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Low-yield-ratio Q370qNH steel plate and preparation method thereof

A low yield ratio, steel plate technology, applied in the field of iron and steel metallurgy, can solve problems such as easy cracking, and achieve the effects of reducing surface cracks, improving strength, and inhibiting grain growth

Inactive Publication Date: 2019-03-19
BAOTOU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the chemical composition contains B elements, which is prone to crack defects, and is only suitable for the production of coils

Method used

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  • Low-yield-ratio Q370qNH steel plate and preparation method thereof
  • Low-yield-ratio Q370qNH steel plate and preparation method thereof
  • Low-yield-ratio Q370qNH steel plate and preparation method thereof

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Effect test

specific Embodiment approach

[0024] The purpose of the present invention is to provide a weather-resistant bridge steel plate with a yield strength greater than 370 MPa, low yield ratio, good corrosion resistance, low temperature toughness, cold forming performance and welding performance, which can be used without coating. The following specific implementation methods will be adopted accomplish:

[0025] In the first embodiment of the present invention, the present invention provides a low yield ratio Q370qNH steel plate, the components of the steel plate are: C: 0.04-0.06%, Si: 0.20-0.30%, Mn: 1.2-1.4%, P: ≤0.015%, S: ≤0.008%, Nb: 0.01-0.02%, Cu: 0.25-0.35%, Ni: 0.3-0.4%, Cr: 0.4-0.5%, Als: 0.024-0.034 %, the balance is Fe and unavoidable impurities.

[0026] According to a preferred embodiment of the present invention, the composition of the above-mentioned steel plate is: C: 0.04-0.06%, Si: 0.21-0.23%, Mn: 1.21-1.25%, P: ≤0.011%, S: ≤ 0.003%, Nb: 0.012-0.015%, Cu: 0.29-0.31%, Ni: 0.32-0.35%, Cr: 0.4...

Embodiment 1

[0035] Smelt according to the chemical composition shown in Table 1, and cast into steel ingots, heat the steel ingots to 1210 ° C, and the total time in the furnace is 252 minutes, and carry out the first stage of rolling on the experimental rolling mill, that is, rolling in the austenite recrystallization zone. The rolling start temperature is 1176°C, the reduction in the first to second passes should be greater than 10%, and the reduction rate in at least 1 to 2 passes should be controlled above 25%. Temperature to 930 ° C, followed by the second stage of rolling, that is, rolling in the austenite non-recrystallized zone. The final rolling temperature is 830°C, and the thickness of the finished steel plate is 14mm. After rolling, the steel plate enters the laminar flow cooling device and is cooled to 630°C at a rate of 10°C / s, and finally the steel plate can be obtained.

Embodiment 2

[0037] The method is the same as in Example 1, wherein the heating temperature is 1220° C., and the total time in the furnace is 256 minutes. The rolling start temperature of the first stage rolling is 1175° C., and the thickness of the intermediate billet is 60 mm. The rolling start temperature of the second stage rolling is 925°C, the final rolling temperature is 836°C, and the thickness of the finished steel plate is 20mm. After rolling, the steel plate enters the laminar flow cooling device and is cooled to 620°C at a rate of 12°C / s, and finally the steel plate can be obtained. Such as figure 1 As shown, the metallographic structure of the steel plate obtained in this embodiment is shown, and it can be clearly seen from the figure that the metallographic structure of the steel plate obtained by the present invention is mainly ferrite and pearlite, and the grains are dense and refined , so that the steel plate prepared by the present invention has strong strength and low t...

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Abstract

The invention provides a low-yield-ratio Q370qNH steel plate and a preparation method thereof. The steel plate is prepared from the compositions in percentage by mass: 0.04-0.06% of C, 0.20-0.30% of Si, 1.2-1.4% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, 0.01-0.02% of Nb, 0.25-0.35% of Cu, 0.3-0.4% of Ni, 0.4-0.5% of Cr, 0.024-0.034% of Als and the balance of Fe and unavoidable impurities. According to the low-yield-ratio Q370qNH steel plate and the preparation method thereof, the obtained Q370qNH steel plate has a low yield ratio, good corrosion-resistant properties, low-temperature toughness, cold shaping properties and welding properties, and can be used without coating; and meanwhile, the characteristics that the preparation technological process is simple, the production period is short and the production cost is low are achieved.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a low yield ratio Q370qNH steel plate and a preparation method thereof. Background technique [0002] my country's bridge steel has developed from the initial A3 grade to the current Q500q. The traditional bridge steel is not only unsatisfactory in impact toughness, weldability, fatigue, etc., but also has worse performance in atmospheric and marine corrosion resistance. With the increasing span of modern bridges, the safety and reliability of bridge structures are becoming more and more stringent. This is not only a huge challenge for bridge designers, but also puts forward higher requirements for the performance of bridge steel. It must not only have high strength to meet the requirements of lightweight structures, but also have excellent low temperature toughness and weldability. , corrosion resistance and fatigue performance, as well as low maintenance co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/48C22C38/42C22C38/06C21D8/02
CPCC21D8/0226C21D2211/005C21D2211/009C22C38/02C22C38/04C22C38/06C22C38/42C22C38/48
Inventor 杨雄成永久麻晓光王全录高军杨维宇周可哥张宁
Owner BAOTOU IRON & STEEL GRP
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