What Are The Common Defects in Laser Cladding Processing

Common defects that may occur in laser cladding processing and their causes are as follows, and understanding these defects can help to take preventive measures to improve processing quality and success rate:

First, cracks: this is one of the more serious defects, mainly caused by the following reasons:

1, thermal stress: due to the mismatch between the thermal expansion coefficient between the substrate and the coating, stress concentration occurs during the cooling process.

2, cooling speed: If the cooling is too fast, the residual stress in the material can not be released, it may also cause cracks.

3, improper alloy composition: the content of some elements is too high, reducing the ductility of the material.

Second, pores: the existence of holes reduces the effective coverage area and weakens the coating strength:

1, powder gas: the gas mixed in the raw material expands at high temperature to form bubbles.

2, poor atmosphere control: oxygen or water in the processing environment can also react with molten metal to produce gas.

3, powder moisture: excessive humidity powder melting will decompose and produce pores.

3. Non-fusion: insufficient combination of coating and substrate or layer, usually caused by the following factors:

1, insufficient power: laser energy is not enough to make the material reach a molten state.

2, the scanning speed is too fast: there is not enough time for the material to fully integrate.

3, poor surface pretreatment: there is oil on the surface of the substrate, oxides hinder good contact.

Fourth, segregation: uneven distribution of coating components, affecting the overall performance:

1, poor fluidity: some materials due to different particle size and uneven deposition.

2, phase separation: the component phase of the molten pool is separated, resulting in inconsistent microstructure.

5. Dilution: Excessive penetration of the substrate metal into the cladding layer changes the expected alloy ratio:

1, the laser penetration depth is too large: the underlying material is too melted, changing the coating formula.

2, improper scanning strategy: wrong scanning sequence or repeated strafing of the same area, increasing the amount of substrate mixing.

6. Preventive Measures:

1, carefully control the laser power, scanning speed, lap rate and other parameters to ensure process stability.

2, strict screening of powder materials, check the purity and dryness, to ensure consistency.

3. Strengthen surface pretreatment to remove all contaminants and provide a clean cladding platform.

4, the use of atmosphere control equipment, such as inert gas protection, to reduce oxidation and pollution risks.

5. Regularly calibrate the laser and powder feeding system to maintain the consistency of the processing environment.

By understanding and preventing these potential problems, the success rate of laser cladding processing can be greatly improved to produce high-quality coated parts that meet high engineering requirements. Correct process design and operation is an important measure to ensure product quality.