In order to improve the accuracy of image edge detection.A spline interpolation sub pixel edge detection method based on improved morphological gradient is proposed in the thesis.Firstly,using improved morphological gradient filter operator for image coarse positioning;Then,the cubic spline interpolation method is carried out for pixel-level edge of the image interpolation so that the image edge locates in sub-pixel level.Have a simulation experiment to improved methods by Matlab, results show that the improved method can accurately detect the edge of the image, edge detection is fine, the precision of positioning is hight and the result of detection is good.

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Ferritic nitrocarburizing is being proposed as an alternative to gas carbonitriding to improve the surface characteristics of SAE 1010 plain carbon steel automotive components without producing unacceptable part distortion. Navy C-rings are specially designed specimens for the evaluation of the distortion (size and shape) that result from any heat treatment process. In this study, gas ferritic nitrocarburizing and nitrogen cooling was used to heat treat Navy C-ring specimens of varying thicknesses (2.8 mm-19.05 mm) at temperatures ranging from 510°C to 595°C. For each combination of part thickness and heat treatment temperature, the following parameters were evaluated: size and shape distortion; XRD and OM (optical microscopy) to characterize the nature of the nitride layers formed at the surface; X-ray determination of the residual stresses in the nitride surface layers.The various combinations of nitrocarburizing temperature and time resulted in an expansion of the OD (Outside Diameter) dimension and a small deterioration in flatness. The ID (Inside Diameter) changed from a small expansion (+0.02%) for the thickest specimens (19.05 mm) to a small contraction (-0.02%) for the thinnest specimens (2.8 mm). The gap tends to close up as the thickness decreases from the thickest to the thinnest specimens. Microstructural differences were found in the nitrided layers formed at the different heat treatment temperatures. The residual stresses in the outer ε-nitride layers (Fe 3 N) were typically tensile. On the basis of these results, preliminary recommendations are made as to heat treatment parameters to lower distortion.

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Carbonitriding is a metallurgical surface modification technique that is widely used in the automotive industry to increase surface hardness and wear resistance. Given the problems associated with carbonitriding, such as dimensional distortion, oxidation and non-uniform surface hardness, nitrocarburizing has been proposed as an alternative heat treatment method to improve the surface characteristics. The major advantages of ferritic nitrocarburizing are the minimal dimensional changes and distortion due to the low process temperature at which no phase transformations occur. This increases productivity and product quality, and decreases costs. The focus of this study was to determine the effects of carbonitriding and ferritic nitrocarburizing processes on the dimensional changes and residual stresses in a steel used for automotive applications. Navy C-ring specimens and prototype stamped parts made from SAE 1010 plain carbon steel were used in the testing. Gas, vacuum and ion ferritic nitrocarburizing processes with different heat treatment parameters were investigated. X-ray diffraction techniques were used for the residual stresses evaluation and surface phase analysis of the specimens.