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Glossary

A

AGGRESSION/EROSION – Excessive alloyinc can lead to catastrophic effects during brazing. It is primarily a function of time and temperature. Surface dissolution and inter-granular attack are manifestations.

ALLOYING – An interaction between the base metal and filler metal where a minimal dilution of each occurs. This is identified by a migration of elements across the joint interface. Alloying, on a limited scale, is generally beneficial- often increasing joint strength above that obtained by simple wetting. However, it can be based upon chemical compositions, affect corrosion resistance.

ARC BRAZING (AB) – A brazing process in which the heat required is obtained from an electric arc.

AS-BRAZED – The condition of brazements after brazing and prior to any subsequent thermal, mechanical or chemical treatments.

AUTOMATIC BRAZING – Brazing with equipment which performs that brazing operation without constant observation and adjustment by a brazing operator. The equipment may or may not perform the loading and unloading of the work. See machine brazing.

B

BASE MATERIAL – The material to be welded, brazed, soldered or cut. See also base metal and substrate.

BASE METAL – The metal to be welded, brazed or soldered or cut. The use of this term implies that materials other than metals are also referred to, where this is appropriate. See also base material and substrate.

BASE METAL TEST SPECIMENS – A test specimen composed wholly of base metal.

BINDER – A liquid material used in the supplication of powders that cause the powder to compact and stay in place, even after the binder is removed during brazing.

BLIND JOINT- A joint where no part of it is visible to view.

BLOCK BRAZING (BB) – A brazing process in which the heat required is obtained from heated blocks applied to the parts to be joined.

BOND – A unifying force that holds things together.

BRAZE – A bond produced by heating an assembly to suitable temperatures and by using a filler metal having a liquidus above 450 C (840 F) and below the solidus of the base metal. The filler metal is distributed between the closely fitted faying surfaces of the joint by capillary action.

BRAZE WELDING – A welding process variation in which a filler metal, having a liquidus above 450 C (840 F) and below the solidus of the base metal, is used. Unlike brazing, the filler metal is not distributed in the joint by capillary action.

BRAZEABILITY – The capacity of a metal to be brazed under the fabrication conditions imposed into a specific suitably designed structure and to perform satisfactorily in the intended service.

BRAZEMENT – An assembly having component parts joined by brazing.

BRAZER – One who performs a manual or semi-automatic operation

BRAZING – A group of welding processes which produces coalescence of materials by heating them to a suitable temperature and by using a filler metal having a liquidus above 450 C (840 F) and below the solidus of the base metal. The filler metal is distributed between the closely fitted laying surfaces of the joint by capillary action.

BRAZING ALLOY – See preferred term brazing filler metal.

BRAZING FILLER METAL – The metal which fills the capillary gap and has a liquidus above 450 C (840 F) but below the solidus of the base materials.

BRAZING OPERATOR – One who operates machine or automatic brazing equipment.

BRAZING PROCEDURE – The detailed methods and practices including all joint braze procedures involved in the production of a brazement. See joint brazing procedure.

BRAZING SHEET – Brazing filler metal in sheet form, which can be with or without a binder.

BRAZING TECHNIQUE – The details of a brazing operation which, within the limitations of the prescribed brazing procedure, are controlled by the brazer or the brazing operator.

BRAZING TEMPERATURE – The temperature to which the base metal is heated to enable the filler metal to wet the base metal and for a brazed joint.

BRAZING TEMPERATURE RANGE – The temperature range within which brazing can be conducted.

C

CAPILLARY ACTION – The force by which liquid, in contact with a solid, is distributed between closely fitting facing surfaces of the joint to be brazed or soldered.

CEMENT – A viscous liquid, either a rubber or acrylic base, which acts as both a vehicle and binder. It is mixed with any powdered filler metal to permit application with a brush, eyedropper, etc. It causes the metal to compact, holding it in place, even after it volatilizes.

CLAD BRAZING – A metal sheet on which one or both sited are clad (coated) with brazing filler metal. Clad brazing is found most often in aluminum brazing.

COPPER BRAZING – A term improperly used to denote brazing with copper filler metal. See preferred terms furnace brazing and braze welding.

CORROSIVE FLUX – A flux with residue that chemically attack the base metal. It may be composed of inorganic salts and acids, organic salts and acids or activated rosins or resins.

D

DEW POINT – The temperature at which water condenses out of an atmosphere for a given pressure.

DIFFERENTIAL THERMAL ANALYSIS – A test procedure for determining the solidus and liquidus temperatures of a material.

DIFFUSION BONDING – Se preferred terms diffusion brazing and diffusion welding.

DIFFUSION BRAZING (DFB) – A brazing process which produces coalescence of metals by heating them to suitable temperature and by using a filler metal. The filler metal may be distributed by capillary attraction or may be placed or formed at the faying surfaces. The filler metal is diffused with base metal to the extent that the joint properties have been changed to approach those of the base metal. Pressure may or may not be applied.

