Cobalt-based cast high-temperature alloys
Cobalt-based cast high-temperature alloys with cobalt as the base. Chromium carbides and carbonitrides are the main strengthening phases of the alloy.
The strength level of cobalt-based cast high-temperature alloy is slightly lower than that of nickel-based cast high-temperature alloy . However, it has excellent thermal fatigue properties and oxidation and corrosion resistance at high temperatures, and is therefore particularly suitable for making gas turbine guide vanes that work below 1000°C. It has stable organization and good casting performance in long-term aging at 800℃, and can be cast into hollow blades and other parts with complex shapes. However, due to the shortage of cobalt resources, the application is limited.
(1) Forming performance
Casting performance is better than austenitic stainless steel, with the investment casting method can be cast into thin-walled hollow blades and other parts.
(2) welding performance
(1) with inert gas arc welding has very good welding performance. Generally do not use oxyacetylene welding. Connection K640 alloy itself available K640 welding rod and other alloys should be connected to the preferred choice of HastelloyW alloy welding rod. Before welding large parts require preheating within 371-427 ℃ to avoid post-welding cracking. Generally, V-type connection is used, but U-type connection is recommended for parts subjected to high stress.
2）When welding with protective atmosphere, it is recommended that welding from both sides should not increase the size of the weld, and copper blocks should not be used as a liner.
(3) When welding with direct current solitary welding, better mechanical properties can be obtained. To prevent cracking, it is recommended to use inclined electric solitary round-trip overlay welding.
(3) Parts heat treatment process
Parts used in the cast state
The strength level of cobalt-based cast high-temperature alloy is slightly lower than that of nickel-based cast high-temperature alloy . However, it has excellent thermal fatigue properties and oxidation and corrosion resistance at high temperatures, and is therefore particularly suitable for making gas turbine guide vanes that work below 1000°C. It has stable organization and good casting performance in long-term aging at 800℃, and can be cast into hollow blades and other parts with complex shapes. However, due to the shortage of cobalt resources, the application is limited.
(1) Forming performance
Casting performance is better than austenitic stainless steel, with the investment casting method can be cast into thin-walled hollow blades and other parts.
(2) welding performance
(1) with inert gas arc welding has very good welding performance. Generally do not use oxyacetylene welding. Connection K640 alloy itself available K640 welding rod and other alloys should be connected to the preferred choice of HastelloyW alloy welding rod. Before welding large parts require preheating within 371-427 ℃ to avoid post-welding cracking. Generally, V-type connection is used, but U-type connection is recommended for parts subjected to high stress.
2）When welding with protective atmosphere, it is recommended that welding from both sides should not increase the size of the weld, and copper blocks should not be used as a liner.
(3) When welding with direct current solitary welding, better mechanical properties can be obtained. To prevent cracking, it is recommended to use inclined electric solitary round-trip overlay welding.
(3) Parts heat treatment process
Parts used in the cast state
Solid solution reinforced alloys
Casting alloys
Single crystal alloy
Nickel-based single crystal alloy
Directional crystalline high temperature alloys
Deformed high temperature alloys
Powder Metallurgy High Temperature Alloys
Iron-based cast high-temperature alloys
Nickel-based cast high-temperature alloys