DEVELOPMENT OF MICROALLOYED ULTRA HIGH STRENGTH STEEL

摘要

Conventional mode of production of high strength steel used lower carbon concentration, maintaining lower finish rolling temperatures. Reduction in carbon content during melting increased cost of melting operation of steel and lower finished rolling temperatures required high amount of rolling load and energy. The present invention aims at overcoming of above drawbacks by enhancing the carbon concentration of steel and using higher finish rolling temperatures. This invention provides a novel microalloyed ultra high strength steel having the composition - i) carbon 0.06 - 0.15% by wt.; ii) phosphorus - 0.01% max by wt.; iii) sulphur - 0.01% max by wt.; iv) silicon 0.2 - 0.7% by wt.; v) manganese 1.2 - 1.8% by wt.; vi) nickel 3.0 - 3.8% by wt.; vii) molybdenum 0.4 - l.0% by wt.; viii) copper - 1.5% max by wt.; ix) niobium 0.04 - 0.09% by wt.; x) titanium 0.02 - 0.08% by wt.; xi) aluminium 0.02 - 0.03% by wt.; xii) chromium - 1.5% max by wt. The subject invention also provides a process for preparing the aforesaid ultra high strength steel.