Diffusion bonding of butt joints

Claim 2

A dynamic diffusion bonding method of butt joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. maintaining the two members to be joined in side-by-side relationship between a support means and a rotatable electrode with the joint between said members extending from said support means toward said electrode; b. exerting a localized pressure on successive increments of said members in the region of the joint therebetween by biasing said electrode against both of said members and toward the support means and concomitantly effecting relative movement between said members and said electrode; c. simultaneously with the exertion of said localized pressure, locally heating only the portions of the members on which the pressure is exerted in the regions of the members adjacent the joint therebetween, said heating being accomplished by passing an electrical current from said electrode through the members being butt joined to the supporting means; and d. so regulating the current density through the members being joined as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated in a region contiguous to the joint therebetween and produce sufficient expansion of the members toward each other and sufficient localized plastic flow of each of the members being joined to insure essentially complete metal-to-metal contact between said members over the area of said joint to permit a diffusion of atoms of the materials of which said members are composed across said joint which will produce a continuous bond between said members.

Claim 3

The method of claim 1, together with the step of interposing a metallic strip which is independent of the members being joined between the rotatable electrode and the members being joined, said strip being placed over the joint between said members.

Claim 4

The method of claim 2, together with the step of interposing a second metallic strip between the members being joined and the supporting means, said second strip also being independent of the members being joined and being placed over the joint between said members.

Claim 5

The method of claim 2, wherein said strip is of the same material as the members being joined.

Claim 6

The method of claim 2, together with the step of removing said strip after the members are joined.

Claim 7

The method of claim 1, together with the step of maintaining a reducing atmosphere in the region in which bonding takes place while said bond is being formed, said reducing atmosphere being maintained by disposing a shield adjacent the members being joined and effecting a flow of a reducing gas between said members and said shield.

Claim 8

A dynamic diffusion bonding method of joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing one of said members in a recess in the other of the members; b. disposing said members between a support means and a rotatable electrode; c. exerting a localized pressure on successive increments of said members by biasing said electrode against both of said members and toward the support means and concomitantly effecting relative movement between said members and said electrode; d. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted by passing an electrical current from said electrode through the members being joined to the supporting means; and e. so regulating the current density through the members being joined as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated to thereby produce sufficient expansion of the members toward each other and sufficient localized plastic flow of each of the members to insure essentially complete metal-to-metal contact between said members to thereby permit a diffusion of atoms of the materials of which said members are composed which will produce a continuous bond between said members.

Claim 9

A dynamic diffusion bonding method of joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing one of said members in a recess in the other of the members; b. disposing said members between a support means and a rotatable electrode; c. exerting a localized pressure on successive increments of said members by biasing said electrode against both of said members and toward the support means and concomitantly effecting relative movement between said members and said electrode; d. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted by passing an electrical current from said electrode through the members being joined to the supporting means; and e. so regulating the current density through the members being joined as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated to thereby produce sufficient expansion of the members toward each other and sufficient localized plastic flow of each of the members to insure essentially complete metal-to-metal contact between said members to thereby permit a diffusion of atoms of the materials of which said members are composed which will produce a continuous bond between said members.

Claim 10

A dynamic diffusion bonding method of joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing a filler member between the two members to be joined; b. maintaining the two members to be joined and the filler member in side-by-side relationship between a support means and a rotatable electrode with the joints between said first-mentioned members and the filler member extending from said support means toward said electrode; c. exerting a localized pressure on successive increments of said members in the region of the joints there-between by biasing said electrode against said members and toward the support means and concomitantly effecting relative movement between said members and said electrode; d. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted in the regions of the members adjacent the joints therebetween by passing an electrical current from said electrode through the members to the supporting means; and e. so regulating the current density through the members as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated in regions contiguous to the joints therebetween to thereby produce sufficient expansion of the members toward each other and sufficient localized plastic flow of the members to insure essentially complete metal-to-metal contact between said members over the areas of said joints to permit a diffusion of atoms of the materials of which said members are composed across said joints which will produce continuous bonds between each of the members being joined and the filler member.

Claim 11

A dynamic diffusion bonding method of joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing a filler member between the two members to be joined; b. maintaining the two members to be joined and the filler member in side-by-side relationship between a support means and a rotatable electrode with the joints between said first-mentioned members and the filler member extending from said support means toward said electrode; c. exerting a localized pressure on successive increments of said members in the region of the joints there-between by biasing said electrode against said members and toward the support means and concomitantly effecting relative movement between said members and said electrode; d. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted in the regions of the members adjacent the joints therebetween by passing an electrical current from said electrode through the members to the supporting means; and e. so regulating the current density through the members as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated in regions contiguous to the joints therebetween to thereby produce sufficient expansion of the members toward each other and sufficient localized plastic flow of the members to insure essentially complete metal-to-metal contact between said members over the areas of said joints to permit a diffusion of atoms of the materials of which said members are composed across said joints which will produce continuous bonds between each of the members being joined and the filler member.

