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Showing papers on "Filler metal published in 1994"


Book
31 Dec 1994
TL;DR: Brazing fundamentals and elements of brazing are described in this paper, along with a discussion of the application and future of the process and its application in a wide range of applications.
Abstract: Preface. Brazing fundamentals. Parameters and elements of brazing. Brazing heating methods. Braze filler metal and base material families. Fluxes, atmospheres - types and forms. Joint design, tooling/fixturing, surface preparation, inspection and safety. Applications and future of the process. Appendix. Index.

109 citations


Book
24 Jan 1994
TL;DR: Control of Microstructures and Properties in Steel Arc Welds as discussed by the authors provides an overview of the most recent developments in welding metallurgy and illustrates how modern theories are capable of predicting the microstructure and properties of these joints.
Abstract: Control of Microstructures and Properties in Steel Arc Welds provides an overview of the most recent developments in welding metallurgy. Topics discussed include common welding processes, the thermal cycle during welding, defects that may occur during the welding process, the metallurgy of the material, metallurgical processes in the heat-affected zone and the fused metal, and the relationship between microstructures and mechanical properties. The book's final chapter presents examples of welded joints, illustrating how modern theories are capable of predicting the microstructure and properties of these joints. This book is an excellent resource for welding engineers, metallurgists, materials scientists, and others interested in the subject.

89 citations


Journal ArticleDOI
TL;DR: In this article, the joint tensile strength, fatigue resistance and microstructure of the brazed joints were determined, the latter by X-ray diffraction analysis, scanning electron microscopy-energy-dispersive spectroscopy and scanning microscopy.
Abstract: TiPd (ASTM grade 7) and Ti-6Al-4V alloys (where the composition is in approximate weight per cent) were brazed in a vacuum furnace, each to itself, by using a new rapidly solidified amorphous 25Ti-25Zr-50Cu brazing foil. The joint tensile strength, fatigue resistance and microstructure were determined, the latter by X-ray diffraction analysis, scanning electron microscopy-energy-dispersive spectroscopy and scanning microscopy. The joint tensile strength is close to that of each base metal. The fatigue properties of TiPd (grade 7) joints do not differ from those of this base metal. The microstructure and mechanical properties of the brazed joints depend on the brazing cycle conditions: a fine lamellar eutectic joint microstructure consisting of α-Ti and γ-[Ti(Zr)]2Cu (tetragonal MoSi2-type) phase is observed after brazing of Ti-6Al-4V alloy at 900 °C for 10 min, followed by fast cooling. This brazing operation results is high strength joints. Brazing at temperatures higher than 900 °C and/or with a relatively low cooling rate results in a coarse dendritic microstructure consisting of γ-[Ti(Zr)]2Cu and hexagonal λ Laves Cu2TiZr phases. Fine precipitations of γ-tetragonal phase in the α-Ti matrix were also observed in the transition area between the base metal and joint in this case. Joints with such microstructures are brittle and have a low strength. It is shown that fast cooling suppresses formation of the λ Laves brittle phase, thus resulting in high mechanical properties of the brazed joint.

59 citations


Patent
07 Sep 1994
TL;DR: An improved method of making a monolayer abrasive tool using a relatively low melting point, soft filler metal alloy braze which possesses sufficiently high yield strength combined with a relatively high ductility and low elastic modulus to produce an exceptional bond between a mon-layer of superabrasive particles and the tool substrate is described in this paper.
Abstract: An improved method of making a monolayer abrasive tool using a relatively low melting point, soft filler metal alloy braze which possesses sufficiently high yield strength combined with a relatively high ductility and low elastic modulus to produce an exceptional bond between a monolayer of superabrasive particles and the tool substrate. The steps of the brazing process include applying a layer of the filler metal alloy including a an active metal in either pre-alloyed or as a mixture with the metal alloy and a monolayer of superabrasive crystals over the filler metal layer. This assembly is heated in a mon-oxidizing atmosphere such as a vacuum to melt the alloy and braze bond the superabrasive particles to the tool substrate. The alloy bond formed possess the properties of a ductility of at least 20 percent elongation, an elastic modulus of less than 15×10 6 or less, and a yield strength preferably at least about 45,000 to 50,000 psi. A copper/silver based alloy including about 8 to 15 weight percent indium and 1 to 4 weight percent titanium is used in a preferred embodiment of the method disclosed.

