The Research Of The Organizational Performance And The Corrosion Resistant Performance Impact Of Ca-Cu-P In Carbon Steel

As a kind of efficient steel, weathering steel has been used for the development of varieties and hot research of atmospheric corrosion steel. With the rapid development of our national economy, weathering steel with higher corrosion resistance, higher strength and low cost needs to be developed. Because Ca and Re both have the role of non-metallic inclusion modification and purifying liquid steel, but Ca has the obvious price advantage compared with Re. Therefore, in this paper Ca is used instead of Re to add to weathering steel. The effect of Ca on non metallic inclusion,microstructure, mechanical properties and corrosion resistance of Cu-P weathering steel has been deeply researched.The effect of Ca on inclusion in weathering steel has been studied through the methods of metallographic microscope, image analysis software and scanning electron microscope. The conclusion is obtained that non-metallic inclusions in the steel can be changed to composite inclusions containing Ca-Al-Mn-O-S through calcium modification. With the increase of the content of Ca, the inclusions tend to distribute more uniform. The size of 40% inclusion is smaller than 2μm and the size of 96% inclusion is smaller than 5μm in the weathering steel whose Ca content is0.0029%. So Ca changes the size and distribution of the inclusions in steel to reduce its damage to the steel property. Such small inclusions even can change into the beneficial factor of improving the quality of the steel.Through the methods of laboratory cycle accelerated corrosion experiment,weightlessness experiment, scanning electron microscope and X ray diffraction, a comparative study have been done between Ca-Cu-P weathering steel and carbon steel Q345. The conclusion is obtained that Cu-P weathering steel corrosion resistance is superior to that of plain carbon steel, weathering steel corrosion resistance of Cu-P weathering steel with Ca is obviously better than that without Ca.The steel whose content of Ca is 0.0014% has the lowest corrosion rate in various corrosive stages. The corrosion rate of the weathering steel containing 0.0029% Ca decreased faster than other steels, so its rust layer is also stabilized very quickly.Because the rust layer of the weathering steels containing Ca is dense and cracks less,and the protective rust thickness increased significantly, it has better base protection ability. The amount of α-FeOOH in corrosion products is very high and the amount of Fe3O4 is little in the weathering steel whose Ca content is 0.0029%, so Ca alloy in weathering steels can promote the formation of α-Fe OOH in the rust layer. The Ca element of weathering steel enriched mainly in the external of the rust layer,especially in the cracks of the rust layer, while Ca element can promote the enrichment of Cu in the rust layer evenly, which is favorable for the formation of protective rust layer...