Claim 12

A dynamic diffusion bonding method of butt joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing the two members to be joined in butting relationship between a support means and an electrode with the butting surfaces of said members extending from said support means toward said electrode; b. exerting a localized pressure on said members in the region of the joint therebetween by biasing said electrode against both of said members and toward the support means; c. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted in the regions of the members adjacent the joint therebetween by passing an electrical current frOm said electrode through the members being butt joined to the supporting means; and d. so regulating the current density through the members being joined as to maintain the maximum temperature of each of said members below the melting point of the material of which said members is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated in a region contiguous to the joint therebetween and produce an expansion of the members toward each other and localized plastic flow of each of said members to an extent such that there will be essentially complete metal-to-metal contact between said members over the area of said joint to permit a diffusion of atoms of the materials of which said members are composed across said joint to produce a continuous bond between said members.

Claim 13

A dynamic diffusion bonding method of butt joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing the two members to be joined in butting relationship between a support means and an electrode with the butting surfaces of said members extending from said support means toward said electrode; b. exerting a localized pressure on said members in the region of the joint therebetween by biasing said electrode against both of said members and toward the support means; c. simultaneously with the exertion of said localized pressure, locally heating the portions of the members on which the pressure is exerted in the regions of the members adjacent the joint therebetween by passing an electrical current frOm said electrode through the members being butt joined to the supporting means; and d. so regulating the current density through the members being joined as to maintain the maximum temperature of each of said members below the melting point of the material of which said members is composed and thereby prevent melting of the members but high enough to exceed the yield stress of the material from which each said member is fabricated in a region contiguous to the joint therebetween and produce an expansion of the members toward each other and localized plastic flow of each of said members to an extent such that there will be essentially complete metal-to-metal contact between said members over the area of said joint to permit a diffusion of atoms of the materials of which said members are composed across said joint to produce a continuous bond between said members.

Claim 14

A diffusion bonding method of butt joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing the two members to be joined in butting relationship between a support means and an electrode with the butting surfaces of said members extending from said support means toward said electrode; b. locally heating the portions of the member on which the pressure is exerted in the regions of the members adjacent the joint therebetween by passing an electrical current from said electrode through the members being butt joined to the supporting means; c. so regulating the current density through the members being joined so as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members; and d. simultaneously with the heating of the members being joined, exerting on said members in the region of the joint therebetween by biasing said electrode against both of said members and toward the support means a localized pressure of sufficient magnitude to, at the temperature to which the members being joined are heated, cause the metal from which the members being joined are formed to become plastic and to, in co-operation with the lower temperature portions of said members, constrain such metal against flow in directions other than toward the joint between the members, thereby producing an expansion of the plastic metal toward the joint which will result in essentially complete metal-to-metal contact between said members over the area of said joint and permit a diffusion of atoms of the materials of which said members are composed across said joint to produce a continuous bond between said members.

Claim 15

A diffusion bonding method of butt joining two metallic members into a unitary structure by forming a continuous bond therebetween, comprising the steps of: a. disposing the two members to be joined in butting relationship between a support means and an electrode with the butting surfaces of said members extending from said support means toward said electrode; b. locally heating the portions of the member on which the pressure is exerted in the regions of the members adjacent the joint therebetween by passing an electrical current from said electrode through the members being butt joined to the supporting means; c. so regulating the current density through the members being joined so as to maintain the maximum temperature of each of said members below the melting point of the material of which said member is composed and thereby prevent melting of the members; and d. simultaneously with the heating of the members being joined, exerting on said members in the region of the joint therebetween by biasing said electrode against both of said members and toward the support means a localized pressure of sufficient magnitude to, at the temperature to which the members being joined are heated, cause the metal from which the members being joined are formed to become plastic and to, in co-operation with the lower temperature portions of said members, constrain such metal against flow in directions other than toward the joint between the members, thereby producing an expansion of the plastic metal toward the joint which will result in essentially complete metal-to-metal contact between said members over the area of said joint and permit a diffusion of atoms of the materials of which said members are composed across said joint to produce a continuous bond between said members.

Claim 16

The method of claim 10, together with the step of mechanically restraining the members being joined against separation during the formation of the bond therebetween.

Claim 17

The method of claim 11, wherein the members being joined are restrained against separation by confining them in an appropriate jig.

Claim 18

The method of claim 10, together with the step of promoting the quality of the bond between the members being joined by, prior to the heating and application of pressure to the workpiece, centering over the joint therebetween and between said members and the electrode or the workpiece support or both, a thin metallic strip which will become plastic at said temperature and pressure.