43 citations


Patent
10 Feb 1994
TL;DR: In this article, a laser welding apparatus for clad welding the interior surface of a tube is described, which includes a rotating sleeve (324) positionable within the tube, a fiber optic cable (340) and a filler passage (386).
Abstract: A laser welding apparatus (320) for clad welding the interior surface of a tube (20) is disclosed. The apparatus includes a rotating sleeve (324) positionable within the tube. Located within the rotating sleeve is a fiber optic cable (340) and a filler passage (386). The fiber optic cable receives laser energy from a laser (344). The filler passage receives filler material from a fillermetal delivery system (330) that synchronously moves with the rotating sleeve. Positioned at the end of the rotating sleeve is a welding head (322) which includes a head aperture (394) and a laser energy directional modification assembly (392). The laser energy from the fiber optic cable is transferred through the laser energy directional modification assembly and through the head aperture to a selected weld location on the interior surface of the tube. The filler metal from the filler metal delivery system is also conveyed through the head aperture and intersects with the laser energy at the selected weld location. The filler metal fuses with the interior surface of the tube to produce a clad weld.

42 citations


Patent
14 Jan 1994
Abstract: An improved welding method is provided for repairing broken rotors. The welding method preferably employs a 2.25Cr-1.0Mo-0.3V-type filler metal, preferably deposited using a narrow groove welding technique. The broken pieces are aligned end to end. A narrow groove is formed to substantially remove the end surfaces. The groove is preheated, filled with the welding filler metal, and postheated, resulting in a strong, high temperature resistant, long lasting weld.

29 citations


Patent
07 Feb 1994
TL;DR: In this paper, a laser welding apparatus for clad welding the interior surface of a tube is disclosed, which includes a rotating sleeve positionable within the tube, a fiber optic cable and a filler passage.
Abstract: A laser welding apparatus for clad welding the interior surface of a tube is disclosed. The apparatus includes a rotating sleeve positionable within the tube. Located within the rotating sleeve is a fiber optic cable and a filler passage. The fiber optic cable receives laser energy from a laser. The filler passage receives filler material from a filler metal delivery system that synchronously moves with the rotating sleeve. Positioned at the end of the rotating sleeve is a welding head which includes a head aperture and a laser energy directional modification assembly. The laser energy from the fiber optic cable is transferred through the laser energy directional modification assembly and through the head aperture to a selected weld location on the interior surface of the tube. The filler metal from the filler metal delivery system is also conveyed through the head aperture and intersects with the laser energy at the selected weld location. The filler metal fuses with the interior surface of the tube to produce a clad weld.

28 citations


Patent
16 Aug 1994
TL;DR: In this article, a shielding gas is proposed which in addition to argon and/or helium comprises a carbon dioxide fraction or an oxygen fraction or a fraction of a mixture of these gases of from 0.01 to 0.7 % by volume.
Abstract: The invention relates to a shielding gas arc welding method for non-ferrous materials, in particular aluminium materials and aluminium alloys, for example AlSi, which method comprises the continuous supply, during welding operation, of a shielding gas containing argon and/or helium to the weld spot (welding point) adjacent to the electrode. According to the invention, a shielding gas is proposed which in addition to argon and/or helium comprises a carbon dioxide fraction or an oxygen fraction or a fraction of a mixture of these gases of from 0.01 to 0.7 % by volume, preferably from 0.01 to 0.1 % by volume (from 100 to 7000 or 1000 ppm, respectively).

