a manufacturing mold base for plastic injection molds is formed from a martensitic stainless steel alloy comprising : about 0 . 03 %- 0 . 06 % by weight c , about 1 . 0 %- 1 . 6 % by weight mn , about 0 . 01 %- 0 . 03 % by weight p , about 0 . 06 %- 0 . 3 % by weight s , about 0 . 25 %- 1 . 0 % by weight si , about 12 . 0 %- 14 . 0 % by weight cr , about 0 . 5 %- 1 . 3 % by weight cu , about 0 . 01 %- 0 . 1 % by weight v , about 0 . 02 %- 0 . 08 % by weight n , with the balance being fe with trace amounts of ordinarily present elements .