SIST EN 14324:2004

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Trdo spajkanje – Navodilo za uporabo spajkanih spojevHartlöten - Anleitung zur Anwendung hartgelöteter VerbindungenBrasage fort - Guide d'application pour les assemblages réalisés par brasage fortBrazing - Guidance on the application of brazed joints25.160.50Trdo in mehko lotanjeBrazing and solderingICS:Ta slovenski standard je istoveten z:EN 14324:2004SIST EN 14324:2004en01-november-2004SIST EN 14324:2004SLOVENSKI
STANDARD



SIST EN 14324:2004



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14324September 2004ICS 25.160.50 English versionBrazing - Guidance on the application of brazed jointsBrasage fort - Guide d'application pour les assemblagesréalisés par brasage fortHartlöten - Anleitung zur Anwendung hartgelöteterVerbindungenThis European Standard was approved by CEN on 9 July 2004.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14324:2004: ESIST EN 14324:2004



EN 14324:2004 (E) 2 Contents page Foreword.4 Introduction.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Joint design.8 4.1 Principle.8 4.2 Types of joint.8 4.3 Assembly gap and brazing gap.9 4.3.1 General.9 4.3.2 Influence of brazing filler materials.11 4.3.3 Influence of parent material.11 4.3.4 Influence of dissimilar parent materials.11 4.3.5 Influence of surface finish.12 4.3.6 Influence of atmospheres or fluxes.13 4.4 Surface preparation.13 4.5 Stress distribution in service.13 4.6 Application of filler material.13 4.7 Assembly.13 4.8 Good brazing design.13 5 Materials.14 5.1 Parent materials.14 5.1.1 Basic considerations.14 5.1.2 Special considerations.14 5.2 Filler materials.17 5.2.1 General.17 5.2.2 Forms available.18 5.2.3 Applications.18 5.3 Fluxes.19 5.3.1 General.19 5.3.2 Flux removal.19 5.4 Atmospheres.20 5.4.1 Protective.20 5.4.2 Vacuum atmospheres for brazing.20 5.5 Safety.20 6 Methods of brazing.22 7 Heat treatment.22 8 Inspection.22 Annex A (informative)
Examples of brazed assemblies.23 Annex B (informative)
Typical examples of joint design.26 Annex C (informative)
Filler materials most commonly used for combinations of parent materials.32 SIST EN 14324:2004



EN 14324:2004 (E) 3 Annex D (informative)
Suitability of brazing filler material classes for the commoner brazing methods.33 Annex E (informative)
Methods of brazing.34 E.1 Flame brazing.34 E.1.1 General.34 E.1.2 Hand torch brazing.34 E.1.3 Mechanized flame brazing.36 E.2 Induction brazing.37 E.2.1 Process.37 E.2.2 Application.38 E.2.3 Advantages/limitations.38 E.2.4 Size limitations.38 E.2.5 Safety.38 E.3 Resistance brazing.39 E.3.1 Process.39 E.3.2 Application.39 E.3.3 Advantages/limitations.39 E.3.4 Size limitations.39 E.3.5 Safety.40 E.4 Furnace brazing.40 E.4.1 Process variants.40 E.4.2 Protective atmosphere brazing.40 E.4.3 Vacuum brazing.42 E.5 Immersion brazing.43 E.5.1 General.43 E.5.2 Flux bath brazing.43 E.5.3 Dip bath brazing.44 E.5.4 Salt bath brazing.45 E.6 Special methods.46 E.6.1 Laser beam brazing.46 E.6.2 Brazing/braze welding with an arc.47 E.6.3 Other methods.47 Bibliography.48
SIST EN 14324:2004



EN 14324:2004 (E) 4 Foreword This document (EN 14324:2004) has been prepared by Technical Committee CEN/TC 121 “Welding”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2005, and conflicting national standards shall be withdrawn at the latest by March 2005.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
SIST EN 14324:2004



EN 14324:2004 (E) 5 Introduction The purpose of this document is to provide information and guidance to users whose knowledge of brazing is limited, either as regards the whole process or in some specific areas. It is not intended to replace textbooks but to make readily available certain important information and hopefully prevent some common errors. Brazing techniques offer a wide field for joining, cladding, building up and comparable applications where brazing filler materials can be used. Structures similar to brazed joints can be achieved by arc brazing processes (MIG, TIG, plasma), infra-red brazing and electron beam brazing, which are better described as braze welding. Where the word 'material' is used for components, they can be metallic or non-metallic, except when the component can only be metallic, when it is so described. The same usage applies to filler materials, although the use of non-metallic filler materials is very limited. SIST EN 14324:2004



