Study On 520-750MPa Hot Rolled And Wear Resistant Steel In 2250mm Production Line

With the depletion of natural resources,energy consumption has become an important indicator of concern for various companies.Achieve the purpose of reducing costs and increasing efficiency,automobiles,steel structural parts,etc.continue to propose lightweight targets,reduce equipment internal consumption.At the same time,higher requirements are placed on the strength of steel,and low-carbon microalloyed high-strength steel sheets have received widespread attention.This paper combines the actual situation of the existing hot rolled sheet production process of Baotou Steel.Design and develop 520~750MPa hot-rolled wear-resistant steel plate for Baotou Steel,using computer software JMatPro combined with experimental research,which fills the product specifications of Baotou Steel's existing hot-rolled steel plate.The chemical composition design of the three grades of 520MPa~750MPa is determined,and the subject includes three grades of BT520 JJ,BT590GJ and BT750 GJ.BT520JJ grade adopts Mn-Ti-Cu microalloy combination design,BT590 GJ grade takes Mn-Ti-Nb microalloy combination design and BT750 GJ grade adopts Mn-Ti-Cr-Mo-V microalloy combination design.Welding research has been carried out on the above three grades of steel grades,and the microalloyed steel plate welding should select the welding process of “equal matching” or “super strong matching”,among them,the BT520 JJ grade steel plate has been industrialized.And the KR method is used for hot metal pretreatment.The molten iron content of molten iron should be ?0.01%,and the tapping temperature should be ?1620?.LF refining is based on the composition and temperature of the converter steel to carry out slag desulfurization,adding alloy to adjust the composition,and the temperature satisfies the continuous casting process.The liquidus temperature of continuous casting is 1513?,the superheat degree is 25~40 ?,and the average pulling speed is 0.8~1.3 m/min.The billet is heated in three stages,and when the heating temperature is 1080 ?,thetemperature section is quickly crossed to prevent the copper surface from collecting and causing surface crack of the continuous casting blank,the temperature of the furnace is1220 ? ± 15 ?,the soaking time is ? 30 min.Finish rolling rolling temperature960~1040 °C,finishing rolling temperature 870~880 ? ± 15 ?,crimping temperature610~620?±15?.The above rolling process was optimized,and analysis showed that lowering the crimping temperature can increase the residual strength of the tensile strength and elongation of the BT520 JJ steel plate.The crimping temperature is controlled at a lower of 600-590 ?,which makes the amount of pearlite structure increases in rolled microstructure.Increase the degree of subcooling pearlite structure of the sheet is more refined,BT520 JJ tensile strength increased by 10 MPa,elongation increased by 4%.Through the research in this paper,the use of computer software to assist component design not only saves research and development costs,but also shortens the research and development cycle.The successful development of 520MPa~750MPa grade wear-resistant steel plate enriches the product types of Baotou Steel low-alloy high-strength steel plate and enhances the product type.The market competitiveness in this field has also accumulated practical production experience for other steel companies to develop low-carbon microalloy high-strength steel plate new products.The goal is to save energy and increase productivity.During quenching,to get the whole pearlite structure and good flatness,cooling intensity on rail's different parts is changed in different time.