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

Description

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

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 only by this method, 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 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 shortcomings of this method are roughly the same as those of 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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