.5% aluminum and 7.5% silicon, with a brazing range of 1110°F to 1150°F, used for joining aluminum alloys 1060, 1100, 3003, 3004, 5005, 5050, 6053, 6061, 6062, 6063, and 6951.
BAISi-3 contains approximately 86% aluminum, 10% silicon, and 4% copper, suitable for torch brazing.
BAISi-4 contains approximately 88% aluminum and 12% silicon, with a brazing range of 1080°F to 1120°F, and is a common general-purpose aluminum brazing filler metal.
BAISi-5 contains approximately 90% aluminum and 10% silicon, suitable for furnace and dip brazing.
BAISi-6 contains approximately 90% aluminum, 7.5% silicon, and 2.5% magnesium.
BAISi-8 is a general-purpose aluminum brazing filler metal used for brazing aluminum and aluminum alloys.
All of these filler metals are suitable for furnace and dip brazing, with BAISi-3, -4, and -5 also suitable for torch brazing.[reference:7]
Joint clearances for aluminum brazing typically run from 0.006 to 0.025 inch.[reference:8]
Which silver (BAg) classifications are included?
The silver-based classifications in AWS A5.8 include BAg-1, BAg-1a, BAg-2, BAg-2a, BAg-3, BAg-4, BAg-5, BAg-6, BAg-7, BAg-8, BAg-8a, BAg-9, BAg-10, BAg-11, BAg-12, BAg-13, BAg-13a, BAg-18, BAg-19, BAg-20, BAg-21, BAg-22, BAg-23, BAg-24, BAg-26, BAg-27, BAg-28, BAg-33, BAg-34, BAg-35, BAg-36, and BAg-37, along with general (G) classifications and vacuum-grade equivalents designated with the "BV" prefix.
The silver content ranges from approximately 2% in the lowest-silver classifications to 99.95% in BVAg-0.
BAg-1 contains 45% silver, 15% copper, 16% zinc, and 24% cadmium, with a brazing temperature range of 1145°F to 1400°F, and is used for torch and induction brazing.
BAg-2 contains 35% silver, 26% copper, 21% zinc, and 18% cadmium, with a brazing temperature range of 1295°F to 1550°F.
BAg-3 contains 50% silver, 15.5% copper, 15.5% zinc, 16% cadmium, and 3% nickel, with a brazing range of 1270°F to 1500°F.
BAg-4 contains 40% silver, 30% copper, 28% zinc, and 2% nickel, with a brazing range of 1435°F to 1650°F.
BAg-5 contains 45% silver, 30% copper, and 25% zinc, with a brazing range of 1370°F to 1550°F, and is suitable for furnace brazing.
BAg-6 contains 50% silver, 34% copper, and 16% zinc, with a brazing range of 1425°F to 1600°F.
BAg-7 contains 56% silver, 22% copper, 17% zinc, and 5% tin, with a brazing range of 1205°F to 1400°F, and is a cadmium-free alternative widely used for food and beverage equipment.
BAg-8 contains 72% silver and 28% copper, with a brazing range of 1435°F to 1650°F, and is a eutectic alloy widely used for vacuum brazing and electronic applications.[reference:9][reference:10]
BAg-8a is a variation of BAg-8 with a small lithium addition of approximately 0.4%.[reference:11]
Many of the BAg classifications have corresponding vacuum-grade (BVAg) versions with tighter chemistry control for vacuum brazing applications.
Which copper-phosphorus (BCuP) classifications are included?
The copper-phosphorus classifications in AWS A5.8 are BCuP-1, BCuP-2, BCuP-3, BCuP-4, BCuP-5, BCuP-6, BCuP-7, BCuP-8, and BCuP-9.
BCuP-2 contains approximately 7.0% to 7.5% phosphorus with the balance copper, with a brazing temperature range of approximately 710°C to 820°C, and is used for copper-to-copper joints in plumbing, air conditioning, and refrigeration systems.[reference:12][reference:13]
BCuP-3 contains approximately 5% silver and 6% phosphorus, with a melting range of approximately 645°C to 815°C.
