sec11 silverbrazing web

7/31/2019 Sec11 SilverBrazing Web

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W e l d i n g C o n s u m

a b l e s

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Product Reerence Manual - Sect ion 11 - Welding Consumables - Silver Brazing Alloys

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a b l e sSilver Brazing Alloys

Fundamentals o Gas Welding & Brazing 2

Uncoated Cadmium-Free Silver Brazing Alloys 6

Flux Coated Cadmium-Free Silver Brazing Alloys 7

Silver Brazing Flux 8




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Welding TechniqueSuccessul welding depends on the ollowing actors:

1. Selection o the correct consumables

2. Selection o the correct ame setting

3. Selection o the correct application techniquesa) Correct angle o rod to work b) Correct travel speed

4. Selection o the welding preparation

Silver Brazing

Choice o Filler Metal

An alloy is normally selected or its melting and owcharacteristics.

The easiest to use fller materials are the high silver, ree-owing alloys, because o their low melting temperatures andnarrow melting ranges. The higher the brazing temperatureand the wider the melting range o the alloy, the moredifcult the brazing operation will be.

Pre-Cleaning

It is important that the mating suraces o the componentsto be brazed are ree rom oil, grease and any surace oxidelayer prior to joining. Most engineering components requirenothing more than degreasing beore assembly.

Oxide removal can be accomplished either chemically ormechanically. Mechanical removal is preerable, because thesurace is roughened and excellent bonding is obtained. Amedium emery cloth provides about the right amount o surace roughness.

Oil and grease removal is best carried out by using a solventdegreasing agent, but hot, soapy water is better than nothingat all.

Fluxing

The choice o the correct ux is just as important as thechoice o fller material. There are three desirable propertieso a ux:

1. The ux must melt and become active below the meltingpoint o the brazing alloy. Borax or borax based uxes arenot sufciently molten at the low temperatures at whichsilver brazing alloys are used. A low temperature uoridebased ux such as Easyo needs to be employed.

2. The lux must be capable o removing the oxides oundon the parent materials. Easylo lux will remove theoxides ound on most common engineering materials

such as mild steel, brass and copper. Special luxes maybe required on certain types o highly alloyed steel andtungsten carbide tool tips. It is also necessary to use aspecially ormulated lux on aluminium bronze oraluminium brasses containing more than 2% aluminium.

3. The lux must remain active at the brazing temperatureor long enough to allow the brazing operation to becarried out. Fluxes are chemical compounds whichdissolve oxides ormed in heating. Like most chemicalcompounds, a lux eventually reaches the point whereit is saturated and becomes unable to dissolve any moreoxide. I the lux residues appear blackened and glassy,the lux has most likely been exhausted during heating,and a lux with higher time / temperature stability shouldbe used.

For most engineering requirements, there are two uxesthat will take care o most needs. These are Easyo ux andTenacity No. 5 ux paste.

Easyo Flux

This is the accepted general-purpose ux or use with alllow-temperature silver brazing alloys that have brazingtemperatures not exceeding 800°C. It will successullyux all the common engineering materials, and its residuesare soluble in hot water. Where difculty is encounteredwhen removing residues, immersion in 10% caustic soda issuggested.

Tenacity No. 5

This is a higher temperature ux, suitable or use with alloyswith brazing temperatures not exceeding 900ºC or where

long heating times are involved. In common with Easyo ux,it will deal with all common engineering materials and maybe used on stainless steels. Tenacity No. 5 residues cannot beremoved in hot water, and are best removed mechanically orby the use o 10% sulphuric acid.

Flux Application

The best way to apply a ux is to paint it onto the joint as apaste beore assembly. It is common to see operators heatingthe rod end and dipping it into the ux, and then applyingboth to the joint. This ‘hot rodding’ technique has thedisadvantages that the ux does not protect the joint duringthe heating cycle and that the limited amount o ux applied

does not allow alloy penetration into the capillary gap.

I a ux powder is used, it should be mixed to a double creamconsistency with water and a ew drops o detergent. Itshould also be applied to the joint by means o a paint brush.Too much ux will rarely result in a bad joint, but too littleux will invariably give joints o poor quality.

