Manufacturing method for coarse-grain austenitic heat-resistance steel material

The invention relates to a manufacturing method for a coarse-grain austenitic heat-resistance steel material, and belongs to the technical field of heat-resistance steel. The manufacturing method comprises the following steps: austenitic heat-resistance steel tubular products and bars are used, wherein the grain sizes of the austenitic heat-resistance steel tubular products are greater than ASTM (American Society for Testing Material) standard 4-level grain size; when the heat-resistance steel tubular product with a ratio of the wall thickness to the inner diameter being 0.2-1.3, the forming through extrusion is directly carried out, and a processing technology of casting, cogging, boring, heating, extruding, heat preservation or hyperthermic treatment and water cooling are adopted; metal bars with coarse-grain austenitic tissues are produced, and a processing technology of casting, cogging, heating, forging, heat preservation or hyperthermic treatment and water cooling is adopted. Technical parameters for controlling are as follows: after the hot extrusion or hot forging deformation is 30%-95%, the final extrusion or final forging temperature is between 1050 DEG C and 1250 DEG C, and the heat preservation is carried out for 2min to 20min and then the water cooling is carried out in a thermal treatment furnace at the temperature of 1150-1250 DEG C. The coarse austenitic tissues with the grain size of greater than the ASTM standard 4-level grain size are obtained.