A kind of low alloy steel with high strength and toughness and preparation method thereof

Abstract

The invention discloses low-alloy steel high in strength and toughness performance and a preparing method of the low-alloy steel. The preparing method is a reasonable matching method for improving the strength and toughness performance in the manner that the aspects of component improvement, short-procedure design in which casting blank reheating is omitted, casting blank core part quality improvement, structure micronization control and rolling schedule optimization are taken into comprehensive consideration, the technical skill potential of modern material machining is fully reflected, and the actions of grain refinement, controlled rolling, rapid cooling and other technology means on steel strengthening and toughening are brought into play. It is ensured that brittle phase crack initiation of products of moderate-thickness plates is reduced and a new structure form is obtained so as to prevent crack expanding, and the breakthrough of the short-procedure technology of direct hot rolling of the ultrahigh strength and toughness steel casting blank is achieved.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a low-alloy steel with high strength and toughness and a preparation method thereof. Background technique [0002] High-performance steel (HPS) is a new generation of steel with higher strength, better toughness, weldability, cold formability and corrosion resistance than traditional low-carbon steel, and is resistant to brittleness in practical applications. The fracture performance has been significantly improved and improved to meet the harsh operating environment and alternating load conditions of high-end equipment such as marine engineering, engineering machinery, bridge construction, and pipeline construction. High strength, high plastic toughness, and easy welding Requirements for functional indicators such as resistance and crack arrest. In the context of the current society as a whole focusing on the safety of large components, the use of high-perform...

AI Technical Summary

Problems solved by technology

[0007] When the above-mentioned common manufacturing method is used to produce this kind of high-performance micro-alloyed steel, if important technical measures such as light pressing of the slab and electromagnetic stirring are not taken to prevent the defects of the slab and improve the quality of the slab, the central area of ​​the slab will eventually solidify. Cause internal quality problems such as porosity, porosity, and component segregation, which affect the performance uniformity and quality level of the final product in the thickness direction

[0008] Moreover, in the process of continuous casting, molten steel solidification and cooling to room temperature, the C and N compounds in the steel will concentrate in the columnar grains or austenite grain boundaries and precipitate, easily forming brittle phases, and the billet will form the third brittle temperature zone; if the subsequent process For example, the control of billet reheating system, rolling system, etc. is not standardized, and these brittle phases are easily inherited and retained in the final steel plate product

When the steel product is subjected to external stress far below its strength limit, the base metal is prone to defects such as brittle cracking, which affects the strength and toughness of the steel. chemical and other security requirements

[0009] Therefore, in the actual production, it is necessary to control the gas and inclusion content in the steel during the refining process, the reasonable control of the process parameters in the continuous casting process, the control of the heating system for slab reheating, the control of the rolling reduction procedure, and the rapid cooling system after rolling, etc. Strict requirements are put forward by many factors, resulting in a long manufacturing process for high-performance steel products, complex production control, and high requirements for production support capabilities; steel billets are cooled to room temperature and then reheated, resulting in high energy consumption in manufacturing, waste of resources, and the occurrence of unqualified products The probability also increases, which ultimately affects the pass rate and profit margin of finished products

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