The article deals with the influence of laser beams, which when acting on materials affect their surface. Depending on the intensity of exposure and the speed of displacement of the beam, due to the heating of the material and the subsequent cooling, there occurs the change in the pattern of the surface and of course to a change in the properties in the volume that was exposed to the temperature changes. For the tests the sintered material based on iron powder type Astaloy CrL and CrM containing 0.7% C was used. Results showed that by the appropriate combination of laser parameters it was be possible to obtain the same structures as by using the technology of "sinterhardening". Compared to sintered state, the hardness of the surface of a material CrL +0.7% C values increased from 248 to 911 -1000 and at material CrM +0.7% C values from 450 to 1043 -1100 HV 0.05, depending on the velocity of displacement of the beam. The same is true for the values of microhardness. Hardness values reflect the structural changes that occur in the material due to rapid heating and subsequent rapid cooling. The first tests of this technology demonstrated its high variability and the potentials of replacing classical procedures.Keywords: laser hardening, sintered material, structure, hardness IntroductionLaser hardening is one of the new technologies, which is currently widely used in the manufacture of machine parts. The principle of laser quenching consists in the rapid heating of the material surface by laser, short holding time at temperature followed by cooling, heat dissipation due to thermal conductivity of the material. A significant advantage of the heat treatment is its speed, quality and especially stable reproducibility. In addition, it provides low thermal load to the ambient material, minimum distortions, low surface oxidation and prevents formation of surface cracks. It is also possible to arrange for local hardening only at the desired location, to control the depth of hardening and the resulting hardness. The temperature is in many cases controlled on-line by a pyrometer directly integrated in the optics. Typical applications include local hardening of molds, tools, gears and racks, guide surfaces, parts of transmissions, shafts, cams and turbine blades and vanes [1][2][3][4][5]. Nowadays, when in the engineering practice, powder metallurgy product are increasingly promoted, knowing the possibilities of using this type of heat treatment at this type steels is quite real. In the actual powder metallurgy practice in connection with the development of steels for highly stressed components, such alloyed materials has been introduced, which following heat treatment by hardening are able to achieve the desired mechanical properties. In addition to conventional quenching, by some suitably alloyed materials, there are currently method in use

Chemical and heat treatment of steels of known technology increases the hardness and wear resistance and contact fatigue of machine parts. Compared to conventional gas nitriding, the technology of plasma nitriding provides several advantages (control layer thickness, velocity nitriding). This article describes the symptoms of contact-stress fatigue in sintered steel powder made by commercial company Höganäs, when type CrL in versions with addition of 0.3 and 0.7% C and CrM with addition of 0.3 %C were subjected to plasma nitriding under specified conditions. This paper briefly explains the impact that the plasma nitriding, causing resistance to contact fatigue effects on some mechanical properties as well as changes in the metallographicmicroscopic field.