Surface alloying

Menu :

• Laser principle
• Laser sources
• Applications
  • Cutting
  • Metallic welding
  • Plastic welding
  • Soldering
  • Brazing
  • Marking, engraving
  • Cleaning and surface preparation
  • Cladding
  • Surface alloying
  • Laser assisted machining
  • Laser machining

Principle :

Surface alloying consists in altering the chemical composition at the surface of a material by simultaneous remelting with an additive element. This additive element can be :

• a coating with controlled thickness
• insulation of a reactive or organic-metallic gas on the melting pool
• injection of alloying powder in the melting pool

The alloying process, very close to the remelting, uses similar treatment conditions (105 W/cm2 ; 100 ms). The homogeneity of the alloying is made by convective mixing in the melting pool and by the multiplication of the tracks due to their large width.

Characteristics

Laser surface alloying is commonly used to enhance locally its properties. Its advantages are as follows:

• Costs effective: the process substitutes to the massive purchase of expensive or hard to use materials
• Metallurgy: it offers new solutions by making alloys, unique in composition and microstructures
• Geometry : low distortion, high precision and flexible motion

Despite its great metallurgical interest, the use of this technique is limited in the industry because it requires two stages and a reduced surface overlapping due to the conditions of alloying homogeneity.

Top and side view of a cladding

Industrial examples

Surface alloying is still in a development stage as show the different studies that are in progress in the laboratories. There are many possibilities of applications like the enhancement of light alloys surface characteristics. The main brake for its industrialization is due to the costs of laser sources (CO2 and Nd-YAG) but the use of diode laser makes things different.