BCuP-5 contains approximately 15% silver and 5% phosphorus, with a melting range of approximately 645°C to 800°C, and is used for higher-strength copper-to-copper and copper-to-brass joints.
BCuP-6 contains approximately 2% silver and 6.2% phosphorus, with a melting range of approximately 645°C to 825°C.[reference:14]
BCuP-7 contains approximately 5% silver and 6% phosphorus and is used for applications requiring better flow characteristics.
BCuP-8 and BCuP-9 contain varying silver and phosphorus levels for specific application requirements.
Copper-phosphorus filler metals are self-fluxing on copper and do not require flux when brazing copper-to-copper joints, but they require flux when brazing copper to brass or bronze.
Which nickel (BNi) classifications are included?
The nickel-based classifications in AWS A5.8 include BNi-1, BNi-1a, BNi-2, BNi-3, BNi-4, BNi-5, BNi-5a, BNi-5b, BNi-6, BNi-7, BNi-8, BNi-9, BNi-10, BNi-11, BNi-12, and BNi-13.
BNi-1 contains approximately 14% chromium, 3.1% boron, 4.5% silicon, 4.5% iron, and 0.75% carbon, with a brazing range of 1950°F to 2200°F (1065°C to 1205°C), and is used for high-temperature applications such as aerospace components and heat exchangers.[reference:15]
BNi-1a contains approximately 14% chromium, 3.1% boron, 4.5% silicon, 4.5% iron, and 0.06% carbon, with a brazing range of 1970°F to 2200°F (1080°C to 1205°C), offering lower carbon content for reduced carbide precipitation.[reference:16]
BNi-2 contains approximately 7% chromium, 3.1% boron, 4.5% silicon, 3% iron, and 0.06% carbon, with a brazing range of 1850°F to 2150°F (1010°C to 1180°C), and is one of the most widely used nickel brazing filler metals for stainless steel and superalloy joining.[reference:17]
BNi-3 contains approximately 3.1% boron, 4.5% silicon, 0.5% iron, and 0.06% carbon, with a brazing range of 1850°F to 2150°F (1010°C to 1180°C), and is used for applications requiring high joint strength and good corrosion resistance.[reference:18]
BNi-4 contains approximately 1.9% boron, 3.5% silicon, 1.5% iron, and 0.06% carbon, with a brazing range of 1850°F to 2150°F (1010°C to 1180°C).[reference:19]
BNi-5 contains approximately 19% chromium, 10% silicon, and 0.03% carbon, with a brazing range of 2100°F to 2200°F (1150°C to 1205°C), and is used for high-temperature, corrosion-resistant joints.
BNi-5a and BNi-5b are variations of BNi-5 with modified chemistry for improved flow and reduced erosion.
BNi-6 contains approximately 11% phosphorus with the balance nickel, with a brazing range of 1700°F to 1800°F (925°C to 980°C), and is used for lower-temperature nickel brazing applications.
BNi-7 contains approximately 14% chromium, 10% phosphorus, and 0.03% carbon, with a brazing range of 1700°F to 1900°F (925°C to 1035°C), and offers excellent corrosion resistance and low melting temperature.
BNi-9, BNi-10, BNi-11, BNi-12, and BNi-13 are specialized classifications with varying chromium, boron, silicon, and other alloying additions for specific high-temperature and corrosion-resistant applications.
Which copper-zinc (RBCuZn) classifications are included?
The copper-zinc classifications in AWS A5.8 are RBCuZn-A, RBCuZn-B, RBCuZn-C, and RBCuZn-D, all of which are used for braze welding rather than brazing by capillary action.
RBCuZn-A contains approximately 59% copper, 0.6% tin, and the balance zinc, with a melting range of approximately 875°C to 895°C, and is used for braze welding of copper, steel, and cast iron.