EN 14324:2004 (E) 6
1 Scope This document gives guidance on the application of brazing and the manufacture of brazed joints. This standard gives an introduction to brazing and a basis for the understanding and use of brazing in different applications. Because of the wide range of applications of brazing this standard does not give detailed guidance that might be product specific. For such information reference should be made to the appropriate product standard or, for applications where this does not exist, the relevant criteria should be clearly established before any brazing is undertaken. This standard covers joint design and assembly, material aspects for both parent material and filler materials, brazing process and process variables, pre- and post-braze treatment and inspection. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1044:1999, Brazing — Filler metals. EN 1045, Brazing — Fluxes for brazing — Classification and technical delivery conditions. EN 12797, Brazing — Destructive tests of brazed joints. EN 12799, Brazing — Non-destructive examination of brazed joints. EN 13133, Brazing — Brazer approval. EN 13134, Brazing — Procedure approval. EN ISO 18279, Brazing — Imperfections in brazed joints (ISO 18279:2003). 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 brazing joining process in which a filler material is used which has a liquidus temperatur above 450 °C, but below the solidus of the parent material, and which is mainly distributed in the brazing gap by capillary attraction NOTE Other joining methods exist (see E.6.3). 3.2 brazed joint result of a joining process where the parent materials are not melted and the filling material and braze material have different chemical compositions compared to the parent materials 3.3 brazing gap narrow, mainly parallel gap at the brazing temperature between the components to be brazed (see Figure 1 and 4.3.4) SIST EN 14324:2004



EN 14324:2004 (E) 7 3.4 assembly gap fit up narrow, mainly parallel gap at room temperature between the components to be brazed (see Figure 1 and 4.3.4)
ABg1g2 g2 < g1 a) Constrained butt joint ABg1g2 g2 > g1 Shaded component has higher coefficient of expansion. b) Tube joint (dissimilar materials) Key A Assembly at ambient temperature B Assembly at brazing temperature g1 Assembly gap g2 Brazing gap Figure 1 — Assembly gap and brazing gap SIST EN 14324:2004



EN 14324:2004 (E) 8 4 Joint design 4.1 Principle The brazing process depends upon capillary flow of a molten brazing filler material between parts separated by a narrow gap. The filler material has a different composition from the components to be brazed. This compositional difference may affect the properties of the assembly in service, e.g. at elevated temperature, in corrosive media or under fatigue loading. In addition the properties of the parent material of the components to be brazed can be affected by the brazing cycle. 4.2 Types of joint There are basically two types of joint as shown in Figure 2. In practice very few assemblies are as simple as the basic types shown in Figure 2 (see annex A).
a) Lap
b) Butt Figure 2 — Basic joint types Lap joints are generally used because they are easier to fabricate and offer increased strength. Butt joints are used where adequate strength is readily obtained, e.g. where the mechanical properties of the parent materials are lower than those of the brazed joint, or where the thickness and/or length of a lap joint is undesirable. It should be noted that the useful overlap for a lap joint in shear is related to the thickness of the thinner component; beyond the optimum overlap there is little to be gained in joint strength by increasing the overlap length. SIST EN 14324:2004



EN 14324:2004 (E) 9 4.3 Assembly gap and brazing gap 4.3.1 General The areas of a brazed assembly are defined as shown schematically in Figure 3. Perhaps the most critical feature in brazing is the control of the brazing gap, i.e. the gap at the brazing temperature, between the components to be brazed and through which the filler material has to flow by capillary action. There are several factors that influence the choice of the brazing gap and which have to be taken into consideration. It is essential to recognise that where joints are to be made between different parent materials, the assembly gap (fit up) will usually have to be different from the brazing gap (see 4.3.4). NOTE The assembly gap may need to be larger or smaller than the brazing gap, depending on the thermal expansion coefficients of the materials, the configuration and the brazing process. Different filler materials require different gaps even within the same group, as can be seen from the typical ranges given in Table 1, but the optimum gap may also be affected by a number of other joint parameters (see example in Figure 4), e.g.:  parent material(s);  geometry of the joint;  surface finish of the faying surfaces;  use of a flux or protective atmosphere;  careful control of brazing temperature and heating rate;  brazing process.
Table 1 — Typical brazing gaps Filler material class according to EN 1044 Brazing gapa mm AL 0,05 to 0,25 AG 0,05 to 0,30 CP 0,05 to 0,30 CU1XX CU2XX & CU3XX Up to 0,15 0,05 to 0,20 NI Up to 0,15 AU Up to 0,10 a Brazing gap will depend on the selected filler materials, the brazing process and the brazing conditions.
SIST EN 14324:2004



