Silver-flo™ Filler Metals


Silver-flo™ products can be used to join the common engineering metals such as copper, copper alloys (brass, bronze, nickel silver, aluminium bronze, copper nickel), nickel alloys, steel, stainless steel and tungsten carbide.

Silver-flo™ 55 and 56 are general-purpose cadmium-free filler metals combining low brazing temperatures with short melting ranges. Both are free flowing, produce neat joints and are easy to use. They are used as replacements for cadmium-containing filler metals. Silver-flo™ 40 is a popular general-purpose product with medium melt and flow characteristics. Silver-flo™ 302 is a higher- and longer-melting filler metal and a useful gap-filling alloy.

Standard Filler Metals

Silver-flo™ 55
Ag
55
Cu
21
Zn
22
Sn
2
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 155
 Melting Range
 630 - 660°C
Silver-flo™ 55 is an easy to use, general purpose silver brazing filler metal. It has a low brazing temperature, short melting range and is free flowing when molten, producing neat joints with small fillets.
Silver-flo™ 55 is a cadmium-free replacement for the high silver (38-50%) cadmium containing filler metals. It can be used on most common engineering metals.EN1044:1999
AG103

Silver-flo™ 56
Ag
56
Cu
22
Zn
17
Sn
5
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 156
 Melting Range
 618 - 652°C
Silver-flo™ 56 has very similar properties to Silver-flo™ 55. It has a low brazing temperature, short melting range and is free flowing when molten, producing neat joints with small fillets. Originally conforming to the US standard AWS A5.8 BAg-7, it can be used as a cadmium-free replacement for the high silver (38-50%) cadmium containing filler metals.
AMS/AWS A5.8
AMS 4763, AWS Bag-7

EN1044:1999
AG102

Silver-flo™ 452
Ag
45
Cu
27
Zn
25.5
Sn
2.5
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 145
 Melting Range
 640 - 680°C
Silver-flo™ 452 is a general purpose filler metal with 45% silver bridging the gap in properties and cost between high silver 55/56% filler metals and the medium silver 38/40% filler metals. It has the lowest silver content to braze PCD segments below 750˚C without degrading the diamond layer. It has good flow properties, but a slightly higher brazing temperature than the high silver content filler metals.
EN1044:1999
AG104

Silver-flo™ 40
Ag
40
Cu
30
Zn
28
Sn
2
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 140
 Melting Range
 650 - 710°C
Silver-flo™ 40 offers a good combination of properties. It has a medium brazing temperature, melting range, flow characteristics and silver content. Silver-flo™ 40 is widely used as a general purpose silver brazing filler metal as well as for joining copper and its alloys to steel in HVAC&R applications. AMS/AWS A5.8
BAg-28

EN1044:1999
AG105

Silver-flo™ 38
Ag
38
Cu
31
Zn
29
Sn
2
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 138
 Melting Range
 660 - 720°C
Silver-flo™ 38 has similar properties to Silver-flo™ 40. It has a medium brazing temperature, melting range, flow characteristics and silver content. Silver-flo™ 38 is favoured in different global regions to Silver-flo™ 40 where it is also used in general purpose and HVAC&R applications.
Silver-flo™ 302
Ag
30
Cu
36
Zn
32
Sn
2
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 130
 Melting Range
 665 - 755°C
Silver-flo™ 302 has a long melting range and poor flow characteristics, which make it an ideal choice for applications where fillet build ups are required or close tolerance joint gaps are not present. It is used for brazing steel, copper and copper alloy tubes and fittings in HVAC&R and automotive applications. It is a popular choice as a flux coated rod for site work.
EN1044:1999
AG107

Silver-flo™ 252
Ag
25
Cu
40
Zn
33
Sn
2
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 125
 Melting Range
 680 - 760°C
Silver-flo™ 252 has a long melting range and poor flow characteristics, which make it an ideal choice for applications where fillet build ups are required or close tolerance joint gaps are not present. Like Silver-flo™ 302 it may be used for brazing steel, copper and copper alloy tubes and fittings in HVAC&R and automotive applications.
EN1044:1999
AG108

Filler Metals for Special Applications

Silver-flo™ 60
Ag
60
Cu
26
Zn
14
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 695 - 730°C
Silver-flo™ 60 is a filler metal specified for use on copper nickel and nickel alloys (in particular 70:30 copper nickel). It has a brazing temperature above the stress relieving temperature of many of these types of metals thus preventing liquid metal stress cracking as a result of inter-granular penetration. It is resistant to dezincification.
Silver-flo™ 56S
Ag
56
Cu
22
Zn
16.75
Sn
5
Si
0.25
 
 
 
 
 
 
 -
 -
 Melting Range
 618 - 652°C
Silver-flo™ 56S is a Johnson Matthey proprietary filler metal which has a small addition of silicon, is very free flowing and produces smooth neat joints with small fillets. It is not recommended on carbon steel components that are subject to high impact or fatigue stress in service.
Silver-flo™ 453S
Ag
45
Cu
25
Zn
26.8
Sn
3
Si
0.2
 
 
 
 
 
 
 -
 -
 Melting Range
 640 - 680°C
Silver-flo™ 453S has a small addition of silicon and produces smooth neat joints with small fillets making it popular for hand torch brazing of decorative brass components. Like other high silver content silicon containing filler metals it is not recommended for use on carbon steel components that are subject to high impact or fatigue stress in service.
Silver-flo™ 44
Ag
44
Cu
30
Zn
26
 
