Tungsten carbide are widely used in industrial production due to their high hardness and excellent wear resistance. However, during manufacturing and usage, thermal internal stress can occur in hard alloy materials due to temperature changes, which negatively impacts their performance and service life.
Thermal internal stress in tungsten carbide materials is caused by differences in the thermal expansion coefficients of the material at varying temperatures. When cemented carbide materials cool from a high-temperature state to room temperature, uneven contraction rates and degrees lead to the formation of internal stress, known as thermal internal stress. The magnitude of thermal internal stress is influenced by factors such as the material's structure, composition, and processing techniques.
Annealing Method
Annealing is an effective method for eliminating thermal internal stress in hard alloy materials. The principle involves heating, holding, and slow cooling to alter the internal structure of the hard alloy, thereby relieving thermal internal stress.
In practice, the specific annealing method should be chosen based on the material's characteristics. Commonly used methods include medium-temperature annealing and high-temperature annealing. Medium-temperature annealing is suitable for general thermal internal stress, while high-temperature annealing is used for more significant thermal internal stress.
Precipitation Hardening Method
The precipitation hardening method eliminates thermal internal stress by adding specific alloying elements to modify the structure of the hard alloy material. The principle is that when suitable elements are added, they form tiny solid precipitates within the matrix.
These precipitates inhibit dislocation movement and enhance material strength, thereby relieving thermal internal stress. The advantage of this method is that it does not require complex heat treatment processes. However, it is crucial to select appropriate alloying elements and control the size and distribution of the precipitates.
Slow Cooling Method
The slow cooling method involves gradually cooling the hard alloy workpiece from a high-temperature state to room temperature, allowing the residual stress within the material to be released gradually, thereby eliminating thermal internal stress.
The advantage of this method is its simplicity, but it has limited applicability and is generally suitable only for low-grade hard alloys and simple-shaped components.
Sandblasting and vibration
Spraying the surface of cemented carbide with high-pressure gas or water can remove surface stress. Vibrating the cemented carbide with vibration equipment can release its stress.
When eliminating thermal internal stress in tungsten carbide materials, the following precautions should be taken:
1. Select appropriate processes and design parameters carefully.
2. Pay attention to the selection of measurement locations and directions when measuring thermal internal stress.
3. Control the annealing temperature and duration during annealing treatment.
4. Ensure strict composition and quality control when adding alloying elem
5. Regulate the cooling rate and temperature gradient during slow cooling treatment.
In conclusion, thermal internal stress is a common issue in tungsten carbide materials. However, it can be effectively eliminated through proper processing and treatment methods, thereby improving the performance and service life of hard alloy materials.for more information about tungsten carbide products,find us on www.ostoncarbide.com .