EN 14324:2004 (E) 10
a) Simple brazed assembly
Key
Parent material
Parent material affected by brazing (heat affected zone (HAZ))
Diffusion-transition zone
Braze material
NOTE Extent of HAZ will vary with materials and brazing process. b) Section through assembly in a) Figure 3 — Schematic of brazed assembly
SIST EN 14324:2004



EN 14324:2004 (E) 11 012
Key 1 Mechanized flame brazing with flux 2 Hand flame brazing with flux Figure 4 — Schematic of differences in brazing gap ranges with different brazing processes (in this example for mild steel brazed with an AG filler materials) 4.3.2 Influence of brazing filler materials Those types with the shortest melting range, often containing significant additions of temperature depressant elements (e.g. Si, B, P and Zn) exhibit enhanced fluidity and excellent capillary penetration. This also applies to most eutectic compositions and many pure metals. Conversely, those filler materials having wide melting ranges will generally have better wide gap filling characteristics and are more suitable for brazing when gaps are at the upper end of the stated range. 4.3.3 Influence of parent material For those parent materials that are not readily soluble in the brazing filler material, or do not undergo mutual interaction to form alloy layers, gaps may, in general, be tighter than with those combinations where significant alloying occurs. Extensive inter-alloying will impair the fluidity of the brazing filler material and necessitate the use of wider brazing gaps to ensure complete penetration of the joint by the brazing filler material. 4.3.4 Influence of dissimilar parent materials When dissimilar parent materials, of different coefficients of thermal expansion, are to be joined, care has to be exercised in designing the joint in order to obtain the correct brazing gap (see Figure 5). In extreme cases, joint gaps may close completely or open excessively at brazing temperature resulting in non-penetration or non-retention of the brazing filler material, respectively. Given that the brazing gap is the essential parameter, the assembly gap (to which the components will be machined) has to be calculated from the expansion coefficients of the parent materials, the sizes of the components and the brazing temperature. This problem becomes greater:  as the size of the brazed assembly increases;  as the brazing temperature becomes higher;  as the thermal expansion differential widens. SIST EN 14324:2004



EN 14324:2004 (E) 12 badsdm12BA Key 1 Molybdenum 2 Steel A Assembly at ambient temperature B Assembly at brazing temperature ds Outer diameter of steel part (before brazing) dm Inner diameter of molybdenum part (before brazing) a Assembly gap b Brazing gap
Thermal expansion coefficient . . steel > . molybdenum
Figure 5 — Influence on the brazing gap of dissimilar parent materials with different thermal expansion coefficients (schematic) 4.3.5 Influence of surface finish Too coarse or too fine a surface finish will adversely affect the filling of the joint gap. The flow of the filler material may be influenced by the surface finishes of the joint materials. SIST EN 14324:2004



