Non-oriented electrical steel: An overview

Abstract

Worldwide non-oriented electrical steel is the most important soft magnetic material. They account for 80% of the total tonnage of soft magnetic material produced and 56% of the total revenue earned through their commercialization. They are used in the cores of rotating electrical machines like motors and generators where magnetic flux is to be carried in all directions. Non-oriented electrical steels encompasses a wide spectrum ranging from low carbon silicon free steel to be used for small sized fractional horse power motors to 3.5% silicon steel to be used for large generators, In near future, it is not envisaged that any other material can fully substitute CRNO steel as core material for motors and generators. There is a sizable market for CRNO steel in India. It is largely met by import. At present, M/s. EBG India is the biggest producer apart from Rourkela Steel Plant (RSP), Steel Authority of India Limited (SAIL). After the closure of erstwhile Sheet Mill, Tata Steel embarked upon a program to develop CRNO steel through the flat product complex comprising of RH degasser, slab caster, Hot strip Mill. The grades produced at Tata Steel along with their typical properties are discussed. Tata Steel is pioneer in the production of ultra low carbon silicon free electrical steel in India. The quality of non-oriented steel in terms of watt loss, permeability and saturation induction decides the efficiency of motors and generators. Technological advancements in last decade resulted into lower watt loss and higher permeability in CRNO steels. Such endeavors have successfully reduced the size of electrical machines to make them more energy efficient is given in this paper. A brief out line of these developments within special reference to Indian scenario