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1. Silver Brazed StainlessSteel Cable Presented by:
Erik Clark
Tim Flynn
Tony Foster
Peter Jones
Brian Martel
Ried Snyder
2. Stainless Steel Cable?
What is it?
Lets start with what a Cable is
3. Cable In this case it is a 1 x 19
cable that is made out of
little wires put together
To be exact it is 1 strand
of one set of 19 little wires
4. Cable Continued In this application it is important to use cable instead of a solid piece because cables are flexible and have give
Cable is cost effective
Cable is easy to form for this application
5. Stainless Steel
What is Stainless Steel?
Why would we want to use Stainless Steel?
6. Stainless Continued What is Stainless Steel?
Steel, Stainless High Alloy Steel (usually containing Cr, or Cr + Ni) designed for resistance to corrosion and/or oxidation
Chromium content in stainless varies from 13% - 27%
Many, but not all stainless alloys contain 8% - 10% Nickel
Here are some of the other metals used in stainless alloys;
Mn, Si, N, P, S, and or course, C
7. Stainless Continued Example of properties
Steel (18 CR - 8 Ni Stainless)
Modulus of elasticity E = 205,000MPa or 30x106psi
8. Stainless Continued Why would we want to use Stainless Steel?
Stainless Steel is needed to help avoid the problems created by corrosion
9. Stainless Continued Corrosion Control
The goal of using stainless steel is to control corrosion
There are different ways to do this
Protective coatings or
Avoidance of galvanic couples
10. Stainless Continued Protective coatings
This method works well for many applications
Cars, Houses, and other painted things
Galvanized Steel
Problems
Protective coatings can wear off leaving surface at risk
Coated materials must be treated with care
11. Stainless Continued One way to avoid galvanic couples is by limiting designs to a single type of metal.
Brass bolt – steel washer pitfall
This does not always solve the problem though
A cathode and anode may develop in a single material
12. Stainless Continued Alloying steel with certain other materials makes it resistant to the cathode anode relationship that creates corrosion
Stainless steel keeps the strength of regular steel without having the corrosion problem
13. Joining Stainless Steel Components Many Different Methods:
Welding
Brazing
Soldering
Adhesive Bonding
Mechanical Fastening
14. Brazing Outline Why Brazing?
Applications Involving Brazing
Brazing Processes
Filler Materials
15. The Method of Brazing Brazing employs filler metals having a liquidus above 450°C (840°F) and below the solidus of the metal.
In comparison:
Solders employ a filler metal which DOES melt below 450°C (840°F).
Welding applications end up melting a substantial amount of the base metal.
Adhesive bonding is becoming very competitive with other joining methods
16. Brazing Applications Brazing is often used to join stainless steels to dissimilar metals, such as carbon steels, low-alloy steels, and copper alloys.
Brazing can obtain strong, corrosion-resistant, leak-tight joints in small or thin walled components with minimal buckling and warpage.
Brazing can produce joints in delicate assemblies and in very thin-gage metals.
17. Brazeability of Stainless Steel No more difficult than carbon and low-alloy steels.
However, chromium oxide films which form during the brazing process must be adequately removed.
Their refractory and strongly adherent nature will prevent the molten metal from wetting the base metal.
18. Removing Chromium Oxides Many different techniques exist for removing chromium oxide:
Chemical cleaning @ room temperature
Heating to the brazing temperature in a hydrogen atmosphere
Coating the area with a chemically active flux which dissolves the oxide
Heating in a vacuum
Etc.
19. Brazing Processes Many different methods for brazing exist as well, including:
Furnace
Torch
Induction
Resistance
Salt-bathing
20. Furnace Brazing Popular because of its comparatively low equipment cost
Used extensively where the parts to be brazed can be assembled with the brazing material pre placed near or on the joint.
Heating is usually produced by electrical resistance.
21. Torch Brazing Commonly used for repairs, one-of-a-kind brazing jobs, and short production runs.
The technique is relatively simple and is similar to other torch welding applications.
Slightly reducing flames are commonly used to prevent oxidation.
Rather easily automated.
22. Brazing Filler Materials Silver (Ag)
Nickel (Ni)
Copper (Cu)
Gold (Au)
Which one used is based on mechanical properties, corrosion resistance, service temperature, compatibility with the base material, and cost.
23. Silver Brazing BAg – 3 is the most commonly used filler
Commonly applied with torch brazing, as opposed to furnace brazing.
Unable to be used for high-temperature applications -- below 370°C (700°F)
Many factors will vary heat temperature ranges used and time allowances.
24. Other Brazing Fillers Nickel is the second most common and allows for high corrosion resistance and high-temperature strength.
Copper has poor resistive properties and special protective atmospheres must be used during brazing.
Gold is high cost but can lead to some of the most corrosive resistant joinings.
25. Why Silver Brazing Then? Brazing is more applicable than welding since a minimum of the base material of the part will be lost.
Silver is cheaper and most widely used than other fillers, and special corrosion resistive properties are not needed.
Torch welding is easily applied and prevents the need for an automated furnace system.
26. Resources ASM Handbook Volume 6
ASM Specialty Handbook (Stainless Steels) Questions?