High strength hot rolled steel plates and sheets excellent in uniform elongation after cold working and process for producing the same

Abstract From the Canadian patent

The present invention provides hot rolled steel plates and sheets having a tensile strength of 34 to 62 kgf/mm2 and excellent in a uniform elongation even after cold working the steel plates and sheets to give round and square tubes shapes, sheet piles, etc. to such an ordinary degree that the productivity is not lowered, and a process for producing the hot rolled steel plates and sheets. The hot rolled steel plates and sheets contain from 0.04 to 0.25% of C from, 0.0050 to 0.0150% of N and from 0.003 to 0.050% of Ti also, contain from 0.0008 to 0.015% of TiN having a particle size exceeding 1 µm and dispersed in the matrix thereof and have, Ceq. (WES) of 0.10 to 0.45%. The process …