Fracture of Laser-Hardened Cylindrical Rods Caused by Torsion and Tension

We study the influence of the direction of motion of a laser beam over the surface of a cylindrical rod in the process of hardening on its strength and character of fracture caused by torsion. The process of hardening of specimens made of 45 steel performed in the tangential direction along a spiral and in the longitudinal direction along the generatrix with different degrees of overlapping of laser tracks results in the formation of an anisotropic structure, which strongly affects the investigated characteristics. The best results are obtained in the case where the direction of deformation of the rods coincides with the direction of screwing of a nut on a right-hand screw and the material of hardened tracks works in compression. In the case of torsion in the opposite direction, the material of hardened tracks works in tension and the strength of the specimens slightly increases. At the same time, their plasticity abruptly decreases.