High grade cold rolling non-oriented silicon steel and method for manufacturing same

Abstract

The invention provides a middle and high grade cold rolled no-orientation silicon steel and a manufacturing method for the no-orientation silicon steel, the components of which are C: 0.0015%-0.005% Si: 1.60%-3.30% Mn: 0.50-2.50% P<=0.050% S: 0.0010%-0.0050% Al: 0.15%-0.50% and N: 0.0010%-0.0050%, small amount of Sn, Sb, Cu can be added, total mount is <0.20%, the remainder are Fe and unavoidable foreign matters and Mn%=k is multiplied by |Si+2Al-2.05|%+0.28%, wherein, k=1.0-3.0. The manufacturing method is like follows: hot rolling, pickling, cold rolling and annealing the cast blanks of above components. The heating temperature for the cast blanks at hot rolling is 1050-1200 DEG C, the rolling passes are 3-5 no.s, the pressure-down rate is 20-40% for each pass; the temperature for fine and final rolling temperature is 800-900 DEG C, coiling temperature is 600-680 DEG C, and the annealing is done in a dry protective atmosphere. The method is of low process difficult, low cost and high product surface quality.

Description

Technical field [0001] The invention relates to a medium-to-high grade cold-rolled non-oriented silicon steel and a manufacturing method thereof, in particular to a medium-to-high grade cold-rolled non-oriented silicon steel hot-rolled with a Si content of more than 1.6%, and to a manufacturing method of the silicon steel. Background technique [0002] (Si+Al)%>1.7% and C≤0.01% silicon steel has no phase change during solidification and hot rolling. Coarse (100) columnar crystals in the cast slab during hot rolling cannot be prevented due to slow dynamic recovery and slow recrystallization. Completely broken, there are coarse and elongated deformed grains near the thickness center of the hot-rolled plate, mainly {100}<011> fiber texture with extremely low deformation storage energy, which is difficult to recrystallize during subsequent cold rolling and annealing. Corrugated defects are formed on the surface of the finished board. This not only affects the appearance qual...

AI Technical Summary

Problems solved by technology

Production practice shows that when the equiaxed ratio of the slab is less than 60%, it is difficult to completely eliminate corrugated defects by this method alone, and the continuous casting process is not easy to control, the inclusions in the crystallizer are not easy to float up, and the number of inclusions in the continuous casting slab increases , affecting the performance of the final product

[0004] (2) The hot-rolled sheet normalization method is one of the effective methods to prevent corrugated defects, but the investment in equipment is large, the process is complicated, and the production cost increases significantly

[0005] (3) High-temperature coiling self-annealing method for hot-rolled plates. The high-temperature coiling self-annealing of hot-rolled plates needs to increase the heating temperature during hot rolling, which will easily cause the continuous casting billet to collapse. In addition, it will also cause sulfide, Nitride solid solution again, precipitated in a dispersed form in the subsequent hot rolling process, which hinders the growth of the annealed grain of the finished product and deteriorates the magnetic properties

This technology mainly uses equipment to realize the production of non-oriented electrical steel without corrugated defects. Its shortcoming is that it has high requirements for production equipment, and it is only suitable for small casting slab thickness and compact configuration of continuous casting and continuous rolling. The short-process production line is difficult to work for the traditional continuous casting-hot rolling production mode, and the process versatility is poor

In addition, this technology cannot completely eliminate the hot-rolled strip annealing or secondary cold-rolling process before cold rolling, which greatly reduces production efficiency and increases manufacturing costs

Patent No. 03116890.6 Non-oriented electrical steel sheet without corrugated defects and its manufacturing method. Although this method can save the hot-rolled sheet normalization process, it has the following disadvantages: 1) The C content in the steel is high, and it needs to be annealed when the finished product is annealed. Decarburization treatment, which not only reduces the operating efficiency of the unit, but also tends to produce inner oxide layers and inner nitride layers during the annealing process, which deteriorates the magnetic properties; 2) Hot-rolled coils need to be coiled at a high temperature above 700°C during the hot rolling process , resulting in dense oxide scales on the surface of hot-rolled coils, which increases the burden of pickling; 3) Higher requirements for production process control accuracy affect production rhythm and efficiency

Application No. 200510027313.7 Non-oriented electrical steel and its manufacturing method, the disadvantage of this method is roughly the same as Patent No. 03116890.6, and it is only suitable for the production of cold-rolled non-oriented electrical steel with low Si content (<1.30%)

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