Generally speaking, image analysis is picking-up useful data and information from image. Image segmentation is a important method in image analysis, in our paper, on the basis of summarizing predecessor's theory and experiment, think about practical application at the same time, we adopt a method of image segmentation based on fringe pick-up namely line scan space band-pass filter. This method could decrease information amount consumedly, and provide enough preparative for automatic recognition of system after image segmentation.
The method adding electromagnetic field during laser heat treatment is a new heat treatment method that expend application expansion of laser heat treatment. In this paper, based on thermal non-elasticity, principle of metal phase transformation, deformation thermodynamics and theory of electromagnetic field and using the internal variable method of continuous medium mechanics, the heat conduction equation with magnetic-field phase transformation during laser heat treatment has been inferred. The equation and its theoretical method is the basis to study the theory and experiment of laser magnetic quenching and also the basis to study further on the material structure distribution and properties. And also by means of the equation, has the numerical analysis on temperature field in the course of laser magnetic quenching been in progress.
According to phase transformation theory of steel, thermal elastoplastic theory and laser phase transformation characteristic, conditions of austenitic transformation in course of heating and martensitic transformation during cooling, extensive equation of martensitic transformation quantity and nonlinear equations of temperature field and stress field are put forward in this paper. Also effect of applied stress on temperature field, stress field and phase transformation course is studied.
In this paper, the temperature field influencing by applied stress during laser phase transformation hardening is analyzed by finite element method, according to the principle of heat conduction, phase transformation and thermal elasto-plastic mechanics. The function and variation theorem of the tmperature field influencing by applied stress during laser phase transformation hardening are established. Meanwhile, its FEM basic equations with triangle element are presented.
In this paper, according to the theories of phase transformation, thermal elastoplastic and characteristics of laser quenching, after analyzing the process of isothermal phase transformation and variable temperature phase transformation, heating austenite transformation and cooling martensite phase transformation, and considering the properties of CCT curve, a mathematical model of martensite phase transformation has been obtained and nonlinear heat conduction equation considering the effect of the thermal physical property coefficients and phase transformation have been given, which reflects the hybrid method of F.E.M. (Finite Element Method) and F.D.M. (Finite Differential Method), the transient temperature field during laser quenching on plates and distribution of phase transformation organization have been calculated and analyzed. When calculating the temperature, distribution of austenite and martensite organization and laser hardening region can be calculated too. Comparing the results of calculation with that of experiment, we can make conclusion that our theoretic analysis is valuable for practice and physical coefficients during calculation is significant to the study of laser quenching technology and theory about predicting the material properties.
This paper is based on theory of extended Landau phase transformation, consider achievement of A. F. Devenshire and F. Falk et al, and combines with characteristics of martensitic transformation, the research of effect of applied stress on martensitic transformation during course of laser phase transformation hardening, has been in progress, and a functional analysis expression of Gibbs free energy, which applies to describe the concrete problem, has put forward and discussed. In the paper, the various law of laser phase transformation hardening layer of 45# steel under action of applied stress is studied. The conclusion shows that theoretical analysis are in accord with experimental results.
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