Heating the Joint and Applying the Alloy

When heating a joint or brazing, it is essential that it is slowlyand evenly heated to the brazing temperature.

The type and size o ame used will depend on the parentmaterials and the mass o the components. Oxy/acetylene,air/acetylene and air/propane are commonly used, but careshould be taken with the frst due to the high ame intensity,which may melt the parent materials.

Fundamentals o Gas Welding & Brazing

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I the mass o metal is very large, more than one torch shouldbe used to raise the components to temperature beore theux becomes exhausted.

As a temperature guide, either the colour o the metals or thecondition o the ux may be used. The ux on a joint that hasreached the correct temperature or brazing should be clear,

uid and ow over the joint area like water.

When the brazing temperature is reached, the fller metal isapplied by touching the joint gap with the rod and applyingsome indirect or splash heat rom the torch to the parentmaterial. The molten fller metal will ollow the heat rom theame as it is directed along the joint. The brazing alloy shouldbe applied according to its ow characteristics; an alloy withree-owing characteristics should be touched at one pointon the joint, rom where it will ow into and around the jointby capillary action. A less ree-owing alloy should be appliedalong or around the entire joint, building up a fllet o alloy.

I phosphorous bearing fller rods are used, such as Eesibraze2, the colour o the metal should be a dull cherry red beorethe rod is applied to the joint gap.

Once brazing has been completed, the heating should bediscontinued, as excess heating may cause metallurgicalproblems with the parent materials and porosity in the fllermaterials.

When the alloy has solidifed, the joint can be quenched inwater to help remove ux residues.

Quenching should only be carried out when it will notdamage the properties o the parent metals, or cause crackingbecause o stresses caused by the thermal shock (e.g. in thecase o tungsten carbide pieces).

Removal o Flux Residues

The method o residue removal depends on the type o uxthat has been used. Easyo ux residues can be quite simplyremoved by soaking in hot water, provided they are not ina burnt and blackened condition. Complete ux residueremoval is usually possible within 10–15 minutes o soakingin water with a temperature o 60°C or above. Ater soaking,the joints should be scrubbed under running water to ensurecomplete cleanliness.

Tenacity No.5 ux residues are not water soluble and are bestremoved by some mechanical means (e.g. shot blasting).

Acid pickling is not eective in removing ux unless theresidues are in a burnt and blackened condition. I picklingis necessary, it should be carried out ater the ux residueremoval operation.

Health and Saety

Brazing alloys and uxes contain elements which, i overheated,produce umes that may be harmul or dangerous to health.Brazing should be carried out in a well ventilated area withoperators positioned so that any ume generated will notbe inhaled. Adequate ventilation to prevent an accumulationo umes and gases should be used. Where ume levelscannot be controlled below the recognised exposure limits,

use a local exhaust to reduce umes and gases. In confnedspaces without adequate ventilation, an air-ed breathingsystem should be used. When outdoors, a respirator may berequired. Precautions or working in confned spaces shouldbe observed.

Apart rom ume hazards, ux can be irritating to the skin andprolonged contact should be avoided.

Beore use, read all the manuacturer’s instructions and reerto the warning labels on the packaging, and ask your employeror the Materials Saety Data Sheet (MSDS). You can obtainthe MSDS by reerring to our website at www.arox.com or

by calling 0860 020202.

Joint Design

The best brazed joints are those which have a capillary jointgap into which the molten fller metal can ow. A comparisono the dierent joint designs used in welding and brazing isshown below.

The most common type o joint used or brazing is the lap joint, or the sleeve joint in the case o tubular components.To design a good lap joint, two criteria should be considered:

1. The joint gap

2. The degree o overlap

It is these two parameters that determine the ultimate jointstrength, rather than the properties o the fller metal.

A correctly designed brazed joint will oten be stronger thanthe parent materials rom which it is constructed.




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The best degree o overlap or a brazed joint is 3–4 t where tis the thickness o the thinnest parent metal part that makesup the joint.

The general rule or tubular parts is that the overlap shouldbe one pipe diameter or sizes up to 25 mm diameter tube.