24 citations


BookDOI
01 Jan 1994

18 citations


Journal ArticleDOI
TL;DR: In this article, the thermal profiles for the autogenous weldment were calculated based on a two parameter model of laser welding that utilises the fusion zone boundary as a measure of best fit.
Abstract: Laser beam welding of 13 mm plates of HY 80 steel resulted in different microstructures in the fusion zone depending on the welding process. Autogenous welds resulted in an untempered martensitic structure, whereas, with the introduction of a hot wire filler metal, the microstructures depended on the wire feed. A slow feed resulted in a mixed martensite–bainite microstructure and a fast wire feed resulted in a microstructure that is primarily acicular ferrite. The chemistry of the as deposited weld metals was different in each case. The thermal profiles for the autogenous weldment were calculated based on a two parameter model of laser welding that utilises the fusion zone boundary as a measure of ‘best fit’. Based on the cooling rate of the autogenous fusion zone, cooling rates for the two welds with hot wire filler metal were rationalised. Using these cooling rates, the chemistry of the weld metal and a model of microstructural development of the weld metal, a computer calculation was made which...

17 citations


Journal Article
TL;DR: The most widely specified weldable aluminum alloys are Alloy 6061, 5083, 5052, and 5454 as discussed by the authors, which is a combination of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. Dickerson put the cut-off point in weldability at 3.5% magnesium.
Abstract: The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition canmore » be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.« less

Journal ArticleDOI
TL;DR: In this paper, a series of Al-Ge-Si-Mg system based filler metales was developed for sound and high strength brazing of these materials, and an evaluation of brazed joint strength of A5052 and A6061 base alloys with these filler metals were performed.
Abstract: Vacuum brazing of A5000 (Al-Mg) series and A6000 (Al-Mg-Si) series aluminum alloys are considerably difficult because of their rather high magnesium contents. For the purpose of sound and high strength brazing of these materials, a series of Al-Ge-Si-Mg system based filler metales was developed by the authors. Evaluations of brazed joint strength of A5052 and A6061 base alloys with these filler metals were performed and the relationship between the joint strength and the brazing conditions was investigated.In A6061 base alloy, the brazed joints provided sufficient joint strength which were equal to that of the base alloy. In A5052 alloy, on the other hand, the joint strength was considerably low which was as low as one half of that of the base alloy.The examination of brittle intermetallic compound Mg2Ge through the reaction between Mg in the base alloys and Ge in the filler metals occured at the interfaces of the brazed joints. Accordingly the formation of this intermetallic compound lead the decrease in the joint strength of A5052 alloy, which contains much Mg.

Journal ArticleDOI
TL;DR: In this article, the joining of vanadium and CC composites to stainless steel (SS) by resistance heat brazing was investigated, and the use of interlayers was found to reduce residual stresse in the high strength composite to SS joints.

01 Jan 1994
TL;DR: In this article, the TIG welding of duplex and super duplex stainless steels is discussed with particular reference to obtaining the optimal phase balance between austenite and ferrite.
Abstract: The TIG welding of duplex and super duplex stainless steels is discussed with particular reference to obtaining the optimal phase balance between austenite and ferrite. This is mainly achieved by control of the cooling rate and the weld chemistry. The latter is dependent upon the filler were chosen and the shielding gas used. The authors highlight the effects that N2 additions to the argon shielding gas have on the weld metal composition and the resultant microstructure.

Patent
01 Feb 1994
TL;DR: In this article, the authors proposed to provide a ceramics-metal joining body satisfying sufficient high joining strength and high reliability for a cooling-heating cycle or the like, by joining a metal member to a nitride based ceramic member through a Ag-Cu brazing filler metal layer containing at least one kind of an active metal selected among Ti, Zr, Hf and Nb compounds.
Abstract: PURPOSE:To provide a ceramics-metal joining body satisfying sufficient high joining strength and high reliability for a cooling-heating cycle or the like CONSTITUTION:The ceramics-metal joining body is obtained by joining a metal member to a nitride based ceramic member through a Ag-Cu brazing filler metal layer containing at least one kind of an active metal selected among Ti, Zr, Hf and Nb A compound, mainly nitride particles which are the reaction product of the active metal in the brazing filler metal with the nitride based ceramic member are present in layers in the joining boundary of the nitride based ceramic member side The compound particles containing the active metal are spherical particulates large in stress relaxation effect and <=100nm in diameter

