**1. Introduction**

Advanced industrial applications require materials with special surface properties such as high corrosion and wear resistance and hardness. Alloys possessing these properties are usually very expensive and their utilization drastically increases the cost of the parts. On the other hand, failure or degradation of engineering components due to mechanical and chemical/electrochemical interaction with the surrounding environment is most likely to initiate at the surface because the intensity of external stress and environmental attack are often highest at the surface.

The engineering solution to prevent or minimize such surface region of a component through a procedure known as surface engineering. Conventionally practiced surface engineering techniques like carburizing, nitriding, etc. are often material specific, time/energy/manpower intensive and lacking in precision.

Among the surface engineering techniques, a relatively new and attractive method is laser surface treatment. In other words, laser surface treatment offers an excellent scope for tailoring the surface microstructure and/or composition of a component and proves superior to conventionally surface engineering.

For most engineering application, the laser, in simple terms, can be regarded as a device for producing a finely controllable energy beam, which, in contact with a material, generates considerable heat. The basic physics of laser surface treatment is simply heat generation by laser interaction with the surface of an absorbing material and subsequent cooling either by heat conduction into the interior, or by thermal reradiation at high temperatures from the surface of the material. Various laser surface treatment methods that are currently available are shown in figure 1.
