The Effect of Laser Processing Modes on the Change in the Structure and Mechanical Properties of the Surface Layer of Parts Made of 30XGSA Steel

The purpose of the work was to study the influence of laser processing modes (cutting, cleaning, grinding) on the change in the structure and mechanical properties of the surface layer of parts made of 30XGSA steel obtained by various methods. 

Methods of research. As an object of study, we chose medium-alloyed structural steel grade 30KhGSA in cast (rod Ø8 mm) and hot-rolled (sheet 6 mm thick) states. To study the effect of laser cleaning on the change in the structure and mechanical properties of machine parts using laser cutting, special samples were made.

Results. It has been established that laser cleaning of hot-rolled steel grade 30KhGSA without preliminary surface treatment (in particular, mechanical grinding) leads to the formation of microcracks. Regularities of changes in the structure of the gas-laser thermal impact zone after laser cleaning are revealed. It is shown that laser surface cleaning leads to the formation of a denser structure and an increase in microhardness, which occurs due to the diffusion of carbon to the surface layers of the part. It has been established that the nature of the change in microhardness for all studied samples of 30KhGSA steel in the cast and hot-rolled states is the same: the highest values are achieved near the surface of gas-laser treatment and are, for example, for cast steel 250-320 HV, which is 1,3-1,6 times greater than the initial microhardness (194 HV), and for hot-rolled steel 247-273 HV, which is 1,5-1,6 times greater than the initial microhardness (168 HV). Thus, a hardened layer with increased wear resistance is formed on the surface of the part after gas-laser processing (laser cleaning and laser polishing).

Conclusion.The results obtained can be used in the creation of resource-saving material processing processes.

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