Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from welding in that it does not involve melting the work pieces.
In short, welding is a technique that joins metals by melting the base metal and causing fusion, while brazing joins metals by melting and flowing a filler metal into the joint. In brazing and welding, fabricators add a filler metal into the joint. … In brazing, fabricators don’t melt the base metal.
Brazing is a process for joining two pieces of metal that involves the application of heat and the addition of a filler metal. This filler metal, which has a lower melting point than the metals to be joined, is either pre-placed or fed into the joint as the parts are heated.
Brazing soundly beats welding when joining dissimilar metals. As long as the filler material is metallurgically compatible with both base metals and melts at a lower temperature, brazing can create strong joints with barely any alteration of the base metals’ properties
Disadvantages of Brazing Include:
- Producing lower strength joints compared to welding.
- Producing joints that are not as well suited to high-temperature applications as welds.
- Fluxes may contain toxic components.
Brazing is performed at relatively low temperatures, reducing the possibility of warping, overheating or melting the metals being joined. It allows simple fit up and easy disassembly without the need for additional components like nuts, washers and O-rings.
The heat for brazing is typically provided by a hand-held torch, a furnace or an induction heating system. Other techniques include dip brazing and resistance brazing. Torch brazing is often used for small assemblies and low-volume applications.
A fluxing agent (or a controlled atmosphere as found in furnace brazing) is required for all brazing and soldering applications. The purpose of the flux is to remove oxides from the base material and to prevent oxidation during the heating process, thus promoting the free flow of the brazing filler metal.
These torches used for these applications are the air-natural gas and air-acetylene. Torches that provide excellent results on many brazing applications are oxygen with natural gas, or other gases such as propane or butane.
A “flux” in metallurgy (derived from the Latin word fluxus – meaning “flow”) is the agent used for cleaning, flowing, or purifying. Their function can vary but are an essential component in brazing. Essentially, fluxes remove oxides and other contaminants in order to create solid, high quality brazed joints.
Brazing, when performed correctly, is a joining process that produces a permanent bond between two or more materials by heating them to a temperature above 450°C (840°F), but lower than the melting-temperature of any of the materials being joined.
A brazing paste is a homogeneous mixture of the brazing filler metal powder (about 80-90wt. -%) and water or oil based flux-free binder. The binders are removed in the furnace during brazing.
Metal joining requires soldering, brazing, and welding. Each of these methods is different but has numerous things in common.
Cleaning – Most essential is the cleaning of metal pieces, whatever may be the process. Doing soldering, brazing, and welding on unclean metal pieces causes gas or liquid flow and structural defects.
Heated Material – All the three methods require heating either filler material, metal parts to be joined, or both. It requires sufficient heat to create a strong joint to serve the practical application.
Proper accessories – In brazing, soldering and welding operators require using safety gloves, protective clothes, helmets to save from a fire, projectiles slag, UV light. Operators need to cover skin, eyes, and very parts as safety measures.
Soldering :
The soldering process joins two metals together when solder applies to metal pipe sections. The solder, a filler metal, gets melted by soldering iron at a low temperature up to 450 degrees centigrade. The solder may be solid in wire form, paste form as flux, laid right over the materials to be joined. I do the heating here to solder only not the work pieces. The difference between soldering and brazing is the amount of heat involved only.
The most common use of soldering is electrical contacts mainly but applied in plumbing and metalwork of low temperatures. We apply the method for metal like iron, gold, silver, copper, and brass.
Brazing:
The brazing principle is the same as soldering where a combination of heat, filler material, and flux works to join the metals together. But in brazing, a flux solution between the filler metal and base metal is used to join in heating.
The difference between brazing and soldering is a temperature of 450 degrees centigrade used in brazing, which is much higher than soldering temperature. Unlike welding both soldering and brazing heat the filler metal sparing the base metal from melting and joins the two metals together.
Brazing is an adequate tool for very thin metal, like aluminum. Higher temperatures can damage these metals. It is also a handy tool for the joints, which are difficult to access on soldering. Most carbides, ferrous metals, and cermet can be fused by brazing.
Welding:
The high temperature heats the filler material and edges of the base metal to establish a strong weld between the workpieces of metals.
The temperature over 450 degrees centigrade involves welding which is much higher than soldering and brazing. Unlike in soldering and brazing, it melts the base metal to make a powerful bond.
Welding process used commonly in industries and day to day life. The applications include construction, building, automotive, shipbuilding, aircraft, pipelines, tanks, vessels, heavy construction equipment, erecting bridges, and railroads. In one procedure, it uses thousands of welding joints.
There are several methods of welding such as TIG welding, MIG welding, Arc/stick welding, Gas welding, Laser welding, and underwater welding in marine applications.
The brazing if done properly can be stronger than the pieces to be joined, but not as strong as the welding joint. Brazing does not affect the base metals. Soldering is the lowest temperature technique to fuse the materials. The soldering can be done with metals like silver, gold, brass. and iron.
Proper soldered and brazed joints can be stronger than the base metal pieces, but are not as strong welded joints. Soldering is low-temperature analog to brazing but not strong as welding.
The difference between welding and brazing is that welding can change the base metal structure and its composition while brazing does not affect the base material. The properly completed brazing offers a strong joint as welding does. Brazing is quite a handy tool for thin metal structure.
