Material composition differences

Cobalt-based alloys use cobalt (Co), chromium (Cr), molybdenum (Mo), etc. as the main elements, of which cobalt accounts for a higher proportion, and a certain amount of iron (Fe), carbon (C) and other elements are also added; 

Nickel-based alloys uses nickel (Ni) as the main element, and also adds chromium (Cr), molybdenum (Mo), copper (Cu), titanium (Ti), niobium (Nb) and other elements.

Processability differences

Cobalt-based alloys have good work hardening and annealing softening properties, and are easy to be processed into various shapes. They are suitable for machining parts using cobalt-based alloys. Nickel-based alloys have good processability and are easy to forge, extrusion and rotor forming processing, and are suitable for machining parts. Development and improvement of high-speed power machinery using nickel-based alloys.

1. Heat treatment:Both high-temperature alloys require heat treatment. They both adopt a heat treatment system of solid solution treatment + aging treatment. The complexity of the heat treatment process is the same.

2. Weldability: Both high-temperature alloys have good weldability. During brush seal welding, heat is easy to accumulate and cause deformation. It is recommended to use cobalt-based materials, which have high thermal conductivity, strong thermal conductivity, small expansion coefficient, and small deformation. , the welding fusion strength is better.

3. Turning processing: Satisfactory turning processing can be performed.

Both high-temperature alloys have good processability.

Performance differences

1. Corrosion resistance:

Cobalt-based alloys have excellent wear resistance, corrosion resistance and high temperature properties, and can maintain stable performance in extreme environments such as strong acid, strong alkali, high temperature and high pressure, and are suitable for manufacturing parts that need to withstand high loads and extreme environments;

Nickel-based alloys have good corrosion resistance and can maintain stability and integrity in a variety of corrosive media. They also have excellent high-temperature properties and can maintain high strength and toughness in high-temperature environments. But it is not suitable for highly corrosive acidified media.

2. Thermal stability:

Cobalt-based alloys have better high-temperature properties than nickel-based alloys and can be used at high temperatures above 1200°C for a long time, while nickel-based alloys can usually only be used at around 1000°C. Cobalt-based alloys have higher melting points and thermal conductivity, smaller thermal expansion after heating, and have advantages in thermal stability; nickel-based alloys have better resistance to oxidation and corrosion, but in high-temperature environments, cobalt The base alloy has better high-temperature oxidation resistance and high-temperature corrosion resistance.

3. Mechanical strength:

Cobalt-based alloys have excellent high-temperature strength and good thermal fatigue resistance, while nickel-based alloys have excellent ductility and processability, but their high-temperature strength and thermal fatigue resistance are slightly inferior to cobalt-based alloys. At room temperature, the strength of cobalt-based alloys is slightly lower, but the elongation is greater; nickel-based alloys have higher strength, but are more brittle, and should be used with caution in locations with impact. At high temperatures, when the temperature is 650°C, nickel-based alloys have higher strength, but are also more brittle, and are prone to breakage when used in impact situations. When the temperature rises to 900°C, the nickel-based superalloy can no longer be used, while the diamond-based superalloy still has a certain strength.

4. Mechanical stiffness:

The so-called stiffness is the ability of a material to resist deformation. The stiffness of nickel-based alloys is lower than that of cobalt-based alloys in all temperature ranges.

Usage

Cobalt-based alloys are often used to manufacture various parts and components under wear-resistant, corrosion-resistant, high-temperature and impact-resistant working conditions; nickel-based alloys are widely used in aviation, aerospace, energy, marine, environmental protection and other fields, especially The production of key components such as turbine blades and combustion chambers in aero engines.