Patent
06 Dec 1994
TL;DR: In this article, a new and improved process and exothermic reaction mixture for use in the process for producing molten weld metal is presented, where a reactant mixture is provided which has a reducing agent, a filler metal which does not react with any of the compounds of the mixture and two or more metallic compounds which are exothermically reduced by the reducing agent.
Abstract: The invention provides a new and improved process and exothermic reaction mixture for use in the process for producing molten weld metal. The molten weld metal is used in joining one non-ferrous metal piece with at least one other metal piece. The process and exothermic reaction mixture have distinct advantages over the prior art. These advantages include a higher filler metal yield, reduction of odor, and a higher quality corrosion resistant weld. These advantages are accomplished by a process wherein a reactant mixture is provided which has a reducing agent, a filler metal which does not react with any of the compounds of the mixture, and two or more metallic compounds which are exothermically reduced by the reducing agent. The metallic compounds subsequently form a compound, with the reducing agent, having a high heat of formation which provides an exothermic reaction with sufficient heat to melt the filler metal. The reactant mixture is exothermically reacted to release heat and melt the filler metal and provide a flow of filler metal from the reactant and product mixture which may be contacted with objects to be welded by the filler metal.

Journal ArticleDOI
TL;DR: In this paper, it was shown that keyhole welding of plastics is limited to the very restricted set of plastics that have a boiling point and volume heating, a mechanism that is not applicable to metals, is restricted to plastics with a good transparency for the incident radiation.
Abstract: Deep penetration welding and cutting of metals can be carried out at high speed with relatively low laser power. The efficient coupling of the laser radiation to the metal is due to the formation of a “keyhole.” Over the years, an attempt has been made to transfer the results on metals to plastics. It will be shown here that keyhole welding of plastics is limited to the very restricted set of plastics that have a boiling point. Volume heating, a mechanism that is not applicable to metals, is restricted to plastics with a good transparency for the incident radiation and with a high optical quality. Finally, surface heating is shown to be the most common mechanism for heating plastics.

Patent
10 May 1994
TL;DR: In this paper, the welding conditions set at the time of welding and further, obtaining the heat gain, a bead shape and an arc phenomenon figure are used to judge prediction and propriety of welding.
Abstract: PURPOSE:To judge prediction and propriety of welding by selecting welding conditions set at the time of welding and further, obtaining the heat gain, a bead shape and an arc phenomenon figure CONSTITUTION:At the time of selecting the arc welding conditions, the welding conditions are selected from an operation part 1, the necessary information such as materials 6 to be welded, a groove shape 7, a welding position value 8, a welding method 9 and filler metal 10 is set, the welding data and processed results are subjected to arithmetic processing by the information of a storage part 3 stored temporarily and the conditions set here and the welding conditions 13, the heat input 15, a bead shape 19, the arc phenomenon figure 21 and a bead lamination figure 17 are outputted to a display part 4, as necessary Consequently, the welding conditions 13 is selected automatically and the handling time of condition retrieval by the manual aid is saved

Journal ArticleDOI
TL;DR: In this article, various types of void formed in wide gap brazed joints of C1023 nickel base superalloy produced using prepacks of nickel base braze mixes have been investigated and systematically categorised.
Abstract: The various types of void formed in wide gap brazed joints of C1023 nickel base superalloy produced using prepacks of nickel base braze mixes have been investigated and systematically categorised. Of particular interest are interfacial and interstitial voids and unwetted pockets, which are features frequently found in joints brazed using such a technique. Examination of brazed joints produced under a wide range of conditions revealed that during heating to the brazing temperature, the braze mix partially sinters together, causing the prepack to shrink towards the centreline, leaving two channels next to the joint faying surfaces. At the same time, relatively large pockets of free space are created within the partially sintered mass of prepack. At the brazing temperature, the filler metal deposited at the gap mouth becomes molten and this molten filler is drawn into the gap preferentially through the fine capillary paths in the partially sintered mass of prepack. The relatively large pockets of fre...

