Laser cladding, also called laser metal deposition, is a technique for adding a material to the surface of another. The laser cladding process involves feeding a stream of metallic powder or wire into a melt pool generated by a laser beam as it scans across the target surface, depositing a coating of the chosen material. The process creates a mechanical bond between the base material and the deposited layer.
As a high precision and flexible process, laser cladding allows for the accurate and selective deposition of materials with just aminimal heat input into the underlying substrate. It allows for surface property improvements such as better wear resistance. Although the laser provides a high power heat source, the exposure time is short, which leads to fast solidification and cooling times.
Laser cladding delivers a metallurgically bonded layer that is tougher than that achieved with thermal spray and less dangerous to health than hard chromium plating. In addition, because the material gradient can be designed at the microstructural level, clad materials can be tailored to provide functional performance for specific applications.
Laser Cladding Types
Types of laser cladding process include conventional, large spot / high power, Extreme High-Speed Laser Application (EHLA) / high speed, internal bore, and 3D freeform. Each of these methods has its own variation on the process, such as with EHLA, where the powder is fed into the beam above the substrate and the relatively low heat input creates a narrow heat affected zone.
Advantages
Laser cladding provides several advantages over traditional coating methods, including the ability to use a wide choice of materials, precise deposition rates, good mechanical properties with little or no porosity, minimal substrate distortion, reduced production times and improved thermal control with laser power modulation.
Materials
Laser cladding can be performed with a variety of metals including aluminium alloys (Al-(Mg)-Si), cobalt alloys (Co, C, Cr, W), copper alloys, nickel self-fluxing alloys (Ni-Cr-B-Si), stainless steels (Fe, Cr, Ni), super alloys (Ni, Co, Mo, Cr, Si), titanium alloys, tool steels (Fe, C, Cr, V), MMC including carbides (WC, TiC, CBN), and nano additive alloys (oxide dispersion strengthened alloys).
Applications
Laser cladding has found uses in a wide range of applications, from manufacture to surface enhancement and repair. Example applications include cutting tools, where laser clad materials are used to protect blades and other cutting tools from wear and corrosion, with different levels of coating thickness being used according to requirements. Laser cladding can also provide wear and corrosion resistance for drilling tools and heat exchangers.