Research On Organization Structure And Controlling Of Mechanical Peeling Properties Of Iron Oxide Organization Of 72A Cord Steel Wire Rod

In order to improve the mechanical peeling performance of iron oxide which formed after spinning,the changes of structure and thickness of iron oxide were studied.According to Fe-O phase diagram,the isothermal experiment and proeutectoid or eutectoid transition of Fe-O experiment were designed under the condition of laboratory.The industrial test was carried out in the high speed wire rod production workshop,the final oxidized of iron oxide was studied by adjusting the stellmore temperature and cooling rate of each cooling section.Then the test wire rod were made into samples,the peeling property of iron oxide skin under different process conditions was tested by bending test and the optimum technological parameters were ascertained.There are the results of the experiment:?1?With the increase of oxidation temperature,the ratio of FeO thickness to total thickness was going up,the ratio of thickness to total thickness was wearing off.At high temperature,the iron oxide was mainly composed by FeO,with littel Fe₃O₄.With the decrease of oxidation temperature,the rate of generation of FeO was decreasing gradually,its content in iron oxide also gradually decreased.?2?At isothermal temperatures below 600?,according to different isothermal times,Fe3O4 pro-eutectoid structure and flaky?-Fe+Fe3O4 eutectoid structure appeared in FeO layer.According to the results of isothermal experiments,the C curve of FeO eutectoid transformation was plotted.?3?Thickness is a major factor in the peel ability of the oxide scale.With larger thickness of iron oxide,the peel size will be larger.In production the process should be adjusted in order to ensure the thickness of the iron oxide is at 12 to 13?m,which would achieve better mechanical peeling performance.The iron oxide get good peel ability when the FeO layer is better than 9?m.?4?Increasing the spinning temperature,the thickness will increase.Under the conditions allowed by the process,the spinning temperature should be 900⁹30?,the first cooling speed should be 6⁷.5?/s,and the second cold section should be 12²0?/s,and the coiling temperature is reduced below 200?.During the cooling process,coarse and sparse pre-eutectoid Fe₃O₄ phases should be avoided as much as possible.The cooling process of the on-site air cooling line is optimized.The thickness of the iron oxide scale of the optimized product has been stabilized at 12?m,and the produced iron oxide coating of the wire rod covers the complete matrix.After the bending test,the size of the stripping area of the sample is stable at 79mm.At the same time,the high carbon steel matrix structure and performance indicators all meet the requirements.