EN 14324:2004 (E) 13 4.3.6 Influence of atmospheres or fluxes Processes using a protective atmosphere or a vacuum will tolerate tighter joint gaps, with given brazing filler materials, than an equivalent process where a flux is used. Unless joint gaps are adequate, flux and gas pockets will be by-passed and become entrapped in the finished joint. 4.4 Surface preparation The component parts of a joint should be clean and properly fitting. When required by the brazing method, oxide, grease and oil should be removed by chemical, thermal and/or mechanical methods. This may involve degreasing, pickling, scratch brushing and other similar processes. The surface of the component within the brazed joint should not be polished. A roughened surface will assist filler materials flow particularly in the direction of machining. To improve the fit-up it may be necessary to modify the surface by methods such as knurling. To improve wettablilty of materials such as nickel alloys containing titanium and aluminium, and ceramics, it may be necessary to cover the surfaces with a suitable material, e.g. by plating or metallizing. To prevent the flow of filler materials outside the joint area, it may be necessary to apply a 'stopping-off' agent. Care should be taken that this does not penetrate into the capillary joint gap and inhibit flow. The degree of cleanliness required depends upon the ultimate quality required of the component and also the brazing process to be used. The degree of preparation is most severe for flux-free controlled atmosphere brazing at higher temperatures. 4.5 Stress distribution in service Figure B.1 illustrates design modifications which endeavour to remove high stress concentrations from joint edges and distribute the stress more evenly in the parent materials. 4.6 Application of filler material The brazing filler material is available in various forms (see 5.2.2). For hand torch brazing applications, the brazing filler material is generally hand fed as rod or wire but may be pre-placed. In mechanized brazing applications, the brazing filler material is either pre-placed or automatically fed. In furnace brazing it has to be pre-placed. Examples of filler material placement are shown in Figure B.2. The point at which the filler material is applied can greatly affect the quality of the joint. Internal pre-placement can also serve to demonstrate that capillary flow through the joint has occurred. 4.7 Assembly It is essential, when designing joints, to ensure that the component parts will retain the required relationship during the brazing process. There are several effective methods of achieving this (see Figure B.3). 4.8 Good brazing design Examples of good brazing design are given in Tables B.1 and B.2. SIST EN 14324:2004



EN 14324:2004 (E) 14 5 Materials 5.1 Parent materials 5.1.1 Basic considerations The wide range of materials in current use precludes the listing of every grade which is amenable to joining by the brazing process. General categories are listed here for guidance purposes but other less common materials may well be applicable. If an unlisted material is specified, advice should be sought from the brazing filler manufacturer. a) Aluminium and its alloys. Pure aluminium, aluminium-zinc (< 6 %), aluminium-manganese (< 2 %), aluminium-silicon (< 2 %), aluminium-magnesium (< 2 %). b) Coated materials. Materials with electrodeposited or other coatings. c) Cobalt and its alloys. Pure cobalt, hard facing alloys, corrosion-resistant alloys. d) Copper and its alloys. Copper (unalloyed, phosphorus-bearing, silver-bearing), low alloyed copper alloys (formerly designated as e.g. beryllium-copper, chromium-copper and others), copper-zinc alloys (brasses), copper-tin alloys (tin-bronzes/ phosphor-bronzes, including some gunmetals), copper-tin-lead alloys (including some gunmetals), copper-nickel-zinc alloys (nickel-silvers), copper-nickel-alloys (cupro-nickel), copper-aluminium alloys (aluminium bronzes), copper-manganese-aluminium alloys. e) Ferrous metals. Cast iron, malleable iron, mild steel, carbon and low alloy steels, alloy steels, high speed and tool steels, stainless, heat and corrosion-resistant steels. f) Nickel and its alloys. Pure nickel, nickel-copper, nickel-iron, nickel-chromium-iron, nickel-chromium. g) Precious metals. Gold, platinum, palladium, silver and their alloys. h) Refractory metals and alloys. Titanium, zirconium, tantalum, niobium and their alloys. i) Tungsten and molybdenum. Tungsten, molybdenum, cemented carbides, silver–tungsten, copper-tungsten. j) Non-metallic materials. For example, ceramics, graphite, tungsten carbide, diamonds, cermets, glass, sapphire. 5.1.2 Special considerations 5.1.2.1 General Some of the parent materials listed in 5.1.1 may have their properties adversely affected by the brazing process, either because of the effects of temperature or because of metallurgical interactions. In addition, consideration needs to be given to the effects that may arise in the brazing of dissimilar materials. Therefore, the points in 5.1.2.2 to 5.1.2.13 need to be considered when the brazing of such materials is proposed.
SIST EN 14324:2004



EN 14324:2004 (E) 15 5.1.2.2 Dissimilar parent materials One advantage of brazing is that many combinations of parent materials can be joined, but the effects of the brazing cycle on their physical and metallurgical characteristics always need to be considered. The primary physical property to be considered is the coefficient of thermal expansion. This has two main effects. The gap between the components at brazing temperature will not be the same as
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