The most suitable joint gap depends mainly on the owcharacteristics o the fller metal. The joint gaps or the variousalloys listed in the ollowing section have been indicated. Thegaps quoted are those that should be present at the brazingtemperature, the cold clearances being adjusted as necessaryto account or any dierence in the expansion properties o the parent materials.

Gas Welding

Welding Techniques

The heat generated by an oxy-uel ame is used to melt theparent metal in the joint orming a weld pool. I a fller rodis to be used, it must also be melted into the weld pool. Theame envelope also protects the molten weld pool and theend o the fller rod rom the atmospheric contamination.

The weld is continuous and progresses at the speed at whichthe parent and fller materials can be melted to orm theweld pool, but ast enough not to allow the weld pool toburn through the component creating a hole.

The fller rod, i used, is constantly ed into the weld poolat the rate required to give the correct bead width, deptho penetration and reinorcement height or the application.The length o the weld will dictate how much fller rod isrequired. Usually more than one length o rod will be needed

and, when a new length o rod is needed, a stop and re-startwill have to be eected. Stop-start can aect the quality o the weld i care is not taken to ensure the weld pool is reeo contamination and enough time is given to allow the weldpool to become ully molten.

There are three recognised gas welding techniques used.These are:

• Leftwardwelding

• Rightwardwelding

• Allpositionrightwardwelding.

Letward Welding (or Forward Welding)

Letward welding is the most common technique used ingas welding. In this technique, the ame ollows the fller rodalong the joint o the weld and, with the torch in the righthand, the movement is rom right to let or rom let to righti the torch is held in the let hand.

Letward Welding Technique

30–40° 40–50°

This technique can be used in all welding positions. Themethod is the same, with the ame ollowing the fller rod,irrespective o the welding position.

Rightward Welding (or Backhand or Backward

Welding)

With this technique, the fller rod ollows the ame alongthe joint o the weld. With the torch in the right hand, themovement is rom let to right and the opposite when thetorch is in the let hand. Rightward welding is limited in itsuses and is only used in the at (1G, PA) position and ormaterial thicknesses between 4-16 mm thick. When weldingbutt joints o between 4-6 mm, no edge preparation isrequired. For thicker materials up to 16 mm, edge preparationwill be required. However, it is possible to complete this jointin one pass.

Rightward Welding Technique

30–40°40–50°

All-Position Rightward Welding (APR)

With this technique, the wire can ollow, precede or be inline with the ame, depending on the welding position used.The all-position rightward technique is or welding thickermaterials in the vertical-up, vertical-down, horizontal-verticaland the overhead positions.




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a b l e s

All-Position Rightward Welding Technique

45–60°

The technique is mainly used or gas welding pipe o alldiameters and wall thicknesses up to 6 mm in a single pass,with no edge preparation to the material. This technique wasdeveloped to compete with manual metal arc welding andis used mainly on construction sites or welding heating andventilating pipe-work.

Warning

Brazing can give rise to excessive noise, eye and skin burnsdue to the ame and its radiation, and can be a potentialhealth hazard i you breathe in the emitted umes and gases.

Brazing should be carried out in a well ventilated area, with

operators positioned so that any ume generated will notbe inhaled. Adequate ventilation to prevent an accumulationo umes and gases should be used. Where ume levelscannot be controlled below the recognised exposure limits,use a local exhaust to reduce umes and gases. In confnedspaces without adequate ventilation, an air-ed breathingsystem should be used. When outdoors, a respirator may berequired. Precautions or working in confned spaces shouldbe observed.

Apart rom ume hazards, ux can be irritating to the skin andprolonged contact should be avoided.

Beore use, read all the manuacturer’s instructions and reer

to the warning labels on the packaging, and ask your employeror the Materials Saety Data Sheet (MSDS). You can obtainthe MSDS by reerring to our website at www.arox.com orby calling 0860 020202.




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P r o d u c t

N a m e

I t e m

N u m b e r

D i a m e t e r

( m m )

P a c k

S i z e

A p p l i c a t i o n

C l a s s i f c a t i o n

C h e m i s t r

y ( % )

M e l t i n g

R a n g e

( º C )

T e n s i l e

S t r e n g t h

O p t i m u m J o i n t

G a p ( m m )

A g

C u

Z n

S

n

S i

N i

S i l v e r f o 5 5

W 0 0 1 0 5 5

1 , 5

1 0 0 g

T h e S i l v e r l o r a n g e o c a d m i u m - r e e

a l l o y s r e p r e s e n t s t h e u l t i m a t e s a e t y

p r e c a u t i o n s a g a i n s t c a d m i u m u m e .

