Diffusion bonding method for corrosion-resistant materials

A diffusion bonding method for corrosion resistant materials comprising:

• disposing an insert material having a melting point of at most 1150 degrees C. and a thickness of 10-80 micrometers between the bonding interfaces of two members to be joined, the insert comprising, by weight %,
• Cr:
• 5-40%,
• one or more of Si:
• at most 8% and B:
• at most 4%, and
• a remainder of at least one of Fe and Ni and incidental impurities;
• and
• heating the bonding interfaces of the two members by high-frequency induction heating for at least 120 seconds at a temperature of 1150-1250 degrees C. in an atmosphere containing at most 200 ppm oxygen while applying a pressure of 0.5-2 kgf/mm.sup.2 to the bonding interfaces so as to melt the insert material, the materials to be joined comprising internally clad steel tubes comprising an outer tube of carbon steel of low alloy steel and an inner tube of stainless steel of high Ni alloy.

A diffusion bonding method for corrosion resistant materials comprising:

• disposing an insert material having a melting point of at most 1150 degrees C. and a thickness of 10-80 micrometers between the bonding interfaces of two members to be joined, the insert comprising, by weight %,
• Cr:
• 5-40%,
• one or more of Si:
• at most 8% and B:
• at most 4%, and
• a remainder of at least one of Fe and Ni and incidental impurities;
• and
• heating the bonding interfaces of the two members by high-frequency induction heating for at least 120 seconds at a temperature of 1150-1250 degrees C. in an atmosphere containing at most 200 ppm oxygen while applying a pressure of 0.5-2 kgf/mm.sup.2 to the bonding interfaces so as to melt the insert material, the materials comprising externally clad steel tubes comprising an outer tube of stainless steel of high-Ni alloy steel and an inner tube of carbon steel of low alloy steel.

A diffusion bonding method for corrosion-resistant, clad materials comprising:

• disposing an insert material between the bonding interfaces of said clad materials, the insert material having the following composition, by weight %,
• Cr:
• 5-40%,
• Mo:
• at most 10%
• one or more of Si:
• at most 8% and B:
• at most 4%, and
• a remainder of at least one of Fe and Ni and incidental impurities;
• and
• the clad material being a high Ni alloy clad material or a stainless steel clad material, the high Ni alloy having the following composition by weight %:
• C:
• 0.05-0.5%,
• Si:
• 1-2.5%,
• Mn:
• 0.1-1.5%,
• Ni:
• 20-45%,
• Cr:
• 22-30%,
• optionally one or more of Mo:
• 1.8-2.2%,
• Ti:
• 0.2-0.8%
• B:
• 0.002-0.007%, and Zr:
• 0.001-0.05%, and a remainder of Fe and incidental impurities,
• heating the bonding interfaces of said clad materials by high-frequency induction heating of 2-400 kHz at a temperature of 1150.degree.-1250.degree.C. in an atmosphere containing at most 200 ppm oxygen while applying a pressure of 0.5-2 kgf/mm.sup.2 to the bonding interfaces so as to melt the insert material.

A diffusion bonding method for corrosion resistant materials comprising:

• disposing an insert material having a melting point of at most 1150 degrees C. and a thickness of 10-80 micrometers between the bonding interfaces of two members to be joined, the insert comprising, by weight %,
• Cr:
• 5-40%,
• Mo:
• at most 10%,
• one or more of Si:
• at most 8% and B:
• at most 4%, and
• a remainder of at least one of Fe and Ni and incidental impurities;
• and
• heating the bonding interfaces of the two members by high-frequency induction heating for at least 120 seconds at a temperature of 1150-1250 degrees C. in an atmosphere containing at most 200 ppm oxygen while applying a pressure of 0.5-2 kgf/mm.sup.2 to the bonding interfaces so as to melt the insert material, the materials to be joined comprising internally clad steel tubes comprising an outer tube of carbon steel or low alloy steel and an inner tube of stainless steel or high Ni alloy.

A diffusion bonding method for corrosion resistant materials comprising:

• disposing an insert material having a melting point of at most 1150 degrees C. and a thickness of 10-80 micrometers between the bonding interfaces of two members to be joined, the insert comprising, by weight %,
• Cr:
• 5-40%,
• Mo:
• at most 10%,
• one or more of Si:
• at most 8% and B:
• at most 4%, and
• a remainder of at least one of Fe and Ni and incidental impurities;
• and
• heating the bonding interfaces of the two members by high-frequency induction heating for at least 120 seconds at a temperature of 1150-1250 degrees C. in an atmosphere containing at most 200 ppm oxygen while applying a pressure of 0.5-2 kgf/mm.sup.2 to the bonding interfaces so as to melt the insert material, the materials to be joined comprising internally clad steel tubes comprising an outer tube of stainless steel or high Ni alloy steel and an inner tube of carbon steel or low alloy steel.