Control cooling method of easy-welding high-performance steel plate

Abstract

The invention provides a technical scheme of a control cooling method of an easy-welding high-performance steel plate. The easy-welding high-performance steel plate comprises the following chemical components in percentage by weight: 0.05-0.09% of C, 0.1-0.25% of Si, 1.55-1.65% of Mn, 0.025-0.035% of Nb, 0.025-0.035% of V, 0.20-0.30% of Cr, 0.0008-0.0025% of B, 0.020-0.045% of Alt, 0.015-0.030% of Ti and billet of which the low-welding crack sensitivity index Pcm is less than 0.21%; a final steel plate with the thickness of 12-60mm is rolled in a non-recrystallization area, and the effects of dislocations strengthening, precipitation strengthening and phase change strengthening in cooling after rolling are sufficiently realized by adopting different online cooling modes according to different performance requirements of the final steel plate; and the microstructure is controlled according to different performance requirements to obtain a proper complex-phase structure. According to the scheme, flexible control on performance is realized through the flexibility of the cooling technology by use of one component; the produced steel plate has uniform structure, low yield ratio, high plasticity and excellent low-temperature toughness; the steel plate does not need preheating before welding and heat treatment after welding; and the individualized needs of users are met by the flexibility of the production line.

Description

technical field [0001] The invention relates to the technical field of production methods of high-performance steel plates, in particular to a controlled cooling method for easy-weld high-performance steel plates with different functional indicators such as high strength and toughness, low yield ratio, and high elongation. Background technique [0002] Compared with traditional low-carbon steel, high-performance steel not only has higher strength, but also has better low-temperature toughness, weldability and cold formability. Its composition design is based on economical and clean steel, with economical elements Nb, V, Ti, B, etc. replacing precious alloys such as Mo, Ni, etc. to reduce the optimal design, combined with advanced TMCP technology, through precise control of the cooling path to Control the phase transformation process, fully explore the strengthening and toughening ability of fine grain and multiphase structure, and realize the batch supply of high weldability...

AI Technical Summary

Problems solved by technology

An application number 201010295925.5 published by the State Intellectual Property Office of Jiangsu Shagang Iron and Steel Research Institute Co., Ltd. is a patent named "High-strength and low-crack-sensitive thick plate and its manufacturing method". The manufacturing method of the steel with a yield strength of 420MPa produced by the rolling + controlled cooling process has the disadvantages of the low strength level of the steel plate produced, and the narrow adaptation range of the cooling rate and final cooling temperature (9-12°C / s, 470-580 °C), it is difficult to realize the flexible production of multi-functional performance indicators through the adjustment of the follow-up process for the billet of one composition, especially the control of the opening and cooling temperature that affects the volume percentage of the soft and hard phases in the steel, and the low yield ratio cannot be achieved Production of steel; the composition of steel contains precious alloying elements Cu and Ni, which are likely to cause cracks in the slab and steel plate during the actual production process; its composition design still mainly relies on the strengthening effect of alloying elements, which does not reflect the role of controlled cooling in achieving the goal of flexible performance Aspects of role

[0004] The application number of Baoshan Iron and Steel Co., Ltd. published by the State Intellectual Property Office is 200410084699.0, which is called "A Low Yield Ratio Easy-to-Weld Structural Steel Thick Plate and Its Production Method". The patent uses a Ni content as high as 0.30-0.32%, and the Si content reaches 1-1.5%. The composition design system is obviously different from this patent. At the same time, high Si content will increase the sensitivity coefficient of welding cracks and deteriorate weldability

In addition, it achieves a low yield ratio index through the control of the cooling stage. As for how to control the initial cooling, final cooling, and cooling rate cooling parameters to ensure high toughness and plasticity index, it is not mentioned.

[0005] It can be seen from the above two technical solutions that in the prior art, too many alloying elements are added, which not only increases the cost, but also fails to improve the quality of the steel, and at the same time ignores the modern TMCP technology, The accelerated cooling process of rolled steel can play a role in controlling the properties of the steel, which is the deficiency of the existing technology

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