Friday, 07 September 2012 03:33

No6.Clean Manganese Steel

Steel cleanliness is an important factor of steel quality and the demand for cleaner steels increases every year. The so-called clean steel generally is the steel in which the content of impurity elements, such as phosphorus, sulphur, total oxygen, nitrogen, hydrogen (including carbon sometimes) and inclusions are very low. The improvement of steel cleanliness has therefore become a more and more important subject in the development of ferrous metallurgical technology, and also an important task for the iron and steel producers.

Manganese steel has been round for about 200 years, researchers and producers have never stopped trying different ways to increase the mechanical properties of manganese steel. Changing the composition by adding elements such as molybdenum, rear earth, boron, in some cases, this method has been proven very useful but in other cases results are not conclusive. We now have 14% manganese, 18% manganese and 21% manganese liners for different working conditions, in rear cases, producers are now offering 25% manganese steel.

MnSteels has been producing manganese steel liners for 20 years and tried quite a few different approaches trying to improve product quality. But as well as trying different compositions, MnSteels has always focused on producing the "cleanest" manganese steel. In order to obtain the satisfactory cleanliness of steel it is necessary to control and improve a wide range of operating practices throughout the steelmaking processes like deoxidant- and alloy additions, secondary metallurgy treatments, shrouding systems and casting practice.

Electric arc furnaces and induction furnaces are commonly used for manganese steel melting, both with its own advantages and disadvantages. MnSteels uses induction furnaces knowing the one major drawback to induction furnace: the lacking of refining capacity; charge materials must be clean of oxidation products and of a known composition, and some alloying elements may be lost due to oxidation. MnSteels dose the following to ensure the cleanness of the melt:

1. Clean material - each batch of material is properly tested and only from qualified suppliers,

2. Melt - argon blowing process during melt to clean the liquid metal, as well as applying MnSteels own refining process.

3. ladle - argon blowing and bottom pour ladle, bottom pouring creates steel with superior cleanness and promotes excellent surface quality.

Over the years of practice, random test results show oxygen and hydrogen levels in GW's melt are very low: 1PPM≤H≤2PPM, 5PPM≤O≤15PPM. Below are a comparison of metallographic of two products with and without GW's refine process:

Refined Not Refined