CRNGO: Cold Rolled Non-Oriented Electrical Steel (Non-Oriented Electrical Steel)

22 Nov 2023
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GNEE cold rolled non oriented electrical steel

The term oriented, when used in conjunction with electrical steels, refers to a crystal structure having magnetic properties that are materially better in a given direction. Some silicon steels are not intentionally oriented and can be called non oriented  steels. 
For all practical purposes, Electrical Steels, from grades M-15 to M-47, are non oriented materials. In other words, their magnetic properties with respect to the direction of rolling are primarily random. In applications such as motor laminations, where flux may flow in any direction with respect to the rolling direction, and in many other applications where cost of producing the part is of paramount importance, the nonoriented grades provide satisfactory performance.
CRNGO steel usually has a silicon level of 2 to 3.5% and have similar magnetic properties in all directions in plan of the sheet. Non-oriented Electrical steel are principally used for motors, generators, alternators, ballasts, small Transformers and a variety of other electromagnetic applications.
Non-oriented electrical steels do not use a secondary recrystallization process to develop their properties, and high temperature annealing is not essential. Therefore, a lower limit on silicon, such as is required for the oriented grades, is not essential.

non-oriented electrical steel

cold rolled electrical steel

Microstructure of CRNGO

Non-oriented electrical steel grades contain between 0.5 and 3.25% Si plus up to 0.5% Al, added to increase resistivity and lower the temperature of primary recrystallization. Grain growth is very desirable in the (CRNGO) non-oriented electrical steel grades, but is generally much smaller than for the oriented electrical steel CRGO grades.Processing to hot rolled band is similar to that described for the oriented grade. After surface conditioning, the bands are usually cold rolled directly to final gage, and sold to the transformer manufacturer in one of two conditions fully-processed, or semi processed. After final cold rolling, the strip is annealed, decarburizing it to 0.005% C or lower and developing the grain structure needed for the magnetic properties. Samples are then taken from each coil end, and tested.
Non-oriented steels CRNGO are not as sensitive to strain as the oriented product. Consequently, shearing strains constitute the only strain effects, which should degrade the magnetic quality. Because laminations are generally large, these shearing strains can be tolerated. Most of the fully processed grades are used as stamped laminations in such applications as rotors and stators.
The non-oriented electrical steels (CRNGO) have a random orientation. They are commonly used in large rotating equipment, including motors, power generators, and AC alternators. Fully processed steels are given a “full” strand anneal (to develop the optimum magnetic quality), making them softer and more difficult to punch than semi-processed products. Grades with higher alloy content are harder and thus easier to punch.

 
Grade Processing
M-15 Fully Processed
M-19 Fully Processed
M-22 Fully Processed
M-27 Fully Processed
M-36 Fully Processed
M-43 Fully Processed, Semi-Processed
M-45 Fully Processed
M-47 Fully Processed, Semi-Processed
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