Download - En P 01 PrinciplesOfBrazingTechnology
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
1/14
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
2/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
Brazing is a thermal process for securely joining andcoating materials, whereby a liquid phase isproduced by melting a brazing alloy (fusion-brazing)or by diffusion at the interfaces (diffusion-brazing).The solidus temperature of the base material is notreached (DIN 8505, Part 1).
1. Standards and regulations for brazing1.1 Recommendations for brazing
- Technical information sheets- Standards
Technical information sheets: Recommended
These are prepared by experts in work groups and
the information corresponds to the respective state oftechnology. It is recommended that the technicalinformation sheets be heeded as they are alsoviewed as the respective state of the technology froma legal point of view.
Examples:
- DVS-Guideline 1183: DVS-course Brazingcopper materials
- VdTV Technical Information Sheet 1160:Evaluation of processes for manufacturing
brazed joints and high temperature brazedjoints
- DVGW Work Sheet GW2
Standards: Compulsory
Any deviation from the standard must be specificallyagreed between the client and contractor. There arecurrently many national (DIN), european (EN) andinternational (ISO) standards. The existing Germanstandards are being superseded by Europeanstandards. Referral is made in particular here to DIN
EN 1044 Brazing composition of brazingalloys which replaces DIN 8513 Parts 1-5 and toDIN EN 1045 Brazing fluxes for brazing whichreplaces DIN 8511-1. Both these standardscategorise the respective materials. There are alsostandards in existence which cover the terms used inbrazing, constructional aspects, testing of brazedjoints, inspecting brazed joints, etc. which can beobtained via Beuth-Verlag (Berlin) or DVS-Verlag(Dsseldorf).
1.2 Regulations for work safety and accidentprevention, e.g.:- Accident prevention regulations, section 15:
Welding and related techniques d.BG;- VDI 2046 Safety guidelines for operating
industrial furnaces with inert gas and reactiveatmospheres
2. Wetting process and capillary forces
2.1 Distinction between welding and brazing
In welding not only is the added alloy material meltedbut the base material is also partially melted.
In brazing only the added brazing alloy melts. Thebase material is wetted in its solid state by the liquidbrazing alloy.
Usually similar materials Virtually any desired materialcombinations
Fusion welding Brazing
Virtually identical melting Brazing alloy melts attemperatures for the base lower temperaturematerial and alloy than the base material
2.2 Wetting
A prerequisite for brazing is the wetting of the base
material by the brazing alloy. Three importantconditions must be fulfilled for this to happen: the brazing surfaces and the brazing alloy must
be bare metal, the brazing surfaces and the brazing alloy must
have at least reached the working temperature, at least one component of the brazing alloy must
readily form an alloy with the base material.
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
3/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
Base material
- Visible oxide layers (rust and scale), fat layers
and layers of dirt must be removed beforecarrying out brazing work. Thin oxide layers (e.g.tarnishing) may remain on the workpieces ifbrazing is carried out using a flux.
- The working temperature is the lowest surfacetemperature of a workpiece at the brazing joint at
which the brazing alloy can wet, spread and bondwith the base material. This temperature is alwayshigher than the solidus temperature of the brazingalloy. It can be above, below or the same as itsliquidus temperature.
- The wetting process involves surface alloyingbetween the brazing alloy and the base material.Next to the wetting zone there is a diffusion zonewhich is very small for brazing work and cannotbe detected by metallographic means. In order toattain optimum strength, the brazing alloy must beliquid for at least 8 to 10 seconds to give an
adequately deep diffusion zone.
There is greater interaction between the brazing alloyand base material when carrying out hightemperature brazing (flux-free brazing attemperatures above 900C in a controlledatmosphere).
2.3 Joint-brazing and gap-brazing
Joint-brazing is a brazing technique similar to gas-fusion welding from a joint preparation and working
method point of view. It is virtually always carried outmanually. The working temperature of the brazingalloy must not be exceeded when joint-brazing.
1 to 1.5 mm
The most important area of application of joint-brazing is for brazing galvanised steel pipes.
The workpieces are prepared for gap-brazing such
that the brazing joints are narrow capillary gaps.They are heated up to brazing temperature uniformlyover the whole length of the gap. The liquid brazingalloy is forced into the gap by capillary fillingpressure. This technique is easy to mechanise. Themajority of brazing work is carried out by the gap-brazing technique.
