A technique for brazing graphite/graphite and stainless steel/high-carbon steel joints

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · Welding Journal (Miami); (United States)

OSTI ID:6897074

Ohmura, H; Kawashiri, K ^[1]; Yoshida, T ^[2]; Yoshimoto, O ^[3]

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1. Nagoya Municipal Industrial Research Inst. (Japan). Dept. of Metals and Inorganic Materials
2. Meijo Univ., Nagoya (Japan). Vehicle Machine Engineering Dept.
3. Toyo Tanso Co., Ltd., Ohnohara (Japan). Quality Control Dept.

A new brazing technique for joining graphite to itself or to metals such as Mo, W, or Cu, with conventional brazing filler metals has been developed. Essentially, it is impossible to braze graphite with Cu filler metal because no wetting occurs. However, when a graphite base material is combined with an Fe base metal in Cu brazing, the Fe base metal dissolves in molten Cu. Simultaneously, the dissolved Fe grows as part of a columnar Fe-9 [approximately] 6Cu-1.6C alloy phase at the graphite interface at a constant brazing temperature, that is, the dissolution and deposit of base metal takes place. By placing an Fe foil insert between both graphite base materials, therefore, the columnar phase is formed at both graphite faces and grows toward the Fe foil during heating. As a result, both graphite base materials are united by the columnar phase through the Fe foil. In the same way, a graphite/Mo or /W joint can be produced. Moreover, when using BAu-1, which has a lower melting point than that of BCu-1, it is also possible to braze graphite to Cu. The shear strength of a graphite/graphite joint with a 0.12-mm thick Fe foil at room temperature was about 32 MPa. Further, the bending strength of the graphite/graphite and /Cu joints at 873 K (1,112 F), as measured using the four-point bending test, was 35 and 11 MPa, respectively. In addition, the technique can be applied to the brazing of AISI 304 stainless steel to high-C steel with BCu-1 where, normally, Cr[sub 23]C[sub 6] and Cr[sub 7]C[sub 3] layers are formed at the high-C steel braze interface; these carbide layers result in the loss of mechanical properties of the joint.

• OSTI ID: 6897074
• Journal Information: Welding Journal (Miami); (United States), Journal Name: Welding Journal (Miami); (United States) Vol. 73:10; ISSN 0043-2296; ISSN WEJUA3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360103 -- Metals & Alloys-- Mechanical Properties
360601 -- Other Materials-- Preparation & Manufacture
360603 -- Materials-- Properties
ALLOYS
BRAZED JOINTS
BRAZING
BRAZING ALLOYS
CARBON
CARBON STEELS
COPPER
ELEMENTAL MINERALS
ELEMENTS
FABRICATION
GRAPHITE
HIGH ALLOY STEELS
IMPACT STRENGTH
IRON
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
MECHANICAL PROPERTIES
METALS
MINERALS
MOLYBDENUM
NONMETALS
SHEAR PROPERTIES
STAINLESS STEELS
STEELS
TRANSITION ELEMENTS
TUNGSTEN
WELDED JOINTS
WELDING