PURPOSE: To obtain desired mechanical properties without using an annealing furnace by hot-working a corrosion resistant steel at specific temp. and then applying cooling while specifying cooling velocity to prevent the occurrence of a martensitic microstructure.

CONSTITUTION: An austenite-ferrite steel having 650-850°C transformation point (A3) of carbide is hot-worked at a temp. not lower than the A3 transformation point. Subsequently, the steel is cooled down to a temp. not higher than the A3 transformation point at (10 to 1)°C/min cooling rate. By this procedure, 350MPa proof stress, 520MPa ultimate tensile strength, 25% elongation, and 165 Brinell hardness can be provided, and a composition essentially free from the existence of martensitic microstructure can be provided at ≤5°C/min cooling rate. By this method, the necessity of an annealing process can be obviated and cost reduction can be attained, and also the steel can be hardened.