Brazing clad material, and brazing method and brazing product using the same

1. A brazing clad material, comprising:

a composite material that comprises a base material and a brazing material layer formed integrally on the base material,

wherein the brazing material layer comprises a Ni or Ni alloy layer, a Ti or Ti alloy layer and a Fe—Ni alloy layer that are sequentially stacked in this order on the base material,

wherein the brazing material layer comprises a Fe concentration of 25 to 40 wt % in the entire brazing material layer,

wherein the brazing material layer satisfies a ratio of W 1 /W 2 to be 0.56 to 0.66, where W 1 is a weight of Ni contained in the entire brazing material layer and W 2 is a total weight of Ni and Ti contained in the entire brazing material layer,

wherein the brazing material layer comprises a diffusion reacting layer with a thickness of 2 to 6 μm, and

wherein the diffusion reacting layer is formed at an interface between two hetero-metals of the Ni or Ni alloy layer, the Ti or Ti alloy layer and the Fe—Ni alloy layer to compose the brazing material layer.

2. The brazing clad material according to claim 1 , wherein:

the composite material satisfies a ratio of T 2 /T 1 to be 0.05 to 0.12, where T 2 is a thickness of the brazing material layer and T 1 is a total thickness of the brazing clad material, as determined before cladding.

3. The brazing clad material according to claim 1 , wherein:

the Fe—Ni alloy layer comprises Fe-35 to 45 mass % Ni.

4. The brazing clad material according to claim 1 , wherein:

the base material comprises an alloy comprising Fe as a main component.

5. The brazing clad material according to claim 4 , wherein:

the alloy comprising Fe as a main component comprises a stainless steel.

6. A method of brazing the brazing clad material as defined in claim 1 to a brazed member, comprising the steps of:

preheating the brazing clad material at a temperature of 800 to 940° C. and

brazing the preheated brazing clad material to the brazed member in a vacuum atmosphere at a temperature of 1100 to 1200° C.

7. The method according to claim 6 , wherein:

the vacuum atmosphere comprises a vacuum degree of 1×10 −2 Pa or less.

8. The method according to claim 6 , wherein:

the vacuum atmosphere comprises a gas atmosphere substantially not containing N 2 gas and a vacuum degree of 1×10 −2 Pa or less.

9. A brazing product, comprising:

the brazing clad material as defined in claim 1 ; and

a brazed member,

wherein the brazing clad material is brazed to the brazed member.

10. A brazing product, comprising:

a brazing clad material, comprising:

a composite material that comprises a base material and a brazing material layer formed integrally on the base material,

wherein the brazing material layer comprises a Ni or Ni alloy layer, a Ti or Ti alloy layer and a Fe—Ni alloy layer that are sequentially stacked in this order on the base material,

wherein the brazing material layer comprises a Fe concentration of 25 to 40 wt % in the entire brazing material layer,

wherein the brazing material layer satisfies a ratio of W 1 /W 2 to be 0.56 to 0.66, where W 1 is a weight of Ni contained in the entire brazing material layer and W 2 is a total weight of Ni and Ti contained in the entire brazing material layer,

wherein the brazing material layer comprises a diffusion reacting layer with a thickness of 2 to 6 μm,

wherein the diffusion reacting layer is formed at an interface between two hetero-metals of the Ni or Ni alloy layer, the Ti or Ti alloy layer and the Fe—Ni alloy layer to compose the brazing material layer, and

wherein the brazing clad material is brazed to the brazed member by a method comprising the steps of:

preheating the brazing clad material at a temperature of 800 to 940° C. and

brazing the preheated brazing clad material to the brazed member in a vacuum atmosphere at a temperature of 1100 to 1200° C.