RBCuZn-B contains approximately 58% copper with iron, tin, and manganese additions, and is particularly suitable for braze welding zinc-coated sheets without damaging the galvanized coating.
RBCuZn-C contains approximately 58% copper, 0.6% tin, and the balance zinc, with a melting range of approximately 870°C to 900°C, and is used for general braze welding applications.[reference:20]
RBCuZn-D contains approximately 48% copper with nickel and silicon additions, with a melting range of approximately 890°C to 920°C, and is used for high-strength braze welding of steel and cast iron.[reference:21]
These filler metals are commonly used in ventilation systems, automotive bodywork, pipe connections, bicycle and motorcycle frames, and general repair applications.[reference:22]
What Is BAg-8 and What Are Its Key Properties?
BAg-8 is a eutectic silver-copper brazing filler metal containing 72% silver and 28% copper, with a melting range of approximately 779°C to 899°C.
It is a cadmium-free filler metal with excellent flow characteristics and is widely used for brazing copper, nickel, and their alloys in vacuum and controlled atmosphere furnaces.
BAg-8 is particularly valued in the electronics and vacuum tube industries for its high electrical and thermal conductivity, as well as its excellent corrosion resistance.
It is also used for brazing stainless steel and other metals where precise temperature control and high joint integrity are required.
BAg-8a is a modified version containing approximately 0.4% lithium, which improves wetting on stainless steel and other difficult-to-braze metals.[reference:23]
Common trade names for BAg-8 include Sil-Fos 72, Lucas-Milhaupt Silvaloy 72, and Harris Stay-Silv 72.
What are the typical applications for BAg-8?
BAg-8 is used for brazing copper, nickel, and their alloys in vacuum and controlled atmosphere furnaces, particularly where high joint strength and leak-tightness are critical.
Typical applications include electronic vacuum tubes, waveguides, klystrons, accelerator components, and aerospace heat exchangers.
The filler metal is also used for brazing copper-to-copper joints in refrigeration and air conditioning systems where cadmium-free formulations are required.
BAg-8 is suitable for vacuum brazing because it contains no volatile alloying elements such as cadmium or zinc.
What is the difference between BAg-8 and BAg-8a?
BAg-8 and BAg-8a differ primarily in their lithium content and their wetting characteristics.
BAg-8 contains 72% silver and 28% copper without lithium, offering excellent flow and conductivity on copper and nickel alloys.
BAg-8a contains approximately 0.4% lithium in addition to the silver-copper eutectic composition, which improves wetting on stainless steels and other refractory metals by reducing surface oxides.[reference:24]
BAg-8a is preferred for brazing stainless steel and other alloys where oxide formation hinders wetting, while BAg-8 is preferred for copper and nickel-based assemblies where high electrical and thermal conductivity are paramount.
What Is BNi-2 and What Are Its Key Properties?
BNi-2 is a nickel-chromium-boron-silicon brazing filler metal containing approximately 7% chromium, 3.1% boron, 4.5% silicon, 3% iron, and 0.06% carbon, with a brazing temperature range of 1850°F to 2150°F (1010°C to 1180°C).[reference:25]
It is one of the most widely used nickel-based brazing filler metals due to its excellent combination of high-temperature strength, corrosion resistance, and flow characteristics.
BNi-2 produces joints with excellent oxidation resistance and high-temperature stability, making it suitable for aerospace, power generation, and chemical processing applications.
The filler metal is commonly used for brazing stainless steels, nickel-based superalloys, and cobalt-based alloys.
BNi-2 is available in powder, paste, tape, and foil forms to accommodate different brazing processes and joint configurations.
Common trade names include Lucas-Milhaupt BNi-2, Wall Colmonoy Nicrobraz 30, and Hoganas BNi-2.
What are the typical applications for BNi-2?
