A plastic mold comprises an iron-based alloy comprising (wt.%): 0.25-0.30 carbon; 0.15-0.35 silicon; 0.25-0.65 manganese; 14.0-15.0 chromium; 0.8-1.1 molybdenum; 0.5-1.1 nickel; 0.05-0.18 nitrogen; less than 0.03 phosphorus and 0.005 sulfur; and balance iron and production impurities.
