These are 116BCD, and according to St. Sheldon, the smallest ring is 35T: Sheldon Brown's Bicycle Crank/Chainring Bolt Circle Diameter Crib Sheet

There were a lot of steel rings sold in this size by Japanese makers. You might try a local co-op.

Otherwise, Hilary Stone has a 40T in stock: Hilary Stone Chainrings 3-Arm