Age-hardenable stainless steel

Claim 2

A chromium-nickel-copper, age-hardenable martensitic stainless steel having improved machinability in both the solution-treated and age-hardened conditions and stress corrosion cracking resistance after aging, characterised in said steel consisting of, in weight percent: carbon plus nitrogen      up to 0.08 manganese      up to 8.0 phosphorus      up to 0.040 sulfur      up to 0.15 silicon      up to 1.0 nickel      2.00 to 5.50 chromium       11.00 to 17.50 molybdenum      up to 3.0 copper      2.00 to 5.00 columbium      up to 15 × (C+N) aluminum       up to 0.05 beryllium      0 to 0.5 boron      0 to 0.01 balance iron with incidental impurities, with the composition of said steel being balanced to have both essentially no delta ferrite according to equation (1) and an M S temperature above 250°F (121°C) according to equation (2).

Claim 3

A steel according to claim 1 having a carbon plus nitrogen content up to 0.05.

Claim 4

A steel according to claim 1 having a carbon plus nitrogen content up to 0.035.

Claim 5

A steel according to claim 1, 2 or 3, having up to 0.030 sulfur.

Claim 6

A steel according to any one of the preceding claims having up to 2.0 manganese and up to 0.50 molybdenum.

Claim 7

A Chromium-nickel-copper, age-hardenable martensitic stainless steel mould having improved machinability in both the solution-treated and age-hardened conditions and stress corrosion cracking resistance after aging, characterised in said mould consisting of, in weight percent: carbon plus nitrogen      up to 0.08 manganese      up to 8.0 phosphorus      up to 0.040 sulfur      up to 0.15 silicon      up to 1.0 nickel      2.00 to 5.50 chromium      11.00 to 17.50 molybdenum      up to 3.0 copper      2.00 to 5.00 columbium      up to 15 × (C+N) aluminum      up to 0.05 beryllium      0 to 0.5 boron      0 to 0.01 balance iron with incidental impurities, with the composition of said mould being balanced to have both essentially no delta ferrite according to equation (1) and an M S temperature above 250°F (121°C) according to equation (2).

Claim 8

A Chromium-nickel-copper, age-hardenable martensitic stainless steel mould having improved machinability in both the solution-treated and age-hardened conditions and stress corrosion cracking resistance after aging, characterised in said mould consisting of, in weight percent: carbon plus nitrogen      up to 0.08 manganese      up to 8.0 phosphorus      up to 0.040 sulfur      up to 0.15 silicon      up to 1.0 nickel      2.00 to 5.50 chromium      11.00 to 17.50 molybdenum      up to 3.0 copper      2.00 to 5.00 columbium      up to 15 × (C+N) aluminum      up to 0.05 beryllium      0 to 0.5 boron      0 to 0.01 balance iron with incidental impurities, with the composition of said mould being balanced to have both essentially no delta ferrite according to equation (1) and an M S temperature above 250°F (121°C) according to equation (2).

Claim 9

A steel mould according to claim 6, having a carbon plus nitrogen content up to 0.05.

Claim 10

A steel mould according to claim 6, having a carbon plus nitrogen content up to 0.035.

Claim 11

A steel mould according to claim 6, 7 or 8, having up to 0.030 sulfur.

Claim 12

A steel mould according to any one of claims 6 to 9, having up to 2.0 manganese and up to 0.50 molybdenum.

Claim 13

A steel mould according to any one of claims 6 to 10 having 2.50 to 3.50 nickel and 11.00 to 13. 00 chromium.