Study On Smelting Technology Of Weathering Steel 09CuPTiRE-B

Weathering steel, also named atmosphere corrosion resistant steel, is a kind of low alloy high strength steel which contains a amount of alloyed elements, such as, Cu, P, Cr, Ti, Ni and so on. 09CuPTiRE-A steel is produced by WISCO and Chinese-characterized Cu-P-RE series weathering steel used for railway rolling stock. Its product qualities have reached advanced internal levels and been appointed by the railway ministry the steels which are made railway rolling stock.With the development of trains' increasing speed and lightweighting, the railway ministry has put forward a higher demand for 09CuPTiRE steel. Its strength must be improved from A grade to B grade except for superior corrosion resistant properties, this is to say, its yield strength and tensible strength are requested form 295MPa, 395MPa to 345MPa, 480MPa , respectively and excellent plasticity and toughness after enhancing strength.On the premise of no hugely changing the present production process, no increasing production cost and no altering the range of 09CuPTiRE-A steels' chemical composition, the cleanliness and homogeneity of the steel are improved by means of adjusting composition control object, playing the microalloyed elements and RE parts to the full, rigid control of inclusion's amount, size and form, ect.. Based on them the rolling and cooling process are optimized in order to fine grain microstructure are obtained, referring to strengthening and toughening mechanism of microalloyed steels. The function of precipitation and dislocation substructure strengthening are also important for improving strength and toughness in addition to fine grain strengthening.The industrial tests have been carried out in the No. 2 steelmaking plant of WISCO. The main elements' weight percent of test steels completely reach control object and their fluctuation is in a narrow allowable band. Average area percent of inclusion in steels is less than 0.1%, its diameter is less than 4 um with a large percent amount to 99%. The results show that the test steel's microstructure containing fine equiaxed ferrite+a little of acicular ferrite and pearlite has good mechanical properties and basically meets requirements of 09CuPTiRE-B steel with yield strength, impact energy at -40℃ and elongation more than 378MPa ,54J and 28%, respectively.