FROM WIKIPEDIA-----
Hard soldering" or "silver soldering" (performed with high-temperature solder containing up to 40% silver) is also often a form of brazing, since it involves filler materials with melting points in the vicinity of, or in excess of, 450 °C. Although the term "silver soldering" is used much more often than "silver brazing", it may be technically incorrect depending on the exact melting point of the filler in use. In silver soldering ("hard soldering"), the goal is generally to give a beautiful, structurally sound joint, especially in the field of jewelry. Thus, the temperatures involved, and the usual use of a torch rather than an iron, would seem to indicate that the process should be referred to as "brazing" rather than "soldering", but the endurance of the "soldering" apellation serves to indicate the arbitrary nature of the distinction (and the level of confusion) between the two processes.
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Brazing is a joining process whereby a non-ferrous filler metal or alloy is heated to melting temperature above 450°C (842°F), or, by the traditional definition that has been used in the United States, above 800°F (425)°C and distributed between two or more close-fitting parts by capillary action. At its liquid temperature, the molten filler metal and flux interacts with a thin layer of the base metal, cooling to form an exceptionally strong, sealed joint due to grain structure interaction. With certain metals, such as Nitinol (Nickel Titanium) and Niobium, a low temperature eutectic can form. This leads to the bonding of the two metals at a point that can be substantially lower than their respective melting temperatures. The brazed joint becomes a sandwich of different layers, each metallurgically linked to the adjacent layers. Common brazements are about 1/3 as strong as the materials they join because the metals partially dissolve each other at the interface and usually the grain structure and joint alloy is uncontrolled. To create high-strength brazes, sometimes a brazement can be annealed, or cooled at a controlled rate, so that the joint's grain structure and alloying is controlled. It is also at 1/3 strength because the metal used to braze is usually weaker than the substrate metal because it melts at a lower temperature, ensuring the substrate does not melt.
Braze welding
In another similar usage, brazing is the use of a bronze or brass filler rod coated with flux together with an oxyacetylene torch, to join pieces of steel. The American Welding Society prefers to use the term Braze Welding for this process, as capillary attraction is not involved, unlike the prior silver brazing example. Braze welding takes place at the melting temperature of the filler (e.g., 870 °C to 980 °C or 1600 °F to 1800 °F for bronze alloys) which is often considerably lower than the melting point of the base material (e.g., 1600 °C (2900 °F) for mild steel).
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Depending on what kind of work you plan on doing, you might consider investing in an O/A outfit and taking up Brazing first, before moving into Welding.
Brazing is an ART, done properly, the attached joints can be VERY strong, with little effect on the peices being worked on.
I like MIG welding too though, it has its place.
ARC welding is ALOT of fun, but takes patience and alot of practice. I learned on an old 220/ 3 phase outfit...We were welding 1" peices of steel together:chainsawguy:
TIG...Well, its expensive, takes alot of practice, but if you need a good clean, Slag free weld, especially on aluminum, THATS the way to go.
opcorn:
