SURFACE TEMPERATURE DIAGNOSIS OF CRACKS ORIGIN IN THE STRENGTH-DEFORMED METALS

2019;
: pp. 34-38
1
Lviv Polytechnic National University
2
Lviv Polytechnic National University, Ukraine
3
Ivano-Frankivskyi National Technical University of Oil and Gas
4
Ivano-Frankivskyi National Technical University of Oil and Gas

The results of theoretical studies on the correspondence of the numerical value of the critical density of internal energy to the value of the enthalpy of melting and the structural-energy analogy between the processes of mechanical destruction and melting  are  analyzed. The  physical  picture  of  the  distribution  of  temperature  field  formed  at  the  time  of  the  birth  defect, assuming considered previously investigated defect-free matter and assuming that the temperature redistribution in volume and at the surface  is uniform. Analytical and numerical analysis of  the heat wavefront arrival created by  the growing elemental defect depending  on  its depth  is  carried  out. The  obtained  results  of  the  experimental  researches with  the  help  of  the  created  control system allowed us  to approach  the question of prediction of  the depth of occurrence of micro defects arising as result of plastic deformation. The  calculations  have  been worked  out  and  practically  tested  for  future  applications with  the  system  of  external impulse contactless convection perturbation. 

As a result of studying the temperature-time dependences of the temperature distribution on opposite surfaces of the object of study, and depending on the depth of occurrence of the source of energy changes, the possibility of determining the location of the defect was experimentally determined, provided that the temperature sensors were located in the micro defects zone. For the creation of model quasi-point heating of a real research object corresponding to the model object, a non-contact “quasi-point” heat-convection  type heater was developed with  the  ability  to  form  a  temperature difference – up  to 100 K/mm. The  results of  the researches  are  the  basis  for  the  improvement  of  the  existing  system  of  control  of  the  development  of microcracks  in  stress-deformed metal structures.

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