C a d m i u m c o n t e n t i s c o n t r o l l e d t o

0 , 0 2 5 % m a x . a n d t h e u s e o t h e s e a l l o y s

i s h i g h l y r e c o m m e n d e d - o r s o m e

a p p l i c a t i o n s i t i s o b l i g a t o r y , e . g . o o d

h a n d l i n g e q u i p m e n t .

S i l v e r l o 5 5 i s t h e l o w e s t m e l t i n g p o i n t

a l l o y i n t h e g r o u p a n d h a s b e e n w i d e l y

a d o p t e d a s a s u b s t i t u t e o r E a s i l o 1 a n d

E a s i l o 2 .

S i l v e r l o 4 0 i s a g e n e r a l p u r p o s e a l l o y

s u i t a b l e o r u s e o n m o s t e n g i n e e r i n g

m a t e r i a l s .

S i l v e r l o 3 0 i s a n e c o n o m i c a l l o y m a i n l y

u s e d t o b r a z e c o p p e r a n d m i l d s t e e l .

A l l o y s w i t h l e s s t h a n 2 5 % s i l v e r a r e

w i d e l y u s e d o n c o p p e r a n d s t e e l . T h e y

g i v e a g o o d c o l o u r m a t c h o n b r a s s b u t

r e q u i r e c l o s e t e m p e r a t u r e c o n t r o l d u e

t o t h e i r h i g h m e t i n g p o i n t s . D u e t o t h e

i r

r e l a t i v e l y s h o r t m e l t i n g r a n g e , t h e s e

a l l o y s a r e s u i t a b l e o r s t e p b r a z i n g .

F r i d g e b r a z e w a s s p e c i a l l y d e v e l o p e d t o

o v e r c o m e l i q u i d e m b r i t t l e m e n t w h e n

b r a z i n g g a l v a n i z e d s t e e l p i p e s u s e d i n

t h e r e r i g e r a t i o n i n d u s t r y .

D I N L - A g 5 5 n

B S A G 1 4

5 5

2 1

2 2 2

-

-

6 3 0 - 6 6 0 3 9 0 M P a

0 , 0 5 - 0 , 1 5

W 0 0 1 0 5 6

1 , 5

1 k g

W 0 0 1 0 5 7

1 , 5

5 k g

W 0 0 1 0 5 8

3 , 0

1 k g

S i l v e r f o 4 0

W 0 0 1 1 7 0

1 , 5

1 0 0 g

B S A G 2 0

4 0

3 0

2 8 2

-

-

6 5 0 - 7 1 0 4 5 0 M P a

0 , 0 7 5 - 0 , 2 0

W 0 0 1 1 7 1

3 , 0

1 0 0 g

W 0 0 1 1 7 2

3 , 0

1 k g

S i l v e r f o 3 0

W 0 0 1 0 3 0

1 , 5

1 0 0 g

B S A G 1 6

3 0

3 8

3 2 -

-

-

6 9 5 - 7 7 0 5 0 5 M P a

0 , 0 7 5 - 0 , 2 0

F r i d g e b r a z e

B a r e W 0 0 1 5 5 9

1 , 5

1 0 0 g

-

2 5

4 0

3 4 -

-

1 , 5

6 7 0 - 7 3 0 4 7 0 M P a

0 , 0 7 5 - 0 , 2 0

W 0 0 1 5 6 0

1 , 5

1 k g

W 0 0 1 5 6 1

1 , 5

2 k g

U n c o

a t e d C a d m i u

m - F r e e S i l v e r B r a z i n g A l l o y s

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a b l e s

P r o d u c t

N a m e

I t e m

N u m b e r

D i a m e t e r

( m m )

P a c k

S i z e

A p p l i c a t i o n

C

l a s s i f c a t i o n

C o l o u r

C o d e

C h e m i s t r y ( % )

M e l t i n g

R a n g e

( º C )

T e n s i l e

S t r e n g t h

O p t i m u m J o i n t

G a p ( m m )

A g

C u

Z n

S n

S i

N i

F l u x c o a t 4 0 2

W 0 0 1 1 9 7

1 , 5

1 0 0 g

T h e S i l v e r c o a t a n d F l u x c o a t r a n g e

o

c a d m i u m - r e e l u x c o a t e d a l l o y s

r e

p r e s e n t s t h e u l t i m a t e s a e t y

p r

e c a u t i o n s a g a i n s t c a d m i u m u m e .