Patent
22 Mar 1994
TL;DR: In this paper, a flux is stuch to both surfaces or one surface of the sheet or foil 1 consisting of the Al alloy brazing filler metal components, by which the flux is wound to the circular columnar shape.
Abstract: PURPOSE:To eliminate the variations in a flux supply rate and to improve brazeability and the appearance quality and surface treatability of brazed articles by sticking a flux to the surface of a sheet or foil consisting of an Al alloy and winding the sheet or foil to a circular cplumnar shape. CONSTITUTION:The flux 2 is stuch to both surfaces or one surface of the sheet or foil 1 consisting of the Al alloy brazing filler metal components. This sheet or foil is wound to the circular columnar shape, by which the flux-contg. Al alloy brazing filler metal is formed. The flux 2 wound into the spacings of the sheet or foil 1 is melted and supplied to joint parts if this brazing filler metal is melted by heating at the time of brazing and, therefore, the oxide in the joint part is removed by the effect of the flux 2 and the brazing filler metal is wetted and spread, by which the secure joining by brazing is attained. The good brazing is attained even if the flux is not separately supplied to the joint part.


Patent
08 Jun 1994
TL;DR: In this article, a mixture of metal alloy powders, such as a nickel- or cobalt-based braze filler metal, homogeneously dispersed throughout an aqueous gel solution comprising a binder such as cellulose material, for example, sodium carboxymethyl-cellulose and a dispersants such as mineral oil and glycerine.
Abstract: A braze filler metal alloy paste containing braze metal alloy powders, such as a nickel- or cobalt-based braze filler metal, homogeneously dispersed throughout an aqueous gel solution comprising a binder such as a cellulose material, for example, sodium carboxymethyl-cellulose and a dispersants such as mineral oil and glycerine.

Journal ArticleDOI
TL;DR: In this article, a hot-pressed Si3N4 was brazed to 410-stainless steel using a Ag-Cu-Ti alloy foil in a vacuum.
Abstract: Hot-pressed Si3N4 was brazed to 410-stainless steel using a Ag-Cu-Ti alloy foil in a vacuum. The occurrence of cracking due to processing was examined by systematically varying the brazing temperature and time between 840 and 900 °C and 6 and 60 min, respectively. Cracks were found in Si3N4 parallel to the bonding interface when the braze joints were processed at the lower temperatures (for all processing times at 840 °C and for times of 6 and 12 min at 860 °C). A reaction layer was observed to develop in the filler metal adjacent to Si3N4, rich in Ti and containing some Si. The thickness of this layer depended on brazing temperature and time. Microcracks were found in the reaction layer normal to the bonding interface in the joints processed at higher brazing temperatures (880 °C for 60 min and at 900 °C for 30 and 60 min). The low temperature cracks occurred, apparently, as a result of the incomplete relaxation of thermal stresses due to the presence of a hard continuous titanium strip in the filler metal; the high temperature microcracks seemed to be affected by the increase in thickness of the reaction layer and by the precipitation of intermetallic compounds. The compressive shear strength of the braze joints were evaluated and correlated with the cracking behaviour and microstructure changes in the joint. A strong braze joint was obtained when the reaction layer was relatively thin and no cracks were present in either the reaction layer or the Si3N4.

Patent
22 Feb 1994
TL;DR: In this paper, the active Ag brazing filler metal has the structure formed by dispersing intermetallic compd. particles having =22 kinds among Hf, Zn, Zr, Be and Li at need, consisting of the balance Ag and inevitable impurities.
Abstract: PURPOSE:To provide the active Ag brazing filler metal by which the excellent characteristics and high reliability for brazing ceramics to ceramics, ceramics to metal, or metal to metal are obtd. CONSTITUTION:This active Ag brazing filler metal has the structure formed by dispersing intermetallic compd. particles having =22 kinds among Hf, Zn, Zr, Be and Li at need, consisting of the balance Ag and inevitable impurities.


Patent
Shigeru Shimogama1
31 Mar 1994
TL;DR: In this paper, a method of operating an arc welding apparatus which controls and moves a welding wire of a welding torch and detects a weld between a work and the welding wire after completion of arc welding is described.
Abstract: A method of operating an arc welding apparatus which controls and moves a welding wire of a welding torch and detects a weld between a work and the welding wire after completion of an arc welding, includes: a first step of cutting off a welding voltage to the welding wire to thereby extinguish a welding arc; a second step of detecting a weld state between the welding wire and the work; a third step of lifting the welding wire away from the work when the welded state is detected at the second step; a fourth step of detecting the welded state between the welding wire and the work after completion of the third step; a fifth step of impressing the welding voltage to the welding wire when a welded state has been detected at the fourth step; a sixth step of detecting the welded state between the welding wire and the work after completion of the fifth step; a seventh step of executing, when the welded state has been detected at the sixth step, at least one of the stopping of the operation of the arc welding apparatus, displaying of the welded state, and informing an operator of the welded state; and an eighth step of moving the apparatus to another location when the welded state has not been detected at the second, fourth, and sixth steps.

