Preparation method of pure austenitic stainless steel

The invention discloses a preparation method of pure austenitic stainless steel. The preparation method comprises the following steps of (1) smelting, specifically, taking raw materials to be smeltedinto molten steel, and adding a lanthanum-cerium rare earth alloy and metal calcium before tapping and casting at the casting temperature of 1490-1560 DEG C; (2) electroslag remelting, specifically, preparing a steel ingot by electroslag remelting; (3) high-temperature diffusion, specifically, diffusing the steel ingot by adopting a high-temperature furnace, wherein the diffusion temperature is 1150-1300 DEG C; (4) forging and cogging, specifically, forging the product obtained in the step (3), wherein the initial forging temperature is controlled to be 1120-1280 DEG C, and the final forging temperature is controlled to be 900-1050 DEG C; (5) hot rolling, specifically, enabling the product obtained in the step (4) to be subjected to hot rolling, wherein during hot rolling, the blank heating temperature is 1150-125