# Surface mechanical attrition treatment (SMAT) of steel Nano microstructure on surface of bulk sample

Deformation procedure in this material involves dislocation stages, mechanical twinning and the interactions of the mechanical twinning with the dislocations. The performance and properties of the SMAT treated layers were measured and tested by their thickness, hardness, fatigue, tensile strength and wear. The improved properties of the treated surface layer were attributed to the refinement of the strain induced grain. In this work, properties and microstructures of the SMAT treated layers of steel are reviewed
According to Hodgeson, Timokhina and Belad(Hodgson, Timokhina, &amp. Beladi, 2013), Surface mechanical attrition treatment (SMAT) is a new approach that has been developed for the treatment of mechanical surfaces. In this technique a number of balls to be treated are placed in a chamber and are vibrated at a very high frequency by a generator. The sample of the material to be treated is fixed at the upper side of the chamber. It is then repeatedly impacted by the flying balls in order for its surface to be heavily deformed plastically. Beside the conventional use of the plastically deformed surface, it hardens the surface and improves its fatigue and wears properties. SMAT has also been utilized, for example to activate a material surface before nitriding (Lu &amp. Lu, 2004. Z. B. Wang, Lu, &amp. Lu, 2006). SMAT creates multi-layered laminate composites due to its subsequent roll bonding (Caballero, Garcia-Mateo, &amp. Miller, 2014. Lin, J, Wang, &amp. Xue, 2006).
With all these practical potential applications, the micro-structural and metallurgical states of the deformed surfaces must be tailored in a reproducible manner and in different ways to form nanostructures with deep hardened zones (Roland, Retraint, Lu, &amp. Lu, 2006. Waltz, Retraint, Roos, &amp. P, 2009). In most cases material failure occur on surfaces such as corrosion, fretting fatigue, fatigue structure and wear (Seto &amp. Matsuda, 2013). These