High-yield strength (450MPa), high-strength and weather-resistant steel plate and production method thereof

Abstract

The invention discloses a high-yield strength (450MPa), high-strength and weather-resistant steel plate produced by using the optimized composition design of single micro-alloyed Nb based on low-carbon manganese steel and using the TMCP (thermo-mechanical control process) based on the converter-CSP (compact strip production) shortened production process. The steel plate comprises the following components by mass percentage: 0.040% to 0.080% of C, 0.15% to 0.35% of Si, 1.20% to 1.40% of Mn, lower than or equal to 0.025% of P, lower than or equal to 0.008% of S, 0.015% to 0.035% of Nb, 0.25% to0.40% of Cu, 0.12% to 0.35% of Ni, 0.45% to 0.75% of Cr, 0.020% to 0.045% of Als, and Fe and unavoidable impurities in balancing amount. The production method comprises the following steps: molten iron pre-treating, converter smelting, LF (ladle furnace) refining, and CSP continuous casting and roller. The invention has the advantages of simple process, stable performance, good overall mechanical properties and lower cost.

Description

technical field [0001] The invention belongs to the technical field of iron and steel material manufacturing, and in particular relates to a high-strength weather-resistant steel plate with a yield strength of 450 MPa and a production method based on a converter-CSP short-flow process. Background technique [0002] In recent years, in order to meet the heavy load, fast transportation and safety of freight transportation, my country's railway freight car technology has developed towards the direction of large axle load and small self-weight. Lightweight design of freight car body is one of the effective ways to increase load and improve transportation capacity. At present, railway The main steel plate used for new trucks with a load of 70 tons and above is high-strength weathering steel with a yield strength of 450 MPa. As far as the structural strength of the vehicle is concerned, the high-strength weathering steel with a yield strength of 450 MPa can meet the requirements. D...

AI Technical Summary

Problems solved by technology

The disadvantages of this invention patent are: (1) Because Ti-containing steel is very sensitive to chemical composition and process parameters, it is easy to combine with non-metallic elements such as O, S, and N, resulting in large fluctuations in the properties of Ti-containing steel, and strict process control requirements At the same time, it is more difficult to control the addition of Ti in steel; (2) P content is higher, although it can improve the atmospheric corrosion resistance of steel, but P is easy to form segregation in steel, thereby improving the level of banded structure, which is harmful to steel plate cold Formability, low temperature impact toughness and weldability are unfavorable

[0005] The patent application number of Zhujiang Iron and Steel Co., Ltd. is 200810026086.X, which discloses a high-strength weathering steel with a yield strength of 600 MPa produced by an electric furnace-CSP process. The main technical scheme is: on the basis of low C and high manganese, add Nb, Ti composite microalloying increases strength through grain refinement and precipitation strengthening, adding Cu, Ni, and Cr improves atmospheric corrosion resistance, and obtains a high-strength and high-weathering steel with a yield strength of 600Mpa. The percentage content of the main elements is : C0.045~0.07%; Mn0.8~1.5%; Ti0.06~0.079%; Cu0.20~0.50%; Ni0.15~0.35%; Cr0.3~0.7%; Nb0.035~0.050%; P0.005~0.030; S0.002~0.008, the disadvantages of this invention mainly include three points: (1) high strength, but it is difficult to obtain good plastic toughness matching with strength; (2) adding Nb, Ti composite microalloy , wherein the lower limit of Nb weight percentage is 0.035%, the lower limit of Ti weight percentage is 0.06%, and the production cost is higher; (3) Ti-containing steel has the deficiencies described in the previous paragraph

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