BNi-2 is used for brazing stainless steel and nickel-based superalloy components in aerospace and power generation applications, including turbine vanes, combustor liners, and heat exchangers.
It is also used for brazing components in chemical processing equipment, such as reactors, separators, and piping systems, where high-temperature corrosion resistance is required.
BNi-2 is suitable for vacuum brazing and controlled atmosphere brazing, making it compatible with a wide range of furnace brazing processes.
What is the difference between BNi-2 and BNi-5?
BNi-2 and BNi-5 differ primarily in their chromium content and brazing temperature requirements.
BNi-2 contains approximately 7% chromium, 3.1% boron, 4.5% silicon, and 3% iron, with a brazing range of 1850°F to 2150°F (1010°C to 1180°C).
BNi-5 contains approximately 19% chromium, 10% silicon, and 0.03% carbon, with a higher brazing range of 2100°F to 2200°F (1150°C to 1205°C).
BNi-5 provides better oxidation and corrosion resistance due to its higher chromium content, but requires higher brazing temperatures.
BNi-2 is more suitable for general-purpose brazing of stainless steels and superalloys, while BNi-5 is preferred for applications requiring maximum corrosion resistance at elevated temperatures.
What Is BCuP-5 and What Are Its Key Properties?
BCuP-5 is a copper-phosphorus-silver brazing filler metal containing approximately 15% silver, 5% phosphorus, and the balance copper, with a melting range of approximately 645°C to 800°C.
It offers a good balance of strength, flow characteristics, and moderate silver content, making it a popular choice for copper-to-copper and copper-to-brass brazing.
BCuP-5 is self-fluxing on copper, meaning it does not require a separate flux when brazing copper-to-copper joints, as the phosphorus content acts as a fluxing agent.
However, when brazing copper to brass or bronze, a suitable flux is required.
BCuP-5 is widely used in plumbing, HVAC, and refrigeration applications where leak-tight joints and good corrosion resistance are essential.
Common trade names include Sil-Fos 15, Lucas-Milhaupt Sil-Fos 15, and Harris Stay-Silv 15.
What are the typical applications for BCuP-5?
BCuP-5 is used for brazing copper-to-copper and copper-to-brass joints in plumbing, heating, ventilation, air conditioning, and refrigeration systems.
It is particularly suitable for brazing refrigeration tubing and compressor components, where the phosphorus content provides self-fluxing action on copper surfaces.
BCuP-5 is also used for brazing copper alloy fittings, valves, and heat exchanger components in the HVAC industry.
The filler metal is available in rod, wire, and preform forms to accommodate different joint configurations and brazing processes.
What is the difference between BCuP-3 and BCuP-5?
BCuP-3 and BCuP-5 differ primarily in their silver content and resulting melting characteristics and flow behavior.
BCuP-3 contains approximately 5% silver and 6% phosphorus, with a melting range of approximately 645°C to 815°C.
BCuP-5 contains approximately 15% silver and 5% phosphorus, with a melting range of approximately 645°C to 800°C.
BCuP-5 provides better flow characteristics and improved joint strength compared with BCuP-3 due to its higher silver content.
BCuP-5 is preferred for applications requiring maximum joint strength and leak-tightness, while BCuP-3 is more economical for general-purpose copper brazing.
What Are the Typical Applications for Each AWS A5.8 Alloy Family?
The application profiles of AWS A5.8 filler metals reflect their respective alloy systems and performance characteristics.
Aluminum-silicon (BAISi) filler metals are used for brazing aluminum and aluminum alloys in heat exchangers, air conditioning coils, and automotive components.
Silver (BAg) filler metals are used for brazing copper, steel, stainless steel, and nickel alloys across a wide range of industries, including HVAC, aerospace, electronics, and medical devices.
Copper-phosphorus (BCuP) filler metals are used for brazing copper and copper alloys in plumbing, refrigeration, and air conditioning systems.
Nickel (BNi) filler metals are used for brazing stainless steel and superalloys in aerospace, power generation, and chemical processing applications.