 
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 244
 Melting Range
 675 - 735°C
Silver-flo™ 44 has a medium brazing temperature, melting range, flow and silver content. Although it is not preferred to the more common Silver-flo™ 40 or 38 it has found use in marine applications because it is resistant to dezincification. It is also used as a medium temperature filler metal for copper alloy tubes where joint gaps are variable and a fillet is desirable.
EN1044:1999
AG203

Silver-flo™ 43
Ag
43
Cu
37
Zn
20
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 690 - 775°C
Silver-flo™ 43 has a medium brazing temperature, long melting range, and poor flow characteristics. It is not commonly used but has found use in the shipbuilding industry and in marine applications because it is the lowest silver content filler metal, which is resistant to dezincification. It is a good fillet forming and gap filling filler metal.
Silver-flo™ 24
Ag
24
Cu
43
Zn
33
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 740 - 800°C
Silver-flo™ 24 has been incorporated into aviation / aerospace industry standards and is consequently used in the manufacture of components for applications in this field. It is also used as the first alloy in a two-step silver brazing operation, where the second joint is made with Silver-flo™ 55.
Silver-flo™ 20
Ag
20
Cu
44
Zn
35.85
Si
0.15
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 776 - 815°C
Silver-flo™ 20 is a high melting point silver brazing filler metal that has a comparatively narrow melting range providing reasonable flow properties when molten. It can be used when colour matching to brass is required.

Less Common / Reference Filler Metals

Silver-flo™ 45
Ag
45
Cu
25
Zn
30
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 680 - 700°C
Silver-flo™ 45 is a cadmium free silver brazing alloy originally developed and manufactured to a Johnson Matthey specification. Today this alloy has been largely superseded by Silver-flo™ 452, and is generally only offered where it is included in an old specification.
Silver-flo™ 45 combines a low brazing temperature with a short melting range. It is very free flowing and produces smooth neat joints with small fillets. The alloy is tin and silicon free. The optimum joint gap at brazing temperature is normally 0.05-0.15mm.
Silver-flo™ 34
Ag
34
Cu
36
Zn
27.5
Sn
2.5
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 134
 Melting Range
 630 - 730°C
Silver-flo™ 34 is a cadmium free silver brazing filler metal. It exhibits poor / sluggish flow characteristics melting over a 100°C temperature range. Because of these characteristics Silver-flo™ 34 is not widely used today.
Silver-flo™ 34 has an ability to fill gaps that cannot be tightly controlled and to build fillets. Optimum joint gaps at brazing temperature are 0.075-0.2mm.
EN1044:1999
AG106

Silver-flo™ 33
Ag
33
Cu
33.5
Zn
33.5
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 700 - 740°C
Silver-flo™ 33 is a cadmium free silver brazing filler metal. It shows free flowing characteristics melting over a short, but comparatively high, temperature range (700-740°C). It is a good brazing filler metal that has been used as the second filler metal in a three step sequential brazing process along with Silver-flo™ 16 and Silver-flo™ 55.
Silver-flo™ 33 is not widely used today. Optimum joint gaps at brazing temperature are 0.075-0.2mm.
Silver-flo™ 30
Ag
30
Cu
38
Zn
32
 
 
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 230
 Melting Range
 695 - 770°C
Silver-flo™ 30 is a cadmium free silver brazing filler metal that has been adopted for a thermal spray coating process used in the aerospace industry. It is supplied as a wire on plastic reels suitable for feeding into a thermal spray gun.
The filler metal itself has a long and high melting range and poor flow characteristics hence it is not used as a brazing filler metal to any extent. Optimum joint gaps at brazing temperature are 0.075-0.2mm.
EN1044:1999
AG204

Silver-flo™ 25
Ag
25
Cu
40
Zn
35
 
 
 
 
 
 
 
 
 
 
 ISO 17672
 Ag 225
 Melting Range
 700 - 790°C
Silver-flo™ 25 is a high melting point cadmium free silver brazing filler metal. It has a high melting temperature(700 to 790°C) with a quoted melting range of 90°C. This melting range suggests medium to sluggish flow properties when molten. The high brazing temperature of the filler metal makes it less easy to use than the high silver content alloys.
Optimum joint gaps at brazing temperature are 0.075-0.2mm.
EN1044:1999
AG205

Silver-flo™ 18
Ag
18
Cu
45.75
Zn
36
Si
0.25
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 784 - 816°C
Silver-flo™ 18 is a high melting point cadmium free silver brazing filler metal. It has a high melting temperature(784 to 816°C) but a narrow melting range of only 32°C providing good flow properties when molten. The high brazing temperature of the filler metal makes it less easy to use than the high silver content alloys. Consequently it is not widely used. This product is a relatively inexpensive filler metal to purchase. However the cost per brazed joint of actually using the alloy may not be favourable in comparison to lower melting point, higher silver content filler metals. Optimum joint gaps at brazing temperature are 0.075-0.2mm.
Silver-flo™ 16
Ag
16
Cu
50
Zn
34
 
 
 
 
 
 
 
 
 
 
 -
 -
 Melting Range
 790 - 830°C
Silver-flo™ 16 is a high melting point cadmium free silver brazing filler metal. It has a high melting temperature(790 to 830°C) but a narrow melting range of only 40°C providing good flow properties when molten.The high brazing temperature of the filler metal makes it less easy to use than the high silver content alloys. Consequently it is not widely used. This product is a relatively inexpensive filler metal to purchase. However the cost per brazed joint of actually using the alloy may not be favourable in comparison to lower melting point, higher silver content filler metals. Optimum joint gaps at brazing temperature are 0.075-0.2mm.

 
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