A rare earth weather-resistant bridge steel plate with a yield strength of 370mpa and its preparation method

A technology with a yield strength of 370mpa, applied in the field of rare earth weather-resistant bridge steel plates with a yield strength of 370MPa and its preparation, can solve the problems of easy cracks and other problems, and achieve the effects of short production cycle, low production cost and simple preparation process

Active Publication Date: 2020-02-21
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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  • A rare earth weather-resistant bridge steel plate with a yield strength of 370mpa and its preparation method
  • A rare earth weather-resistant bridge steel plate with a yield strength of 370mpa and its preparation method
  • A rare earth weather-resistant bridge steel plate with a yield strength of 370mpa and its preparation method

Examples

Experimental program
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Effect test

preparation example Construction

[0025] The present invention also provides a method for preparing the above-mentioned weather-resistant bridge steel plate, which includes the following steps:

[0026] Step 1), smelting according to the above chemical composition, and casting into a rectangular steel ingot;

[0027] Step 2), steel ingot is heated and rolled, wherein:

[0028] During the heating process, the heating temperature is 1200℃~1220℃, and the total time in the furnace is ≥240min;

[0029] Rolling is divided into first stage and second stage rolling:

[0030] The first stage is rolled in the austenite recrystallization zone. During the rolling process, the rolling start temperature is 1130-1180°C. The reduction in the first to second passes should be greater than 10%, and the rest should be at least 1 to 2 passes. The drop rate is controlled above 25%;

[0031] The second stage is rolled in the austenite non-recrystallized area, the starting rolling temperature is ≤930°C, the thickness of the interm...

Embodiment 1

[0042]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

[0044] The implementation is the same as in Example 1, wherein the heating temperature is 1220°C, the total time in the furnace is 256 minutes, the rolling start temperature of the first stage rolling is 1175°C, the thickness of the intermediate billet is 60mm, and the rolling start temperature of the second stage rolling is The temperature 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. The metallographic structure of the steel plate is shown in figure 1 shown.

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Abstract

The invention relates to a rare earth weather-resistant bridge steel plate with the yield strength being 370 MPa grade and a preparation method thereof. The preparation method comprises the steps thatsmelting and casting are conducted; heating and rolling are conducted, specifically, the heating temperature is 1200-1220 DEG C, the total in-furnace time is larger than or equal to 240 min, during rolling, rolling of the first stage is conducted in an austenite recrystallization zone, the rolling starting temperature is 1130-1180 DEG C, the reduction quantity from the first pass to the second pass is larger than 10%, and the reduction rate of at least 1-2 of the rest passes is controlled to be 25% or above, rolling of the second stage is conducted in an austenite non-recrystallization zone,the rolling starting temperature is smaller than or equal to 930 DEG C, the thickness of an intermediate blank is 2.0-3.5 times of the thickness of a finished product, and the finished rolling temperature is 830-850 DEG C; and cooling is conducted. The yield strength of the steel plate is larger than 370 MPa, the steel plate has the advantages of being low in yield ratio, good corrosion resistantperformance, low-temperature toughness, cold-forming performance and welding performance and capable of being used without coating, the production technological process is simple, the production period is short, and the cost is low.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to a rare earth weather-resistant bridge steel plate with a yield strength of 370 MPa 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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/48C22C38/42C22C38/06C21D8/02
CPCC21D8/0226C21D2211/005C21D2211/009C22C38/005C22C38/02C22C38/04C22C38/06C22C38/42C22C38/48
Inventor 杨雄高军吴章忠王雪莲黄利姜秉坤卢晓禹王海明
Owner BAOTOU IRON & STEEL GRP
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