Copper-zinc (RBCuZn) filler metals are used for braze welding of steel, cast iron, and copper alloys in automotive, construction, and general repair applications.
Gold (BAu) filler metals are used for brazing electronic components, vacuum tubes, and aerospace assemblies requiring high reliability and oxidation resistance.
Magnesium (BMg) filler metals are used for brazing magnesium alloys in aerospace applications.
Understanding the operating conditions and material requirements of the component is essential for selecting the appropriate filler metal classification.
Aluminum-silicon filler metals (BAISi series) are used for brazing aluminum and aluminum alloys.
BAISi-4 is the most commonly used general-purpose aluminum brazing filler metal, containing approximately 12% silicon and 88% aluminum, with a brazing range of 1080°F to 1120°F.
BAISi-2 is used for brazing heat-treatable aluminum alloys such as 6061 and 6063.
BAISi-3 and BAISi-5 are suitable for torch brazing and furnace brazing, respectively.
BAISi-6 contains magnesium for brazing aluminum alloys that require enhanced corrosion resistance.
All of these filler metals require a suitable flux to prevent oxidation during brazing, as aluminum oxide forms rapidly at elevated temperatures.[reference:26]
Nickel-based (BNi series) and silver-based (BAg series) filler metals are commonly used for brazing stainless steel.
BNi-2 is widely used for brazing stainless steels and superalloys in aerospace and industrial applications due to its high-temperature strength and corrosion resistance.
BAg-8 and BAg-8a are used for brazing stainless steel in vacuum and controlled atmosphere furnaces, with BAg-8a containing lithium for improved wetting on stainless steel surfaces.
BAg-1 through BAg-7 are used for torch and induction brazing of stainless steel where lower brazing temperatures are acceptable.
The selection between nickel-based and silver-based filler metals depends on the required service temperature, corrosion resistance, and joint strength.
Copper-phosphorus (BCuP series) and silver-based (BAg series) filler metals are used for brazing copper and copper alloys.
BCuP-2, BCuP-3, and BCuP-5 are self-fluxing on copper and are widely used in plumbing and HVAC applications.
BAg-1 through BAg-8 are used for brazing copper-to-copper and copper-to-brass joints where higher strength or lower brazing temperatures are required.
BCuP-5 is particularly popular for refrigeration and air conditioning applications due to its excellent flow and leak-tightness.
When brazing copper to brass or bronze, a suitable flux is required even with self-fluxing copper-phosphorus filler metals.
Selecting the right AWS A5.8 brazing filler metal depends on the base metal composition, the required service temperature, the brazing process, and the corrosion resistance requirements.
The first step is to identify the base metal and select a filler metal that is metallurgically compatible and provides adequate joint strength.
The second step is to consider the service temperature: nickel-based and gold-based filler metals are suitable for high-temperature applications, while aluminum-silicon and copper-phosphorus filler metals are limited to lower temperatures.
The third step is to consider the brazing process: furnace brazing, torch brazing, induction brazing, and vacuum brazing each have different requirements for filler metal form and brazing temperature.
The fourth step is to consider the corrosion environment: nickel-based and silver-based filler metals generally offer better corrosion resistance than copper-phosphorus or copper-zinc filler metals.
The fifth step is to verify the filler metal availability in the required form, such as rod, wire, powder, paste, tape, or foil.
Always verify the filler metal selection with the applicable code requirements and the manufacturer's recommendations.
The first step is to determine the base metal composition and select the compatible filler metal family.
If the base metal is aluminum, select from the BAISi series.
If the base metal is copper or a copper alloy, select from the BCuP, BAg, or RBCuZn series depending on the joint configuration and brazing process.
If the base metal is stainless steel or a nickel-based superalloy, select from the BNi or BAg series.
The second step is to determine the brazing temperature range and ensure it is compatible with the base metal's heat treatment and service requirements.
