Laser Surface Modification, Machining and Nanoparticle Formation

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**Chapter 4**

**Abstract**

**1. Introduction**

Materials

*and Durairaj Raj Kumar*

Laser Surface Modification of

The metallic materials such as steel, iron, titanium and nickel alloys etc., are extensively used in the automobile, marine, biomedical, aerospace, chemical industry and power generation sector. However, the poor surface properties restricted their wide usage in many applications. Therefore, the surface properties need to be enhanced through novel treatments without affecting the bulk. In recent years, laser surface modification attracts more due to their inherent properties. The laser based surface altering process is appropriate to modify the metallic surfaces in terms of their flexibility, simple operation and process economy. Laser surface modification includes; surface hardening, melting, alloying, cladding and texturing. Thus, from a process engineering, metallurgical reasons and tribologist view point, the laser

In the 20th century, Laser surface alteration played a major role in enhancing the material surface properties. Among the number of ways to enhance the material properties, laser based surface alterations are used to enhance a better physical property in the machined surface and improved the component performance. The high power Neodymium Yttrium-Aluminum-Garnet (Nd: YAG) laser, carbon-dioxide (CO2) laser and excimer lasers are used to perform the laser surface treatment which is expensive, popular and operate at pulsed mode or continuous wave mode. These lasers are used to heat the near-surface area of the finished components for enhancing the properties. The laser surface modifications have the ability to control the amount of heat energy to work material with high directionality. The purpose of a surface hardening by laser is to improve the component wear properties. The laser surface hardening is defined as the heat energy from the laser beam that directly heated the component surface at a very short interval period without melting the work material. The heat input to the component surface is the reason for creating the tough and fine-grained structure in the hardened surface. The risk of crack forming is very low due to the self-quenching process. The laser surface melting (LSM) is heated to its melting point through a high power laser beam and rapidly solidified. The aim of LSM is to refine the surface microstructure, homogenization of composition, dissolution of precipitates. The LSM is also used to improve the corrosion resistance of steel and iron. The minimization of intergranular corrosion

surface modification process can be recognized as an important topic.

**Keywords:** laser hardening, melting, alloying, cladding and texturing

*Natarajan Jeyaprakash, Che-Hua Yang* 