The surface forces are additive in the narrowcapillary gaps (size of the order of 0.1 mm), so thatthe brazing alloy is preferentially drawn into thenarrow gap. If brazing is being carried out with a fluxin a gas atmosphere, the brazing alloy which
penetrates into the brazing gap must be able to pushthe flux out of the gap.
In gap-brazing, the working temperature of thebrazing alloy may be exceeded by in general 20 to50C.
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
4/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
ar o e we ng n erme ae sa e
Final stateII = Workpiece 1II = Workpiece 2
Both bare metal, andheated to workingtemperatureLiquid brazing alloy
Capillary filling pressure
The brazing alloy is pressed into the gap by capillaryforces. The narrower the brazing gap, the higher thecapillary filling pressure.
For a 0.1 mm parallel gap, the capillary fillingpressure reaches ca. 100 mbar, corresponding toabout 0.1 Atm. This in turn corresponds to about a 1m column of water ( = 1); assuming = 10 g/cm3(the density of a brazing alloy), the capillary heightfor low melting point brazing alloys in a 0.1 mm widegap can be calculated to be ca. 10 cm. This agreesreasonably well with experiences in practice.
(only applies forbrazing with flux)
Gap too narrow
Correct gap width
Permissible gap width for manual brazing
Gap too wide
Different gap cross-sections give different fillingpressures. An open fillet has a six times highercapillary filling pressure than a parallel flat gap.
3. Brazing alloy and flux groups
3.1 Brazing alloys
According to DIN 8505, alloys with a liquidustemperature below 450C are solders and those witha liquidus temperature above 450C are brazingalloys.
The upper and lower brazing temperature limits aredetermined by the following:
lower limit- the working temperature
upper limit
- the flux (becomes saturated with oxides attoo high temperatures), or
- the brazing alloy (individual components ofthe alloy can evaporate), or
- the economics of the process (unnecessarilyhigh temperatures cost unnecessary timeand energy), or
- the base material (structural transformation;strength loss).
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
5/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
3.2 Fluxes
Fluxes are solvents for metal oxides. They have aneffective temperature range within which they areable to dissolve metal oxides. The solvating capacityof the flux is limited. About 5% of the weight of flux in
metal oxides can be dissolved. If oxides are presentin greater amounts, the flux saturates and it loses itsfunctionality.
Atmosphericoxygene Flux Oxide
More than 5 min.
The hygroscopic flux residues must be removed byscouring in water or by pickling in pickling bathssuitable for the base materials. Ultrasound aids theremoval of these flux residues.
The non-hygroscopic flux residues do not have to beremoved for fear of corrosion. If they need to beremoved for other reasons (e.g. to paint thecomponents), they are usually removed by
mechanical means (e.g. sand-blasting).Too little Sufficient
Oxide film remains Oxide film is
dissolved
The solvating capacity of modern brazing fluxes foruse at low temperatures (i.e. between 600 and800C) for common heavy metal oxides is between 1and 5%, meaning that it is limited. That means thatrelative to the oxide which is present a relativelylarge amount of flux must be available, and ultimatelyso in the molten state, otherwise sound brazing workis not achieved. Extremely narrow gaps, e.g. lessthan 0.02 mm, hence cause problems because thereis an inadequate amount of flux in the gap. This
naturally has a big effect on the soundness of thebrazed joint.
Flux
Wire of brazing alloy
For surface brazing, the high capillary filling pressurein the open fillets leads to running of the brazing alloyon the external sides. The supply of brazing alloy tothe narrow surface gap is reduced; increasedinclusion of flux hence occurs.
Brazing alloyFlux
Increased flux inclusion can be avoided by insertedbrazing alloy sheet.
Gaseous fluxes
Joints (V-seams and fillets) can be brazed usinggaseous fluxes. For brazing gaps especially forgaps having larger depths and small widths the useof gaseous fluxes is not recommended because theflame does not penetrate into the capillary gap.When using flux pastes, their working life can besignificantly prolonged by the additional use ofgaseous fluxes.
The effective temperature of gaseous fluxes extendsfrom about 750C to 1100C.
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
6/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
Brazing with flux-forming brazing rods - BrazeTecSilfos brazing alloys.
