400-500MPa耐大气腐蚀钢工艺及性能研究

400-500MPa耐大气腐蚀钢工艺及性能研究
　　Weathering steel is made by alloying with certain elements which is one kind of low alloy high strength steel with good corrosion resistance. It is widely used in steel structures such as train cars, bridges and buildings. As a high effective steel product, It has been being the focus of development of products and corrosion research. The new generation weathering steels should meet the development requirement of higher-speed and heavier-load of railway Ball Neodymium Magnets transportation in our country. Therefore, the properties such as high strength, high toughness, high ductility, low yield ratio, low toughness-brittleness transformation temperature (TTT), obvious yield point, good weldability and corrosion resistance should be included in the development target to meet the requirement of manufacture, loading capacity and safety during uninterrupted movement of train cars.The article is dealing with such topics as how to ensure atmospheric corrosion resistance, to realize high strength and further improve toughness and ductility, as well as to improve weldability. Correspond measures are put forward by detail analysis. Optical microstructure, mechanical properties, toughness-brittleness transformation temperature, aging-resistance, weldability, corrosion resistance were investigated. The results show that the designed chemical compositions and process of the Pangang-developed 400Mpa, 450Mpa and 500Mpa grade Cu-P-Cr-Ni and rare earth treated Cu-Cr-Ni high strength weathering hot-rolled steel plate for train cars are rational. The results show that the complex properties of experimental steels are good.
　　These steels can be put into stable commercial production.The experimental steels were VN microalloyed and treated with microalloying Ti. The microstructure of V-Ti-N steels is similar to V-Ti steels, consisting of polygonal ferrite and pearlite. The effect of [N] in the steels results in on one hand, more precipitated vanadium and on the other hand, http://www.chinamagnets.biz/ makes the precipitates of vanadium finer and denser. Therefore, more dense and fine precipitates can be found in V-Ti-N steels than in V-Ti steels. The precipitated vanadium can also be affected obviously by the Ti content in steels. However, The precipitated vanadium increases with [N*] content in steels. It is very important for thestability of strength and the enhancement of strength of V-Ti-N steels to suitably lower the Ti content in steels and stably control it. The experimental steels exhibit lower toughness-brittleness transformation temperature and the aging caused by free nitrogen can be neglected because the enhancement of nitrogen results in more precipitates of vanadium and the free nitrogen content in steels is kept at lower level. It also shows that little Ti adding in steels with lower Mn content and adjustment of the coiling temperature can elevetate weldability and gain obvious yield point. Forthermore, the better range of RE content is obtained. It is effective for purifying steels, modifing inclusion and enhancing microalloying effect, the direct impact values of steels are improved.The technology stragy of high strength weathering steels at Pangang steel is ascertained through experimental work. The study offers the essential technical surport for the further development of products.