The third step is to consider the brazing atmosphere: vacuum brazing requires vacuum-grade (BV) filler metals with low volatile content, while furnace brazing with a protective atmosphere can use standard classifications.
The fourth step is to verify the filler metal form and availability for the specific brazing process.
The fifth step is to confirm that the filler metal meets any applicable code or specification requirements.
The ASME F-Number is a grouping of filler metals based on their welding characteristics and usability, used in welding procedure qualification under ASME Section IX.
Brazing filler metals are not typically assigned F-Numbers in the same way as fusion welding filler metals, as brazing is a separate joining process with its own qualification requirements under ASME Section IX, Part QB.
The A-Number is a grouping based on the chemical composition of the deposited weld metal, used for procedure qualification of ferrous materials.
For brazing filler metals, the A-Number may not be directly applicable.
The exact qualification requirements should be verified with the latest edition of ASME Section IX.
AWS A5.8 is part of a broader family of AWS filler metal specifications and is closely related to international brazing standards.
Understanding these related standards helps ensure that the correct specification is applied for each brazing process and base metal.
The main related standards are ISO 17672, AWS A5.31, AWS A5.27, and AWS A5.10.
Each covers different product forms, alloy systems, or brazing processes.
What is ISO 17672?
ISO 17672 is the international standard that specifies the compositional ranges of a series of filler metals used for brazing.
The filler metals are divided into seven classes based on their composition, and the standard attempts to amalgamate European, American, and Japanese brazing standards into a single international framework.[reference:27]
The current edition is ISO 17672:2024, which was approved in April 2024 and replaces the 2016 edition.
Many AWS A5.8 classifications have corresponding ISO 17672 designations; for example, BAg-8 corresponds to ISO 17672 Ag 272, and BAg-1 corresponds to Ag 345.[reference:28]
The correspondence is product-specific and should be verified with the manufacturer's datasheet and the latest editions of both standards.
What is AWS A5.31/A5.31M?
AWS A5.31/A5.31M is the specification for fluxes for brazing and braze welding.[reference:29]
It prescribes the requirements for classification of brazing fluxes based on their chemical composition and intended use.
Brazing fluxes are used to remove oxides and prevent oxidation during the brazing process, particularly when brazing in air with a torch or furnace.
Verify with the latest edition for current classifications.
What is AWS A5.27?
AWS A5.27 covers copper and copper-alloy bare welding rods for oxyfuel gas welding.
The specification includes classifications such as RCu, RCuSi-A, RCuSn-A, and RBCuZn-A through RBCuZn-D.
These rods are used with the oxyfuel gas welding process and are related to the RBCuZn braze welding classifications in AWS A5.8.
Verify with the latest edition for current classifications.
What is AWS A5.10/A5.10M?
AWS A5.10/A5.10M covers bare aluminum-alloy electrodes and rods for gas metal arc, gas tungsten arc, oxyfuel gas, and plasma arc welding.
The specification includes classifications such as ER4043, ER5356, and ER1100, which are used for fusion welding of aluminum, as distinct from the BAISi brazing filler metals in AWS A5.8.
Verify with the latest edition for current classifications.
Where Can I Find the Official Complete List of AWS A5.8 / A5.8M Types?
The authoritative source for the complete list of AWS A5.8/A5.8M classifications is the latest edition of the specification itself, available from the American Welding Society at pubs.aws.org or through authorized standards distributors such as ANSI.[reference:30]
The specification includes detailed tables covering chemical composition requirements, liquidus and solidus temperatures, brazing temperature ranges, recommended applications, physical form, sizes, and packaging requirements for every classification.[reference:31]
Manufacturer technical datasheets and brazing filler metal catalogs also list AWS A5.8 classifications, but these should be cross-referenced against the official specification for accuracy.
Because classifications may be added or revised with each edition, always verify with the latest A5.8/A5.8M edition to ensure your filler metal selection aligns with the current classification list.
