Process for effecting metallurgical joints between two different metals and the products obtained thereby

Claim 2

A process for producing a tube made of two or more joined sections of two different metals having reciprocal metallurgical affinity, each section being made of a metal different from the adjoining sections, comprising the following steps: a. preparing two cylindrical hollow blocks of substantially the same length each made of one of said metals, and a casing made of a malleable metal, the inner diameter of one of said blocks being substantially equal to the outer diameter of the other block so that the blocks can be fitted one into the other; b. degassing and cleaning said blocks and casing; c. fitting said blocks one into the other to form a billet; d. enclosing said billet in said casing, producing a vacuum therein and sealing it vacuumtight; e. bringing said billet and casing at a plastic state by heating; f. extruding said billet to obtain a tube the wall of which is made of two layers of different metals, said layers being bonded together by a metallurgical bond, said tube being enclosed in a metal envelope obtained from said casing as a consequence of the extrusion; g. hot forming said tube to obtain a neck which is a gradual constriction of the tube symmetrical about its longitudinal axis,- or two necks at those locations along the tube where a transition joint is to be obtained in said metals, the longitudinal profile of said neck or necks being such that after the hot-forming operation the outer layer of the tube is brought in alignment with the inner layer, so that the length of the tube downstream of the neck up to the end of the tube has a constant cross section the outer diameter of which is equal to the outer diameter of the inner layer upstream of the neck; h. removing all that portion of the outer layer which exceeds the outer diameter of the inner layer upstream of the necks along that section of the tube which remained unchanged after the hot-forming step; and i. removing all those portions of the inner layer which inwardly exceed the inner diameter of the outer layer downstream of the necks.

Claim 3

A process according to claim 1 wherein step (a) also comprises forming a plurality of longitudinal wedgelike projections on that surface of the harder metal block which is intended to engage the corresponding surface of the Other block after the two blocks are fitted one into the other.

Claim 4

A process according to claim 1 wherein step (a) also comprises forming a plurality of wedgelike projections on those respective surfaces of the two blocks which reciprocally engage after the two blocks are fitted on into other.

Claim 5

A process according to claim 1 wherein said casing has the geometrical form of a cylindrical hollow tore.

Claim 6

A process according to claim 1 wherein the portions of the outer and inner layer to be removed according to steps (h) and (i) are removed by machining.

Claim 7

A process according to claim 1 wherein the portions of the outer and inner layer to be removed according to steps (h) and (i) are removed by chemical action.

Claim 8

A process as per claim 1 wherein the metals to be joined to form a tube consisting of adjoining sections of different metals are zirconium or its alloys and iron or its alloys.

Claim 9

A process for producing a tube made of two or more joined sections of two different metals having reciprocal metallurgical affinity, each section being made of a metal different from the adjoining sections, comprising the following steps: a. preparing a first cylindrical hollow block made of one of said metals; a pair of cylindrical hollow blocks made of the other of said metals, the inner diameter of said pair of blocks being roughly equal to the outer diameter of said first block and an additional block with the same inner and outer diameter as said pair of blocks but made of a third metal different from them and from said first block, the total axial length of said pair of blocks and additional block being substantially equal to the length of said first block and a casing made of malleable metal for enclosing said blocks in a continuous envelope; b. degreasing and cleaning said blocks and casing; c. fitting said pair of blocks and additional block around said first block, the additional block being interposed between the two blocks of said pair so that a single block or billet is obtained; d. enclosing said billet in said casing, producing a vacuum therein and sealing it vacuumtight; e. bringing said billet and casing to a plastic state by heating; f. extruding said billet to obtain a tube the wall of which is made of two continuous inner and outer layers, the inner one being made of one of said metals and the outer one being made of three contiguous sections of which two are made of the other of said metals and the third one which is intermediate to the outer two is made of a third metal different from both said metals, said layers being bonded together by a metallurgical bond; said tube being enclosed in a metal envelope obtained from said casing as a consequence of which extrusion; g. hot forming said tube to obtain a neck which is a gradual constriction of the tube symmetrical about its longitudinal axis or two necks at those locations along the tube where a transition joint is to be obtained of said metals; the diameter of the tube cross section being left unchanged along that section of the tube where the outer layer is made of said third metal, the longitudinal profile of said neck or necks being such that after the hot-forming operation the outer layer of the tube is brought in alignment with the inner layer, so that the length of the tube downstream of the neck until the end of the tube has a constant cross section the outer diameter of which is equal to the outer diameter of the inner layer upstream of the neck; h. removing all that portion of the outer layer which exceeds the outer diameter of the inner layer upstream of the necks that is along that section of the tube which remained unchanged after the hot-forming step; and i. removing all those portions of the inner layer which inwardly exceed the inner diameter of the outer layer downstream of the neck.