OxygenFuel gas
Copper alloys, copper-tin alloys and silver can bebrazed with phosphorus-containing brazing alloyswithout the use of flux. The self-flowing properties
of these brazing alloys can be explained as follows:On melting the brazing alloy, the phosphorus in thebrazing alloy reacts with oxygen in the air to formphosphorus pentoxide. This reacts with the copperprotoxide on the copper surface to form coppermetaphosphate which acts as a flux. As coppermetaphosphate is safe from a chemical- corrosionpoint of view, the brazed joints require nosubsequent treatment.
When brazing with BrazeTec Silfos brazing alloys,the brazing time should not be longer than about 3 to
4 minutes.
4. Brazability of components
According to DIN 8514, the brazability is the propertyof a component to be manufactured in such a wayvia brazing that it meets the stipulated requirements.
A component can be brazed if the followingconditions are met (see diagram):
- the base material is suitable for brazing,- there is a brazing capability for the
manufacture, namely one or more brazingtechniques can be used,
- and the construction can be brazed such thata sound construction results, namelysatisfactory reliability of the componentunder the foreseen operating conditions.
Comment: In electrical engineering, the expressionssolderability and suitability for soldering are usedsynonymously for soldering.
Suitable base material, brazing alloy and fluxcombinations
Each of the three properties suitability for brazing,brazing capability and ability to manufacture asound brazed joint depend on the base material,manufacturing process and joint design. The degreeof dependency on these three parameters dependson the individual brazing task.
Brazabilityof the
component
Brazingcapability
Manufacture
Soundness ofthe brazed joint
Construction
Base material
Suitability forbrazing
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
7/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.BrazeTec.de
The suitability of base materials for brazing work isshown in Table 1.
Tables 1 and 3 give information about how theindicated materials can be brazed. This does notmean to say that components brazed in this way can
withstand all operating loads. In order to guaranteethis, the operating conditions for the brazed jointsmust be known prior to selecting theconditions/methods for carrying out the brazing work.These are workpiece-specific and differ from onecomponent to the next. More detailed information on
this matter can be found in the section entitledSelection criteria for brazing alloys and fluxes. Incertain instances where there is relatively high risk ofdamage, we recommend that you get in touch withus to enable optimum selection of the brazingparameters.
Brazing has the big advantage that virtually allmaterials which are suitable for brazing can becombined with each other. It goes without saying thatthe brazing parameters must always be selected forthe most difficult material from a brazing point ofview.
Suitability of base materials for brazing
Group 1 Group 2 Group 3
Materials which can be brazed withuniversal brazing alloys and universalfluxes and using all standardtechniques.
e.g.copper and copper alloysnickel and nickel alloysiron materialscommon steelscobalt
noble metals
Materials which require specialbrazing alloys and/or special fluxes,but which do not require specialbrazing techniques.
e.g.aluminium and aluminium alloyshard metals, stelliteschromium, molybdenum, tungsten,tantalum, niobiumsolder-like materials
Materials which can only bebrazed using special brazingalloys and special techniques.
e.g.titaniumzirconiumberylliumceramics
Table 1
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
8/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Solder and brazing alloy groups (I)
Group description Soldering /brazing
temperaturerange
C
Typical solders /brazing alloys in thisgroup in accordance
with EN (DIN)
BrazeTec name Solidustemp.
C
Liquidustemp.
C
Max. permcontinuoperat
temperat
CTin-lead soldersEN 29453
145 ... 325 S-Sn60Pb40S-Pb50Sn50
183183
190215
8080
Special soldersEN 29453
145 ... 395 S-Sn97Cu 3
S-Sn96Ag4S-Sn96Ag3
S-Sn95Sb5
Soldamoll 230(BrazeTec 3)Soldamoll 220BrazeTec 4
Soldamoll 235
230
221
250
221
240
110
110
110
Cadmium-freeuniversal brazingalloys
DIN EN 1044(DIN 8513)
650 ... 1100
AG 104 (L-Ag45Sn)AG 106 (L-Ag34Sn)AG 203 (L-Ag44)AG 207 (L-Ag12)
CU 303 (L-CuZn40)
CU 102 (L-Cu)
BrazeTec 4576BrazeTec 3476BrazeTec 4404BrazeTec 1204
BrazeTec 60/40
640630675800
875
1083
680730735830
895
1083
200200300300
350
Low melting pointcadmium-containing universalbrazing alloysDIN EN 1044(DIN 8513)
610 ... 800 AG 304 (L-Ag40Cd)AG 306 (L-Ag30Cd)
BrazeTec 4003BrazeTec 3003
595600
630690
150150
Manganese-containing specialbrazing alloysDIN EN 1044(DIN 8513)
690 ... 1020 AG 502 (L-Ag49) BrazeTec 4900BrazeTec 21/68
680980
7051030
400600
1) not laid down in standards
Table 2a
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
9/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Solder and brazing alloy groups (II)
Group description Soldering /brazing
temperature
range
C
Typical solders /brazing alloys in thisgroup in accordance
with EN (DIN)
BrazeTec name Solidustemp.
