Laser Cladding Applications and Advantages as a Repair Coating Technology

Turkchem 24 May 2021 65 4 dk okuma

TURKCHEM

Laser cladding technology continues to establish itself in industry as a rapidly developing repair filling or coating application. As an alternative to welded filling (MIG, TIG, PTA) applications, it provides advantages in significant repair applications due to lower heat input to the substrate material and higher deposition rate. In welded fillings, high heat input causes internal stresses, distortions and grain coarsening in heat-affected zones, resulting in weakened mechanical properties and crack formation. Powders of mostly metallic character in a specific size range and specific forms are melted with laser beam and deposited on the component surface, allowing casting defects, machining errors, insufficient filling and wear-related errors to be corrected by accumulating powder material to achieve desired tolerances, or a protective hard and corrosion-resistant layer can be created on the surface to extend the component's service life. The laser cladding process is shown schematically in the diagram below. A laser beam of appropriate power, protective gas (Ar), powder (or wire) supply unit providing powder (wire) flow and carrier gas flow, water cooling system at the spray nozzle and the workpiece being processed can be seen. The laser beam is directed at the surface creating a melt pool. As powder flow continues, the powders accumulating in the melt pool continue to melt, and with the relative movement of the nozzle at a specific speed, coating layers and filling are formed on the surface layer by layer. Metallurgically, a strong bond and adhesion forms between the clad layer and the substrate. Penetration into the substrate is less than in weld fillings. This reduces the risk of distortion and crack formation. Process parameters: Laser type, laser intensity, spray distance, gas flow rate, laser power, powder feed rate, substrate temperature, surface condition, substrate hardness, substrate thermal properties, particle size distribution and form of powder materials, average particle size. Laser cladding technology produces successful results in numerous applications both as an additive manufacturing method and as a coating technology and additive manufacturing technology due to its ability to create a protective, performance-enhancing layer on the surface. Laser cladding technology creates a metallurgical bond with the substrate and exhibits much higher bond strength compared to thermal spray coatings. Due to providing lower heat input compared to welding methods, it reduces distortion risk. For this reason, it is highly suitable for repair coatings. Particularly in components operating under aggressive working conditions, the accumulation of suitable material by laser on the component surface against section losses caused by wear and corrosion protects the component and increases its durability. Component replacement costs and maintenance costs can be reduced with laser cladding. Due to the absence of coating thickness limitations, technical drawing section tolerances can be easily achieved. Laser cladding method can be used in turbine blade repair, wear surface repair of hydraulic rods and cranks, surface strength enhancement and repair of high-strength aluminum alloy components. [caption id="attachment_125245" align="aligncenter"] Turbine blade repair[/caption] [caption id="attachment_125246" align="aligncenter"] Laser cladding in repair of worn components[/caption] [caption id="attachment_125247" align="aligncenter"] Laser cladding application on aluminum component surfaces[/caption] [caption id="attachment_125248" align="aligncenter"] Laser cladding application on aluminum component surfaces[/caption] Materials Used in Laser Cladding • Tool steels (Fe, C, Cr, V) • Stainless steel materials (Fe, Cr, Ni) • Cobalt alloys (stellites: Co, C, Cr, W) • Superalloys (Ni, Co, Mo, Cr, Si) • Nickel-based self-fluxing materials (Ni-Cr-BSi) • Titanium alloys (Ti, Al, V) • Aluminum alloys (Al-(Mg)-Si) • Copper alloys

Application Advantages of Laser Cladding

Low heat input. • Advantage of application to localized and narrow areas. • No geometric limitations. • Wide material selection options (nickel-based, aluminum-based, iron-based, cobalt-based powders) available. • No coating thickness limitation. • Fast powder deposition capability. • Robotic control advantage (can be integrated with CNC, CAM programs). • Heat-affected zone is small and narrow. • Low penetration into substrate. • High bond strength achieved through metallurgical bonding. • High wear, corrosion and impact resistance achievable. • High temperature-resistant coatings producible. • Dense, porosity-free layer deposition capability. • Machinability possible. • Applicability to both internal (pipe interior, channels, etc.) and external surfaces.

Repair Application Areas of Laser Cladding

Mining equipment, • Turbine components, • Hydraulic rods, shafts, • Brake discs, • Gear systems, • Agricultural equipment, • Wire drawing process components, • Forming dies, • Defense industry components, • Boilers, • Boiler tubes, • Crank components, • Bearings, • Pump components, etc.

Laser cladding can be applied for repair purposes in multipurpose industrial applications. The quality of the formed layer determines the component's service life and performance. It appears that in the future it will be widely used in repair, filling and additive manufacturing applications. The laser cladding systems and equipment market is experiencing rapid development. In the sector holding an 18M$ market share, Europe holds 41% of the market. The annual growth rate is at 2.69%. With the inclusion of repair application specifications in international standards, an increase in usage potential is expected.