1. Laser power
The power directly affects the amount of powder that can be melted per unit time and the cladding efficiency. When other working parameters are determined, the power is too small, which may lead to incomplete melting of the powder, pitting after grinding and polishing, insufficient bonding force and low coating hardness; If the power is too high, the weld bead may be overfused, resulting in oblique wrinkles on the surface.
2. Powder feeding capacity
After the powder flow meets the laser, it absorbs the laser energy. The larger the powder amount, the more laser energy is absorbed. When the amount of powder is too large, the laser energy will be insufficient, the coating will not melt through, the pitting will appear after polishing, the matrix will not melt, the coating and the substrate will not achieve metallurgical bonding, resulting in coating peeling. Large powder amount and low powder utilization rate; Small powder amount and high powder utilization rate.
3. Linear velocity
The higher the linear velocity, the thinner the cladding. The smaller the linear velocity, the thicker the cladding. If the linear velocity is too high, the matrix cannot form a molten pool, the coating and the matrix cannot be metallurgical bonded, the cooling of the molten channel is slow, the red tail is too long, and peeling occurs. Low linear velocity can improve the hardness of coating and the utilization rate of powder.
4. Stepping
The smaller the step, the greater the lapping rate, and the finer the coating surface; The larger the step, the smaller the overlap rate, and the more obvious the coating stripe. The step affects the dilution ratio. When the step is small, the laser energy irradiated on the substrate is small and the dilution ratio is low; When the step is large, the laser energy irradiated on the substrate is large and the dilution rate is high.
5. Gas delivery
Gas has two functions, one is to transport powder, and the other is to protect high-temperature coating from oxidation. The powder feeding air volume is too small, which is easy to block the powder; The powder feeding volume is too large, the powder speed is too fast, the ejection is large, and the powder utilization rate is low. In general, argon gas has better protection to the coating than nitrogen gas, and the coating quality is higher.
6. Nozzle height
The nozzle is too high, the powder divergence is large, and the powder utilization rate is low; Too low, the nozzle is easy to stick powder during the cladding process.
Source: Zhongke Zhongmei