C
Liquidustemp.
C
Max. pcontope
tempe
Phosphorus-containing brazingalloys for copperbase materialsDIN EN 1044(DIN 8513)
710 ... 800 CP 102 (L-Ag15P)
CP 105 (L-Ag2P)CP 203 (L-CuP6)
BrazeTec Silfos 15
BrazeTec Silfos 2BrazeTec Silfos 94
645
645710
800
825890
150
150150
Special brazingalloys for specialbrazing workDIN EN 1044
(DIN 8513)
730 ... 960 AG 403 (L-Ag56InNi) BrazeTec 5603BrazeTec 6009BrazeTec 7200
600600780
710720780
200200300
High temperaturenickel-basedbrazing alloysDIN EN 1044(DIN 8513)
900 ... 1200 Ni 107 (L-Ni7)Ni 105 (L-Ni5)Ni 102 (L-Ni2)
BrazeTec 897BrazeTec 1135BrazeTec 1002
8901080970
89011351000
Aluminium brazingalloysDIN EN 1044(DIN 8513)
560 ... 600 AL 104 (L-AlSi12) BrazeTec 88/12 575 590 200
Table 2b
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
10/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Flux groups (I) for soldering/brazing metallic materials
Flux group Flux type Information about the manufacture Most important areas of application 3.2.2.
3.1.1.
Zinc chloride and/or ammoniumchloride and free acids
Zinc chloride and/or ammoniumchloride
Chromium-containing steels;highly oxidised workpieces
Chromium-free steels and non-noble metalswashing off the residues is possible
3.1.1.
2.1.3
2.1.1
2.1.2.
Zinc chloride and ammoniumchloride in organic formulation
Organic acids
Amines, diamines, urea
Organic halogen compounds
Chromium-free steels and non-noble metalswashing off the flux residues is not possible
Fluxes forsoldering heavymetalsDIN EN 29454
1.1.2.
1.1.1.
1.1.3.
Resins with halogen-containingactivators
Resins without additives
Resins withhalogen-free additives
Copper
Fluxes forsoldering lightmetalsDIN EN 29454
3.1.1.
2.1.3.
2.1.2.
Solder-forming zinc chloridesand/or tin chlorides;also with additives
Organic compounds
Organic halogen compounds
For workpieces which can be washed
Table 3a
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
11/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Flux groups (II)
Flux group Flux type Information about themanufacture
Most important areas of application
Fluxes for brazingheavy metals
DIN EN 1045
FH10FH11
FH12
FH20FH21
FH30
FH 40
Boron compounds and fluorides
Boron compounds
Boron compounds, phosphates,silicates
Chlorides and fluorides
Silver brazing alloys with working temperaturesca. 800C
Brazing alloys with working temperatures betwe750 and ca. 1000C
Brazing alloys with working temperatures above1000C
Brazing alloys with working temperatures betwe600 and 1000C for reactor construction (boron
Fluxes for brazing
light metalsDIN EN 1045
FL10
FL20
Hygroscopic chlorides and
fluoridesNon-hygroscopic fluorides
For workpieces which can be washed (also pick
neutralised)Heat exchangers
Table 3b
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
12/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Proposals (I) for brazing alloy (solder) / flux / brazing (soldering) technique combinations (for Group 1 base ma
Base material Brazing alloy Flux Technique *) Solder Cu CP 105 (L-Ag2P)
CP 203(L-CuP6)--
Cu-alloys CP 105 (L-Ag2P)
AG 102 (L-Ag55Sn)AG 203 (L-Ag44)
FH10
FL / Ind.EL.-W / SO / VO
S-Sn97Cu3S-SnAg4
S-Pb50Sn50
3
Ni + Ni-alloysIron materials
