Khaskin V. Scientific and technological basis of laser and hybrid welding processes and surface modification of metal products

The thesis is devoted to developing the scientific basis of deposition and processing of metal surfaces using laser light through the study of thermal, physical and metallurgical phenomena that accompany these processes, building on this basis, the generalized calculation and the experimental procedure of the provisional assessment and selection of parameters of technological regimes, which provide the necessary quality and functional characteristics of the workpieces. The paper analyzes the current state of development of laser technology in the field of engineering surfaces and shows the lack of systematic scientific basis of laser and hybrid welding and modification. This makes it impossible to develop new technological approaches and expand the range of problems solved by methods of laser surface treatment. To overcome this problem a number of studies. Studies of thermal processes of laser and hybrid treatment of metal surfaces allowed on the basis of power-distribution circuit at steady state to create a mathematical model with which to determine the parameters of the processing by optimizing the temperature distribution in the depth of "weld (processed) layer - base metal" according to the criterion of minimizing heat input. Studies of physical and metallurgical characteristics of the processes of surfacing and modification of metal surfaces allowed by optimizing the thermal cycles to reduce residual stress of processed layers, leading to the minimization of cracking, as well as establish criteria for elimination of internal pores and delamination of coatings. The influence of laser technology and hybrid processing on the quality of the metal surface has provided the framework for action on enforcement and monitoring of this parameter. Found that hybrid processes that substantially reduce the level of residual stresses and coefficient of cracking in the clad (doped) layers, reduction of allowance for finish machining a few times, and also reduce the coefficient of friction of treated surfaces with a simultaneous increase in their resistance to scoring. A generalized computational-experimental procedure for selecting parameters of the technological regime for the processes of laser and hybrid (combined) surfacing and modification of metallic surfaces. Using this technique developed a number of laser surface engineering.