P Hosseini Tehrani - Mechanical Dept, iran university of science and technology, narmak, tehran
S Hosseini Hashemi
K Khorshidi
S Alizadehnia

Tecjnological advances necessitate the use of material in increasing extreme and aggressive conditions, such as corrosive atmospheres and abrasive wear situations. Laser hardening is widely used to improve the mechanical properties of highly stressed material is, the pulse duration is of the order of nano-second therefore thremoelastoplastic shock waves produce and propagate through the domain. The pulse duration is of the order of the characteristic time for heat to diffuse across the layer thickness, and hence axial heat conduction can not be neglected. Temperature, displacement and stress due to thermal shock are calculated. It is shown heat compressive residual stress may be produced collinear to the surface, which may improve is surface hardness and fatigue life, In this study we obtain stress and temperature thremoelastoplastic fields in thin layer under thermal and mechnical shock due to laser surface hardening. The Laplace transform technique is used. The Durbin method is employed for the inversion of the Laplace transforms. The Boundary Element Method (BEM) is employed for the stress and temperature distribution are given and illustrated graphically for each problem.

Laser Hardening, Engine parts, Shock Wave, Thermoplasticity