The Theoretical And Experimental Study Of Q235 Steel Strip Surface Oxide Scales Fracture

Oxide scale on the hot rolled material is a key factor effect the cold rolling which must be removed. The current method is removed by pickling, but the malpractice of pickling is obvious, such as the environmental pollution, the surface of the "Black Belt", the matrix is ??easy to produce "hydrogen embrittlement" phenomenon and the waste acid treatment. So in the future it will be replaced by the green mechanical methods. The mechanical method of removing oxide scale includes repeated bending method, shot and blast method,but it difficult to replace pickling descaling because of low efficiency, greater roughness and other factors. In order to guide the development and application of new technologies, the paper observed morphology, thickness and the size and quantity of the hole of oxide scale on Q235 steel surface by an ultra deep microscope, SEM, EDS and other equipment. We also study the oxide scale failure mechanism and analysis the fracture states of oxide scale during bending of the material combined with ANSYS / ls- prepost software. The main contents of this paper are as follows:1. Oxide scale fracture failure mechanism was analyzed, studying the important parameters that affect the failure of oxide scale, such as the thickness and the hole of oxide scale. The relations about the hole size in the oxide scale varying with the thickness was determined, improving oxide fracture failure theory.2. Oxide scale was bent, analyzing the factors that influencing the oxide scale load- displacement curve. The critical strain of oxide scale during the bending process was calculated, and the interface roughness value between oxide / metal substrate was obtained by means of compared the theoretical critical strain and the actual critical strain of the oxide scale failure.3. Combined with the oxide scale failure theory, the process of oxide scales fracture was analyzed by FEM, analyzing the variation of the mechanicalproperties in the oxide scale fracture process. Besides, we considered the quality of the strip surface, looking for the high efficient position of remove oxide scale and guiding the production practice.Some parameters was obtained through the experiment, completing oxide burst failure theory, combining with the finite element simulation study oxide scale in the process of bending fracture, providing a theoretical guidance for a new descaling system.