High-Speed Laser Cladding Equipment: Analysis of Core Quality Inspection Parameters for Cladding Layers

Porosity: Core Indicator of Cladding Layer Density for Laser Cladding Equipment

 

Porosity is a fundamental parameter for measuring the density of coatings prepared by high-speed laser cladding equipment. It refers to the percentage of the volume of pores in the cladding layer to the total volume of the cladding layer under specific inspection conditions (such as metallographic observation, X-ray flaw detection). Excessive porosity directly reduces the strength of the cladding layer and increases corrosion risk, and its occurrence is closely linked to the operating parameters of the laser cladding equipment: when the powder feeding speed of the equipment is too slow, the metal powder stays above the molten pool for an extended period, easily leading to uneven mixing with the protective gas and resulting in gas being trapped in the molten pool; if the laser energy density of the equipment is improperly controlled, the molten pool solidifies too quickly, leaving no time for gas to escape and thus forming closed pores. In addition, the moisture content and particle state of the metal powder adapted to the equipment also indirectly affect porosity through the equipment's conveying system. Therefore, it is necessary to optimize powder selection and powder feeding parameters in accordance with the equipment's characteristics.

Hardness: Mechanical Advantage of Laser Cladding Equipment Under Rapid Cooling Characteristics

 

Hardness, commonly expressed in Rockwell Hardness (HRC), is a key indicator for evaluating the wear resistance of the cladding layer. Its performance advantage stems from the "rapid cooling effect" of high-speed laser cladding equipment. Such equipment concentrates laser energy to heat the molten pool at a millisecond-level rate, while the low temperature of the substrate creates a large temperature gradient, enabling the cladding layer to solidify at a cooling rate exceeding 10³℃/s. This inhibits grain growth and causes lattice distortion, ultimately increasing hardness. For example, in industrial applications, when the LT series high-speed laser cladding equipment is matched with special wear-resistant powder, the surface hardness of the cladding layer can stably reach 60HRC, far higher than that of ordinary carbon steel. This characteristic makes the equipment widely applicable to the processing of wear-resistant components such as mining machinery and rolling rolls, and its hardness performance directly depends on the equipment's precise control of laser energy and cooling rate.

Bonding Strength: Core Manifestation of Metallurgical Bonding Achieved by Laser Cladding Equipment

 

Bonding strength, measured in megapascals (MPa), determines whether the cladding layer is prone to peeling off from the substrate and is an important consideration for the structural safety of high-speed laser cladding equipment. High-quality laser cladding equipment can achieve "metallurgical bonding" through parameter adjustment: the laser energy output by the equipment slightly melts the surface layer of the substrate, while the high-speed conveyed powder is completely melted. Atomic diffusion occurs in the molten pool to form a firm bond, which is different from the mechanical bonding of ordinary thermal spraying. For instance, the high-speed cladding equipment from Guosheng Laser can achieve a bonding strength of over 360MPa for steel-based and cast iron-based workpieces, meeting the requirements of heavy-duty working conditions such as shield machine cutters and engine blocks. During inspection, samples prepared by the equipment need to be evaluated with the assistance of a microhardness tester and verified through tensile tests to ensure that the bonding strength meets standards.

Dilution Rate: Key Parameter for Laser Cladding Equipment to Control Cladding Layer Composition

 

Dilution rate refers to the proportion of melted substrate metal in the cladding layer and directly affects the composition stability of the coating-excessively high dilution rate will deviate from the designed performance, while excessively low dilution rate may reduce bonding strength. High-speed laser cladding equipment precisely controls the dilution rate through three core parameters: adjusting the metal powder feeding rate of the equipment can reduce direct laser heating of the substrate; optimizing the laser power density (the ratio of power to spot size) prevents excessive melting of the substrate; and adapting the cladding speed shortens the interaction time between the laser and the substrate. Currently, leading industrial equipment such as Guosheng Laser's products can control the dilution rate to approximately 1%, much lower than that of traditional laser cladding equipment. This level can maximize the retention of the designed composition of the powder, ensuring stable performance of the cladding layer and making it suitable for precision processing scenarios such as molds and aerospace components.

Logic of Laser Equipment Cladding Parameter Debugging and Quality Compliance

In summary, the performance of high-speed laser cladding equipment requires reverse-adapting process parameters with the cladding layer inspection parameters as the target. In practical applications, it is necessary to first clarify the workpiece requirements (such as wear resistance and high-temperature resistance), then select metal powder in accordance with the equipment's characteristics; optimize porosity, hardness, bonding strength, and dilution rate by adjusting parameters such as the powder feeding speed, laser power, and cladding speed of the equipment; and finally ensure that all inspection parameters comply with industry standards to meet the usage requirements of different fields such as mining, aerospace, and machinery. In the future, with the intelligent upgrading of laser cladding equipment, parameter debugging will become more precise, further promoting the improvement of cladding layer quality and industrial application efficiency.