Production method of high straightness super-strength steel

Abstract

The invention discloses a production method of high straightness super-strength steel. A steel production process route comprises the following steps: pretreatment of molten iron, converter smelting,LF external refining, VD vacuum treatment, continuous casting, heating, rolling, straightening, quenching, tempering, finishing, performance inspection, and flaw detection. The high straightness super-strength steel is characterized by being prepared from the following chemical components in percentage: 0.15 to 0.20 percent of C, 0.15 to 0.35 percent of Si, 1.0 to 1.50 percent of Mn, smaller thanor equal to 0.012 percent of P, smaller than or equal to 0.003 percent of S, 0.010 to 0.030 percent of Nb, 0.015 to 0.040 percent of V, 0.010 to 0.025 percent of Ti, 0.020 to 0.045 percent of Als, 0.040 to 0.60 percent of Cr, 0.10 to 0.30 percent of Mo, 0.20 to 0.50 percent of Ni, 0.0008 to 0.0025 percent of B, smaller than or equal to 0.60 percent of CEV and the balance of Fe and inevitable impurities. The super-strength steel has the characteristics that the production thickness is 6 to 25 mm, the width is 1,500 to 3,800 mm, the yield strength of a steel plate is greater than or equal to 1,100 MPa, the tensile strength is greater than or equal to 1,200 MPa, the elongation percentage is greater than or equal to 11 percent, the impact work at -40 DEG C below zero is greater than or equal to 50 J and the straightness in any direction of the steel plate is smaller than or equal to 3 mm / m.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, and in particular relates to a production method of super high-strength steel with high flatness and yield strength of 1100MPa. Background technique [0002] In order to meet the manufacturing needs of large-scale and long-span components, save resources and meet the requirements of environmental protection, construction machinery equipment is developing towards lightweight, and ultra-high-strength steel with a yield strength greater than 1100MPa is used in key components of construction machinery (such as crane booms, etc.) widely used. At present, the application thickness specification is mainly 4-25mm, and the production process is mostly TMCP+quenching+low temperature. The tempered material structure is mainly tempered martensite, and the residual stress is large. Due to the high strength of the steel plate, it is difficult to control the shape of the plate, and the performance is uneve...

AI Technical Summary

Problems solved by technology

Chinese patent 201610587785.6 announced "a steel plate with excellent cold bending performance and yield strength greater than 1100MPa and its preparation method". The ACC is cooled to 630-750°C, and the steel plate is straightened after quenching without tempering, and the steel plate still has a large internal stress, which is prone to problems such as cutting deformation and poor bending accuracy when customers use it.

Chinese patent 201210223610.9 announced "a high-strength steel plate with a yield strength of 1100MPa and its manufacturing method". The alloy element Ni is added by 0.60%-2.00%, and the high alloy content makes the product cost high