Claim 10

A process for producing a tube made of two or more joined sections of two different metals having reciprocal metallurgical affinity, each section being made of a metal different from the adjoining sections, comprising the following steps: a. preparing a first cylindrical hollow block made of one of said metals; a pair of cylindrical hollow blocks made of the other of said metals, the inner diameter of said pair of blocks being roughly equal to the outer diameter of said first block and an additional block with the same inner and outer diameter as said pair of blocks but made of a third metal different from them and from said first block, the total axial length of said pair of blocks and additional block being substantially equal to the length of said first block and a casing made of malleable metal for enclosing said blocks in a continuous envelope; b. degreasing and cleaning said blocks and casing; c. fitting said pair of blocks and additional block around said first block, the additional block being interposed between the two blocks of said pair so that a single block or billet is obtained; d. enclosing said billet in said casing, producing a vacuum therein and sealing it vacuumtight; e. bringing said billet and casing to a plastic state by heating; f. extruding said billet to obtain a tube the wall of which is made of two continuous inner and outer layers, the inner one being made of one of said metals and the outer one being made of three contiguous sections of which two are made of the other of said metals and the third one which is intermediate to the outer two is made of a third metal different from both said metals, said layers being bonded together by a metallurgical bond; said tube being enclosed in a metal envelope obtained from said casing as a consequence of which extrusion; g. hot forming said tube to obtain a neck which is a gradual constriction of the tube symmetrical about its longitudinal axis or two necks at those locations along the tube where a transition joint is to be obtained of said metals; the diameter of the tube cross section being left unchanged along that section of the tube where the outer layer is made of said third metal, the longitudinal profile of said neck or necks being such that after the hot-forming operation the outer layer of the tube is brought in alignment with the inner layer, so that the length of the tube downstream of the neck until the end of the tube has a constant cross section the outer diameter of which is equal to the outer diameter of the inner layer upstream of the neck; h. removing all that portion of the outer layer which exceeds the outer diameter of the inner layer upstream of the necks that is along that section of the tube which remained unchanged after the hot-forming step; and i. removing all those portions of the inner layer which inwardly exceed the inner diameter of the outer layer downstream of the neck.

Claim 11

A process according to claim 8 wherein step (a) also comprises forming a plurality of longitudinal wedgelike projections on tHat surface of the harder metal block or blocks which are intended for engaging the corresponding surfaces of the other blocks after the blocks are assembled together to form a billet.

Claim 12

A process according to claim 8, wherein step (a) also comprises forming a plurality of wedgelike projections on those surfaces of the blocks which are intended to reciprocally engage after the blocks are assembled together to form a billet.

Claim 13

A process according to claim 8, wherein said casing has the geometrical form of a cylindrical hollow tore.

Claim 14

A process according to claim 8, wherein the portions of the outer and inner layer to be removed according to steps (h) and (i) are removed by machining.

Claim 15

A process according to claim 8 in which the portions of the outer and inner layer to be removed according to steps (h) and (i) are removed by chemical action.

Claim 16

A process according to claim 8 in which the metals to be joined to form a tube consisting of adjoining sections of different metals are zirconium or its alloys and iron or its alloys.