Electro 500D LPS (Low Phosphorus-Sulphur) is a grade of TMT Bars of Electrotherm (India) Limited wherein the phosphorus and sulphur contents are limited to minimum levels. As part of the chemistry, any rebar necessarily contains Sulphur (S) and Phosphorus (P) in varying levels. Excess levels of Sulphur leads to “Hot Shortness” wherein the melting point of steel is lowered, leading to failure under extreme high temperature conditions. Excess levels of Phosphorus leads to “Cold Shortness” wherein the steel becomes brittle under extremely cold conditions and leads to cracking. Therefore lowering their contents makes the steel better.
The most frequently asked questions related to LPS are…
Desired quality steel can be produced only if the raw material is of desired quality. Steel produced through inconsistent quality scrap route possesses uncertain chemical and mechanical properties due to inclusion of tramp elements. Secondary steel producers rely on suppliers for scrap or DRI. They don’t have provision for decreasing the phosphorus content and removal of tramp elements present in the scrap. Thus the steel produced may have tramps detrimental to required properties. LPS Steel produced through virgin iron ore route at Electrotherm (India) Limited ensures high cleanliness and homogeneous quality. We use virgin iron ore for blast furnace and for producing DRI which is used as raw material for producing LPS steel. Phosphorus is controlled with patented process up to required level and no problem of tramp elements is faced due to non usage of scrap. Thus the steel produced is of prime quality.
LRF: Ladle Refining Furnace. Steel produced by crude processes is not completely free from impurities which may lower its strength. For producing desired chemistry its further refining is needed. This refining is done at Electrotherm Ladle Refining Furnace .The objectives of this refining are Removal of Oxygen (Deoxidation), Removal of Hydrogen (Degassing), to reduce Sulphur concentrations (Desulphurization), Removal of refractory inclusions , grain refinement and Improve the microstructure (Homogeneity) thus increasing Strength & Ductility of LPS Steel.
Steel is specified and valuated from the functional point of view over mainly two dimensions – chemical properties and mechanical properties. Steel produced through the scrap route has no precise control on chemical properties like phosphorus & sulphur contents, tramp elements contents, inclusions, gases contents and mechanical properties like ductility, strength and bend ability.
To meet the stringent phosphorus and sulphur requirements a unique and patented ERF-ELdFOSTM metallurgical process is used to dephosphorize the steel in the Ladle and desulphurize the steel in ELECTROTHERM LADLE REFINING FURNACE (LRF). This unique process enables to homogenize the metal, control of alloying elements in a very narrow range, dilution of dissolved gases through mild purging of inert gases and removal or chemical alteration of inclusions to ensure high quality of steel.
Along with the load of building- slabs, beams, columns, live load of the people and their belongings TMT bars must also withstand natural calamities like winds, storms and most importantly earthquakes. The Steel to be used for such applications must be highly ductile. Lower phosphorus increases ductility, lower carbon increases ductility and weldability. Higher UTS/YS ratio and percentage elongation of LPS STEEL reflect the ability to withstand the devastating effects of earthquakes. Higher these values, the better. Grain size has a measurable effect on most mechanical properties. Yield strength, tensile strength, fatigue strength and impact strength all increase with decrease in grain size. Hence fine grain size is favorable for steel with better mechanical properties. Special treatment and controlled cooling is done to achieve fine grained steel. Thus LPS grade of Electrotherm (India) Limited is the most suitable grade for all critical applications like Critical structures in seismic zones III, IV and V, High-rise buildings ,Bridges, Flyovers, Dams, Foundation of wind turbines, Industrial Structures, Concrete roads, Underground structures, Thermal and hydro electric power stations, General purpose concrete re-enforcement structures.
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