Patent ID: 7515395

Claim:
A casing material for a storage cell being made of an austenitic stainless steel comprising C: not more than 0.03 mass %, Si: 0.0 1-0.50 mass %, Mn: not more than 0.20 mass %, P: not more than 0.04 mass %, S: not more than 0.0005 mass %, Ni: 20.0-40.0 mass %, Cr: 20.0-30.0 mass %, Mo: 5.0-10.0 mass %, Al: 0.001-0.10 mass %, N: 0.10-0.50 mass %, Ca: not more than 0.001 mass %, Mg: 0.0001-0.0050 mass %, O: not more than 0.005 mass %, provided that contents of Cr, Mo and N satisfy a relation of the following equation (1), and the balance being substantially Fe and inevitable impurities, in which a content of CaO as an oxide inclusion in steel is not more than 20 mass %: Cr+3.3×Mo+20×N≧43 (1) (wherein each content of Cr, Mo and N is represented as mass %).