High-strength ultra-fine grain stainless steel

The invention relates to the technical field of stainless steel, and particularly discloses high-strength ultra-fine grain stainless steel which comprises the following components in percentage by weight: 0.012%-0.025% of carbon element, 8.0%-12.0% of chromium element, 0.5%-1.0% of manganese element, 0.8%-2.0% of nickel element, 0.5%-2.0% of molybdenum element, 0.20%-0.80% of copper element, 0.11%-0.15% of niobium element and the balance of iron element. The average performance strength of the high-strength ultra-fine grain stainless steel is higher than that of common A-E grade and high-strength grade AH40-FH40, the section elongation and impact are both higher than those of the common A-E grade and high-strength grade AH40-FH40, the carbon content of the high-strength ultra-fine grain stainless steel is lower than that of high-strength structural steel and is only 0.012%-0.025%, high welding performance of the high-strength ultra-fine grain stainless steel is guaranteed, the surface is smooth and clean afte