PURPOSE: To produce a high tensile strength hot rolled steel plate for working, combining superior strength, ductility, ring forgig characteristic, and weldability.

CONSTITUTION: This steel plate is a hot rolled high tensile strength steel plate with high workability, which has a composition consisting of 0.05-0.40%C, >0.05->0.8% Si, 0.8-2.5% Mn, 0.8-2.5% sol.Al, and the balance Fe with inevitable imprities and also has a structure composed essentially of polygonal ferrite and containing ≥5%, by volume ratio, of retained austenite and in which crystalline grain size is regulated to ≥12 ASTM grain size number. A material steel with this chemical composition is reheated to a temp. not lower than the Ac3 point, held at this temp. and hot-rolled, and the resulting steel plate is heated between the rolls of ≥ at least two stands in the latter stage of a finishing mill, finish-rolled while regulating the total draft in the temp. region between (Ar3 point -50°C) and (Ar3 point +100°C) to ≥30%, and subjected to accelerated cooling down to 300-450°C at (5 to 60)°C/s cooling rate and the to coiling, by which the objective steel plate can be formed.