Common steels
AG 102 (L-Ag55Sn)AG 203 (L-Ag44)
AG 304 (L-Ag40Cd)
FH10 S-Pb50Sn50S-Sn96Ag4S-Sn97Cu3
3
CU 303 (L-CuZn40)CU 305 (L-CuNi10Zn42)
FH20Cobalt
CU 102 (L-Cu) -
FL / Ind / EL.-W. / AOSO / VO
S-Cd82Zn16Ag2 3
AG 403 (L-Ag56InNi) FH12 FL / Ind. / EL.-W.Cr- and Cr/Ni-steels
NI107/NI105/NI102AG 401/CU102
- SO / VO
S-Sn96Ag4 3
Noble metals AG 102 (L-Ag55Sn)AG 202 (L-Ag60)AG 401 (L-Ag72)Gold brazing alloys
FH10 FL / Ind.EL.-W.AO
SO / VO
S-Sn96Ag4 3
*) FL = Flame; EL.-W. = Electr. Res.; SO = Inert gas furnace; K = Copper-bit; Ind. = Induction; AO = Atmosphere furnacHL = Hot air jet
Table 4a
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
13/14
Principles of brazing technology
Umicore AG & Co. KG - BrazeTec, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-3107 Email: [email protected] Internet: www.Bra
Proposals (II) for brazing alloy (solder) / flux / brazing (soldering) technique combinations (for Group 2 and 3 baTable 3)
Base material Brazing alloy Flux Technique *) Solder Al and Al-alloys(with Mg and/or
Si contents 2%)
AL 104 (L-AlSi12) FL10 FLAO
S-Sn96Ag4S-Cd80Zn20
3
AG 301 (L-Ag50CdNi)AG 502 (L-Ag49), possibly
as layer brazing alloy
FH12
AG 502 (L-Ag49)CU 305 (L-CuNi10Zn42)
FH12FH21
Hard metals
Stellites
CU 102 (L-Cu), possiblywith tri-metal
-
FLInd.
SO / VO
-
-
Chromium,molybdenum,
AG 502 (L-Ag49) FH12
Tungsten, tantalum,niobium
Cu87MnCo 1) FH21
FL/Ind.
AO/SO
-
ZincAntimony
- - - S-Pb60Sn40S-Sn96Ag4
3
LeadBismuth
Tin
- - -S-Sn50Pb32Cd18 3
Titanium AG 401 (L-Ag72)PD 105
- SO (Argon)VO
-
ZirconiumBeryllium
PD 105 - SO (Argon)VO
-
GraphiteMetal oxide-
ceramics
AgCuTik 1) - SO (Argon)VO
-
*) FL = Flame; EL.-W. = Electr. Res.; SO = Inert gas furnace; K = Copper-bit; Ind. = Induction; AO = Atmosphere furnac
HL = Hot air jet1
) not laid down in standards
Table 4b
-
7/29/2019 En P 01 PrinciplesOfBrazingTechnology
14/14
Principles of brazing technology
BrazeTec GmbH, Rodenbacher Chaussee 4, D-63457 Hanau-WolfgangTelefon: +49 (0) 6181-59-03 Telefax: +49 (0) 6181-59-55 50 Email: [email protected] Internet: www.BrazeTec.de
The information given about our products,equipment, plants and processes is based onextensive research work and our technicalknowledge of applications. We provide thisinformation verbally and in writing according to thebest of our knowledge, but we do not accept anyresponsibility beyond that in the individual contract.We do however reserve the right to make technicalchanges as part of our product developmentactivities. Our technical service personnel areavailable on request to provide further advice andassistance to solve manufacturing and technicalproblems.
This does however not relinquish users of theirresponsibility to check our information andrecommendations prior to carrying out their ownwork. This is also true especially for deliveriesabroad with regard to the observance of protectionrights of third parties and with regard to applicationsand procedures not expressly given in writing by us.In the event of damage, our liability is limited tocompensation to the same degree as provided for inour General Terms and Conditions of Sale andDelivery for shortcomings in quality.