Analysis of transformation of subsurface layers structure of steels and their influences on process of hardening with AMD-methods
Steel have a wide circulation in military, industrial, scientific applications. One of important problems is the problem of calculation of control of structure and properties steels, especially their near-surface layers. Her decision is connected with an operating control of structure and strength characteristics. Therefore, in the real work, object of researches - steel of various brands, structure and properties of their near-surface layers. The purpose of researches - influence of parameters of external impacts on strength characteristics of near-surface layers steels, to the subjected processes of cementation and nitriding. For achievement of a goal it is offered to use innovative control devices of structure and properties of materials - AMD-methods. The main method is the method V ( Z )-curves, based on obtaining characteristic interferential dependences of an output signal of V from distance Z lens object in acoustic waves. Measurement of parameters V ( Z )-curves allows to count values of speeds of surface acoustic waves ( v<sub>R</sub> ) and to estimate the level of their attenuation in samples (D V / V %). These characteristics provide calculation of strength parameters and parameters of plasticity of materials. Application of the offered techniques has allowed to receive series V ( Z )-curves for a row staly, to calculate for concrete brands of value of speeds of superficial acoustic waves ( v<sub>R</sub> ) and levels of their attenuation in samples (D V / V %). Depths of diffusive layers in the steels at cementation and nitriding have been determined. Estimates of values of coefficients of diffusion for the studied materials are carried out. By means of AMD-methods elastic modules of materials and speed surfactant in them which comparison with tabular values has shown high extent of coincidence are calculated.