An economical 690mpa high-strength steel plate and its preparation method

Abstract

The invention discloses an economical 690MPa high-strength steel plate and a preparation method thereof. The high-strength steel plate contains the following chemical components in mass fractions: C: 0.17%-0.20%, Si: 0.25-0.40%, Mn: 1.35%- 1.50%, P≤0.020%, S≤0.015%, Als: 0.020~0.040%, Cr: 0.20%~0.30%, Nb: 0.010%~0.020%, Ti: 0.015~0.025%, B: 0.0015~0.0025%, The rest are Fe and unavoidable impurities; and satisfy Mn+Cr≥1.60%, CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15≤0.50%; the invention is economical The yield strength of the high-strength steel plate is ≥690Mpa, the tensile strength range is 770-900MPa, the elongation after fracture is ≥15%, and the Charpy impact energy (longitudinal) KV at ‑20°C 2 ≥80J, the welding performance of the steel plate is good, and it is suitable for the production of high-strength structural steel parts of most construction machinery on the market without special requirements.

Description

technical field [0001] The invention relates to the technical field of high-strength structural steel manufacturing, in particular to an economical 690MPa high-strength steel plate and a preparation method thereof. Background technique [0002] With the vigorous development of the domestic steel structure industry, construction machinery, ore machinery and other industries, construction machinery such as cranes, excavators, and cantilever cranes are developing towards large-scale and high-strength products. Favored by users, it is widely used and has a large market demand. The steel industry has done a lot of research on this grade of steel. Many domestic steel companies have the production capacity of this grade of steel, and the market competition is becoming increasingly fierce. With the impact of the international trade market, the price of bulk raw materials required for steelmaking fluctuates greatly. In 2020, the procurement cost of iron ore and steel scrap will incre...

AI Technical Summary

Problems solved by technology

During the production design of this product, C is located in the crack-prone area of ​​peritectic steel, and surface cracks are prone to occur during pouring, which is not conducive to the hot delivery of the slab.

In addition, the steel is added with Nb and V precious alloys, which increases the alloy cost

Due to the low C content and no addition of hardenable elements such as Cr and Mo, the ability of the steel plate to obtain martensite is limited when it is cooled. In order to make up for the insufficient strength of the bainite structure, more Mn needs to be added for strengthening, which increases the cost of the Mn alloy.

At the same time, when the Mn content is high, it is easy to aggravate the degree of segregation, which is unfavorable to the performance of the steel plate core

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