Patent
25 Oct 1994
TL;DR: In this article, the brazing of a tube made of Al alloy with a joint made of Alloy Alloy is described, and the filler metal and the part to be joined are set in a freely inserting/removing manner through the part B where a part of the coil is lost inside the high frequency induction heating coil.
Abstract: PURPOSE:To uniformly and easily execute the brazing of a tube made of Al alloy of complicated shape as the member for a heat exchanger of an automobile with a joint made of Al alloy by those other than skilled engineers, to execute the brazing work in the automated line, and to improve the productivity because the heating time is short. CONSTITUTION:In the brazing method where a tube 6 made of Al alloy is combined with a joint 7 made of Al alloy, the brazing filler metal is placed at the part A to be joined, and the brazing filler metal and the part to be joined are joined by executing the high frequency induction heating, the part to be joined is set in a freely inserting/removing manner through the part B where a part of the coil is lost inside the high frequency induction heating coil 8 which partly surrounds the circumference of the part A to be joined, and the induction-heated tube made of Al alloy is brazed with the joint.

Journal ArticleDOI
TL;DR: In this paper, the phase evolution and microstructural characteristics of chemical reaction products formed in the interface between the commercial alumina and the Ti-containing brazing filler metal at various heat-treatment conditions were investigated.
Abstract: Ceramic-to-metal (C/M) joining is of particular importance because of physical and economic limitations that restrict the size and complexity of ceramic components. The active filler metal method is one of the C/M joining techniques and involves the use of elements with a strong affinity for O[sub 2], e.g., Ti or Zr. Active metal elements, typically Ti, have been shown to be effective in wetting various oxides. In the Ag-Cu-Ti/Al[sub 2]O[sub 3] system the primary concern has been focused on the formation of Ti-contained phases as a result of chemical reaction between Al[sub 2]O[sub 3] and the Ti-containing brazing alloy. Previous studies suggested that Ti in brazing alloy reacts with the Al[sub 2]O[sub 3] ceramic surface to form compounds such as TiO. These compounds act as a transition layer between the Al[sub 2]O[sub 3] and the brazing alloy. The chemical reaction products at the C/M interface are important because they influence the mechanical strength of the joint. These products are affected by the composition of the brazing alloy and the process conditions such as the heat-treatment temperature and time. Consequently, microstructural studies of interfacial reaction products must be carried out to understand the relationships between the structure and the properties ofmore » the joint. The purpose of the present study is to investigate the phase evolution and the microstructural characteristics of chemical reaction products formed in the interface between the commercial alumina and the Ti-containing brazing filler metal at various heat-treatment conditions.« less

Patent
24 Aug 1994
TL;DR: In this paper, the authors proposed a thin aluminum alloy composite material for a heat exchanger with a three-layer structure in which one side of a core material 7 is clad with a brazing filler metal 9 and the other side is clothed with a sacrificial material 8.
Abstract: PURPOSE: To produce a thin aluminum alloy composite material excellent in fatigue strength and corrosion resistance. CONSTITUTION: This aluminum alloy composite material is the one in which, in an aluminum alloy composite material for a heat exchanger with a three- layered structure in which one side of a core material 7 is clad with a brazing filler metal 9 and the other side is clad with a sacrificial material 8, the core material 7 is constituted of an aluminum alloy contg., by weight, 0.05 to 3.0 to 6.0% Zn, and the balance Al with inevitable impurities, and furthermore, the hardness of the sacrificial material 8 after brazing heating is regulated to the hardness of the core material 7 or above. Since the sacrificial material 8 is compositionally excellent in corrosion resistance and the hardness of the sacrificial material 8 is regulated to the hardness of the core material 7 or above, cracks are hard to generate on the surface under vibration, and it is excellent in fatigue strength even in the case of being thin.