Technical knowledge: technical points of the new method of oriented electrical steel

Oriented electrical steel refers to cold-rolled electrical steel containing 2.9% to 3.5% Si, and the crystal structure of the steel plate has a certain regularity and direction. It is an indispensable soft magnetic material in the power industry. In production, in order to avoid sticky materials during annealing treatment, a MgO type release agent is generally used, that is, a layer of stable inorganic substance is coated on the surface of the steel plate at high temperature. This method will cause moisture on the surface of the steel plate and deteriorate the steel plate. The magnetic properties. Japan JFE company has developed a new method without release agent, technical points:

1. Technical premise:

Try to control the content of S and Se as low as possible, which is an important prerequisite for continuous final annealing without coating annealing separator.

2. Production points:

1) Hot rolling of slab after heating to below 1250℃;

2) The hot-rolled sheet is annealed at 800-1100℃;

3) Perform two or more cold rollings on the annealed hot-rolled sheet, and perform an annealing treatment between the two cold rollings. If decarburization is required, the first recrystallization annealing should be performed in a humid atmosphere; without decarburization, the first recrystallization can be performed in a dry atmosphere;

4) After the first recrystallization, perform a second recrystallization annealing treatment at 700-1000℃, and the annealing time must be more than 5h;

5) The temperature of continuous final annealing treatment without annealing separator is in the low temperature range above 1100℃, and the annealing treatment time should not exceed 30min (less than 10min is more conducive to obtaining excellent magnetic properties). The annealing atmosphere may be an Ar atmosphere, or gases such as H2 and He may be used as the gas for the final annealing atmosphere.

According to the test results of 0.20mm thick oriented electrical steel developed by JFE, the iron loss value (W17/50) of the steel is 0.584-0.648W/kg, indicating that the electrical steel has excellent magnetic properties.