C a d m i u m c o n t e n t i s c o n t r o l l e d t o

0 , 0 2 5 % m a x . a n d t h e u s e o t h e s e

a l l o y s i s h i g h l y r e c o m m e n d e d - o r

s o

m e a p p l i c a t i o n s i t i s o b l i g a t o r y , e . g .

o o d h a n d l i n g e q u i p m e n t .

F l u x c o a t 4 0 2 i s a g e n e r a l p u r p o s e a l l o y

s u

i t a b l e o r u s e o n m o s t e n g i n e e r i n g

m a t e r i a l s .

S i l v e r c o a t 3 0 i s a n e c o n o m i c

a l l o y m a i n l y u s e d t o b r a z e

c o

p p e r a n d m i l d s t e e l .

A l l o y s w i t h l e s s t h a n 2 5 % s i l v e r a r e

w i d e l y u s e d o n c o p p e r a n d s t e e l . T h e y

g i v e a g o o d c o l o u r m a t c h o n b r a s s

b u

t r e q u i r e c l o s e t e m p e r a t u r e c o n t r o l

d u

e t o t h e i r h i g h m e l t i n g p o i n t s .

F r

i d g e b r a z e w a s s p e c i a l l y d e v e l o p e d t o

o v

e r c o m e l i q u i d e m b r i t t l e m e n t w h e n

b r

a z i n g g a l v a n i z e d s t e e l p i p e s u s e d i n

t h e r e r i g e r a t i o n i n d u s t r y .

B S A G 2 0

Y e l l o w

4 0

3 0

2 8

2

-

-

6 5 0 - 7 1 0

4 5 0 M P a

0 , 0 7 5 - 0 , 2

W 0 0 1 1 8 0

1 , 5

S l e e v e

S i l v e r c o a t 3 0

W 0 0 1 0 3 1

1 , 5

1 0 0 g

-

L i g h t

Y e l l o w

3 0

3 8

3 2

-

-

-

6 9 5 - 7 7 0

5 0 5 M P a

0 , 0 7 5 - 0 , 2

W 0 0 1 0 3 2

1 , 5

1 k g

F u x C o a t e d

F r i d g e b r a z e

W 0 0 1 5 5 6

1 , 5

1 0 0 g

-

P u r p l e

2 5

4 0

3 4

-

-

1 , 5

6 7 0 - 7 3 0

4 7 0 M P a

0 , 0 7 5 - 0 , 2

W 0 0 1 5 5 7

1 , 5

1 k g

W 0 0 1 5 5 8

1 , 5

2 k g

S i l v e r c o a t 1 8

W 0 0 1 0 1 8

1 , 5

1 0 0 g

-

B l u e

1 8

4 6

3 6

0 , 3

-

-

7 8 5 - 8 1 5

4 7 0 M P a

0 , 0 7 5 - 0 , 2

W 0 0 1 0 1 9

1 , 5

1 k g

F l u x C o a t e d C a d m

i u m - F r e e S i l v e r B r a z i n g A l l o y s

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Product ItemNumber

WorkingRange (ºC)

ClassifcationDIN 8511

FluxForm

Pack Size Characteristics ResidueRemoval

Easyo Flux W001852

W011854

550 - 800 F-SH1 Powder 250 g jar

5 kg container

-

-

-

-

Easyo Flux Paste W001836 500 - 825

001 - 862

F-SH1 Paste 500 g jar

1 kg container

-

-

-

-

Tenacity No. 5

Flux Paste

Stainless Steel

Grade

W001865 600 - 900 F-SH1/2 Powder - - -

Silver Brazing Flux

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