Method of reducing pickling continuous rolling strip breakage rate of chromium-containing high carbon steel

Abstract

The invention discloses a method of reducing pickling continuous rolling strip breakage rate of chromium-containing high carbon steel. The method comprises the following steps of welding a strip tailof a previous coil of strip steel and a strip head of current strip steel together and achieving first time tempering during welding; and then carrying out second time tempering and third time tempering successively, and carrying out cold continuous rolling after tempering. By controlling process parameters of welding and carrying out tempering processes for three times after welding, the ductility of a weld joint is improved, so that the strip breakage rate of the chromium-containing high carbon steel rolled by a pickling continuous rolling unit is further reduced, and therefore, online highspeed batched production of the chromium-containing high carbon steel on the pickling continuous rolling unit is realized smoothly.

Description

technical field [0001] The invention belongs to the technical field of iron and steel, and in particular relates to a method for reducing the strip breaking rate of chromium-containing high-carbon steel pickling continuous rolling. Background technique [0002] The pickling and tandem rolling unit is a fully continuous high-speed production unit. During production, the tail of the previous strip and the current strip are welded together by laser welding equipment to ensure continuous production and welding of the pickling and tandem rolling unit. Commonly known as the weld. The range of steel types that can be welded by the laser welding machine of the pickling tandem mill is: hot-rolled low-carbon steel, ultra-low-carbon steel, low-alloy high-strength steel, and medium-low grade non-oriented electrical steel, etc. However, Cr-containing high-carbon steel belongs to high-carbon steel, and the alloy element Cr is added, which is not within the welding range of the welding ma...

AI Technical Summary

Problems solved by technology

One of the characteristics of laser welding is that the heat-affected zone is small, the weld seam cooling speed is fast, the thermal conductivity is poor, and the grain growth is fast at high welding temperature, and the carbides are easy to accumulate and grow on the grain boundary, which increases the brittleness of the weld seam. , so that the weld strength is reduced

At the same time, the internal stress in the weld is also large and the elongation is low

Continuous cold rolling is produced with high tension. If the elongation of the weld is too low, it is easy to break the strip under the simultaneous action of large rolling force and high tension.

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