Process for producing low-alloy high-strength medium plate with 0 to 0.05 percent of arsenic content

Abstract

The invention relates to a cooling process of a medium steel plate, in particular to a process for producing a low-alloy high-strength medium steel plate with 0 to 0.05 percent of arsenic content, which comprises rough rolling, finishing rolling, final rolling and controlled cooling after rolling, wherein the controlled cooling after rolling adopts secondary cooling, the primary cooling is to cool the medium steel plate subjected to final rolling to an upper limit of a carbide forming temperature zone, and the secondary cooling is to cool the medium steel plate to bainite transformation temperature rapidly and preserve the heat to finally obtain a thinned tissue structure. The process comprises the following steps: firstly, cooling to the upper limit of the carbide forming temperature zone by air cooling or slow water cooling at the temperature of between 700 and 760 DEG C; secondly, rapidly cooling to bainite transformation temperature of 400 to 500 DEG C at 15 to 30 DEG C / s; thirdly, preserving the heat; and finally obtaining the thinned tissue structure. The process maximally ensures that the medium steel plate has enough cooling speed in a carbide precipitation temperature zone, thereby inhibiting the precipitation of carbide in the medium steel plate and stabilizing the tissue structure and mechanical property of the low-alloy high-strength medium steel plate.

Description

technical field [0001] The invention belongs to the field of steelmaking, and relates to a cooling process for a medium-thick steel plate, in particular to a production process for a low-alloy high-strength medium-thick steel plate with an arsenic content of 0-0.05%. Background technique [0002] In recent years, with the rapid development of industries such as energy and shipbuilding, low-alloy high-strength steel grades and controlled rolling and controlled cooling technology have achieved rapid development. Body structure, thus obtaining high-strength steel has become the mainstream technology. Among them, the controlled rolling and controlled cooling technology mainly includes two types, one is to reach the bainite transformation temperature zone at a faster cooling rate after final rolling, and the other is to cool to a low temperature at a faster rate and then temper to obtain corresponding organizational structure. The former has the problem of unstable product perf...

AI Technical Summary

Problems solved by technology

Due to the limited ability of iron-making raw materials to remove arsenic during sintering and blast furnace production, arsenic in steel in steelmaking and refining processes tends to be gradually enriched, resulting in excessive arsenic content in molten steel

A large number of production practices have shown that high arsenic content is very unfavorable to the production of low-alloy high-strength steel. A prominent problem is that the drop-weight tear performance of high-strength steel fluctuates greatly, making the drop-weight tear of medium-thick steel plates low performance pass rate

[0005] When the arsenic content in the low-alloy high-strength medium-thick steel plate is slightly high, due to the strong carbon emission characteristics of arsenic, it will cause a large number of spherical carbide inclusions and precipitation, and a large amount of niobium carbide and other precipitates will be deposited on the surface of these inclusions at the same time. It not only reduces the impact toughness of steel, but also affects the precipitation strengthening effect of alloying elements such as Nb

To solve this problem in actual production, more expensive ores imported from abroad are often used. Although the content of arsenic is reduced and the pass rate of medium-thick steel plate production is increased, the cost is increased and the competitiveness of domestic ores is weakened.

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