DIFFUSION HEAT TREATMENT – A thermal cycle, usually performed at 1065 to 1093 °C (1950 to 2000 °F) for two to four hours to cause migration of filler metal suppressants into the base metal. This effectively raises the remelt temperature and strengthens the joint.

DIP BRAZING (DB) – A brazing process in which the heat required is furnished by a molten chemical or metal bath. When a molten chemical bath is used, the bath may act as a flux.  When a molten metal bath is used, the bath provides the filler metal.

E

ELECTRIC BRAZING – See preferred terms resistance brazing and arc brazing.

EROSION (BRAZING) – A condition caused by dissolution of the base metal by molten filler metal resulting in a post- braze reduction in the thickness of the base metal.

EUTECTIC – (1) An isothermal reversible reaction in which a liquid solution is converted into two or more intimately mixed solids on cooling; the number of solids formed being the same as the number of components in the system .  (2) An alloy having the composition indicated by the eutectic point on an equilibrium diagram.  (3) An alloy structure of intermixed solid constituents formed by a eutectic reaction.  Refer to Silver - Copper Constitutional

F

FEED SIDE – The external face of an intended joint to which the main reservoir of the filler metal is added prior to the braze operation.

FILLER METAL – The metal to be added in making a welded, brazed or soldered joint.

FILLET – A radiussed area of a filler metal at the site where components are joined.

FISSURE – A small crack-like discontinuity with only slight separation (opening displacement) of the fracture surfaces. The prefixes macro or micro indicate relative size.

FLASH – The material which is expelled or squeezed of a joint.

FLAW – A near synonym for discontinuity, but with an undesirable connotation.

FLOW BRAZING (FLB) – A brazing process which produces coalescence of metals by heating them with molten, nonferrous filler metal poured over the joint until brazing temperature is attained. The filler metal is distributed in the joint by capillary attraction.

FLOWABILITY – The ability of molten filler metal to flow or spread over a metal surface.

FLUX – Material used to prevent, dissolve or facilitate removal of oxides and other undesirable surface substances.

FLUX COVER – In metal bath dip brazing and dip soldering, a cover of flux over the molten filler metal bath.

FREEZING POINT – See preferred terms liquidus and solidus.

FURNACE BRAZING (FB) – A brazing process in which the parts to be joined are placed in a furnace and heated to a suitable temperature.

FUSION – The melting together of filler metal and base metal (substrate) or of base metal only, which results in coalescence.

G

GAP – See joint clearance.

GAS BRAZING – See preferred term torch brazing.

H

HARD SOLDER – A term erroneously used to denote silver-base brazing filler metals.

HEAT-AFFECTED ZONE (HAZ) – The region of the base metal that has been thermally altered as a result of welding, brazing, soldering or thermal cutting processes.

HOLDING TIME – In brazing and soldering, the amount of time a joint is held within a specified temperature range.

HOT CRACK – A crack that develops during solidification.

HYDROGEN BRAZING – A term erroneously used to denote any brazing process which takes place in a hydrogen or hydrogen-containing atmosphere.

I

INADEQUATE JOINT PENETRATION – Joint penetration by the braze alloy that is less than specified.

 INCOMPLETE FUSION – A condition where all of the braze filler metal in a joint did not melt.

INDUCTION BRAZING (IB) – A brazing process in which the heat is obtained from the resistance of the work piece to induced electric current.

INFRARED BRAZING (IRB) – A brazing process in which the heat is furnished by infrared radiation.

INFRARED RADIATION – Electromagnetic energy with wave- lengths from 770 to 12,000 nanometers.

INTERGRANULAR PENETRAITON – The penetration of a filler metal along the grain boundaries of a base metal.

J

JOINT – The junction of members or the edges of members which are to be joined or have been joined.

JOINT BRAZING PROCEDURE – The materials, detailed methods and practices employed in the brazing of a particular joint.

JOINT CLEARANCE – The distance between the mating surfaces of a joint.  In brazing, this distance can vary during the brazing process as a result of thermal expansion.

JOINT DESIGN – The joint geometry together with the required dimensions.

JOINT EFFICIENCY – The ratio of the strength of a joint to the strength of the base metal (expressed in percent).

JOINT GEOMETRY – The shape and dimensions of a joint in cross-section prior to brazing.

L

LACK OF FUSION – See preferred term incomplete fusion.

LAP JOINT – A joint between two overlapping members.

LIQUATION – The separation of the low melting constituent(s) of an alloy from the remaining constituents, which is usually apparent in alloys having a wide melting range.  The remaining deposit no longer brazes at the established melting temperature.

LIQUIDUS – The lowest temperature at which a metal or an alloy is completely liquid.

M

MACHINE BRAZING – See preferred term mechanized brazing.

MANUAL BRAZING – A brazing operation performed and controlled completely by hand.

MECHANIZED BRAZING – Brazing with equipment which performs the brazing operation under the constant observation and control of a brazing operator.  The equipment may or may not perform the loading and unloading of the work.  Also see automatic brazing.

MELTING RANGE – The temperature range defined by the solidus and liquidus temperatures between which a brazing filler metal begins to melt and becomes completely fluid.

NONCORROSIVE FLUX – A brazing flux which, in its original or residual form, chemically attacks the base metal.  It usually is composed of rosin- or resin-base materials.

P

PARENT METAL – See preferred term base metal.

PARTIAL PRESSURE – In a closed system having a mixture of gases and vapors, the pressure a specific gas or vapor would exert if it occupied the entire volume of that mixture by itself.  A gas is often added to a vacuum atmosphere to prevent the vaporization of a filler metal or base material without increasing moisture or contamination levels.

PASTE SOLDERING FILLER METAL – A mixture of finely divided metallic solder with an organic or inorganic flux or neutral vehicle or carrier.

POST HEATING – The application of heat to an assembly after a brazing operation.

PREFORM – Brazing or soldering filler metal fabricated in a shape or form for a specific application.

PREHEAT(ing) – The heat applied to the base metal to achieve and maintain a preheat temperature. The application of heat to the base metal immediately before brazing.

PREHEAT TEMPERATURE – A specified temperature that the base metal must attain in the brazing area immediately before this operation is performed.

PROCEDURE – The detailed elements (with prescribed values or ranges of values) of a process or method used to produce a specific result.

PROACTIVE ATMOSPHERE – A  gas envelope surrounding the part to be brazed, with the gas composition controlled with respect to chemical composition, dew point, pressure, flow rate, etc.  Examples are inert gases, combustible fuel gases, hydrogen and vacuum.

R

REACTION FLUX – A flux composition in which one or more of the ingredients reacts with a base metal upon heating to deposit one or more metals.

REDUCING ATMOSPHERE – A chemically active protective atmosphere which, at an elevated temperature, will reduce metal oxides to their metallic state.   “Reducing atmosphere” is a relative term as an atmosphere may be reducing to one oxide but not to another oxide.

RESISTANCE BRAZING (RB) – A brazing process in which the heat required is obtained from the resistance to electric current in a circuit of which the work is a part.

S

SALT-BATH DIP BRAZING – A variation of the dip brazing process.

SANDWICH BRAZE – A brazed assembly of dissimilar materials where a preplaced shim, having a composition different than that of the filler metal, that serves as a transition layer to minimize thermal stresses.

SELF-FLUXING ALLOYS – Certain materials that “wet” the substrate and coalesce when heated to their melting point, without the addition of a fluxing agent.

SEMIAUTOMATIC BRAZING – Brazing with equipment which controls only the brazing filler metal feed.  The advance of the brazing is manually controlled.

SEMIBLIND JOINT – A joint in which one extremity of the joint is not visible.

SILVER SOLDERING, SILVER BRAZING – Nonpreferred terms used to denote brazing or soldering with a silver-base filler metal. See preferred terms furnace brazing, induction brazing and torch brazing.

SKULL – The unmelted residue from a liquated filler metal.

SOLDER – A filler metal used in soldering which has a liquidus not exceeding 450 °C (840 °F).

SOLDERING (S) – A group of processes that produces coalesced materials by heating them to a suitable temperature using a filler metal having a liquidus not exceeding 450 °C (840 °F) and below the solidus of the base metals. The filler metal is distributed between the closely fitted faying surfaces of the joint by capillary action.

SOLIDUS – The highest temperature at which a metal or alloy is completely solid.

STEP BRAZING – The brazing of successive joints on a given part with filler metals of successively lower brazing temperatures so as to accomplish the joining without disturbing the joints previously brazed. A similar result can be achieved at a single brazing temperature if the remelt temperature of prior joints is increased by metallurgical interaction.

STOPOFF – A material used on the surfaces adjacent to the joint to limit the spread of brazing filler metal while the filler metal is in a liquid state.

SUBSTRATE – The metal or material to be welded, brazed, soldered or cut.

T

THERMOCOUPLE – A device for measuring temperatures consisting of two dissimilar metals (the base metal and the thermocouple wire) which produce an electromotive force roughly proportional to the temperature difference between the ends of the hot and cold junctions.

TORCH BRAZING (TB) – A brazing process in which the heat required is furnished by a fuel gas flame.

V

VACUUM BRAZING – A term used to denote various brazing processes which take place in a chamber or retort below atmospheric pressure.

W

WELD BRAZING – A joining method which combines resistance welding with brazing.

WETTING – The phenomenon whereby a liquid filler metal or flux spreads and adheres in a thin continuous layer on a properly prepared solid base metal surface.

WICKING – Flashing of the brazing filler metal out of the joint onto adjacent areas, or the flow of brazing filler metal up the joint walls from a pre-placed deposit.

WORKPIECE – A part or an assembly that is brazed.

Gold
Silver
Platinum
Palladium