Sulfur-containing powder-metallurgy tool steel article

Claim 1

A machinable powder metallurgy produced sulfur containing tool steel article comprising a hot worked, fully dense, consolidated mass of nitrogen gas atomized, prealloyed particles of a tool steel alloy comprising in weight percent 0.80 to 3.00 carbon, 0.20 to 2.00 manganese, 0.10 to 0.30 sulfur, up to 0.04 phosphorus, 0.20 to 1.50 silicon, 3.0 to 12.00 chromium, 0.25 to 10.00 vanadium, up to 11.00 molybdenum, up to 18.00 tungsten, up to 10.00 cobalt, up to 0.10 nitrogen, up to 0.025 oxygen, balance iron and incidental impurities, with a maximum sulfide size below about 15 μm.

Claim 6

A method for manufacturing a powder metallurgy sulfur containing tool steel article comprising a hot worked, fully dense, consolidated mass of nitrogen atomized, prealloyed particles of a tool steel alloy having a sulfur content of 0.10 to 0.30 weight percent with a maximum sulfide size of about 15 μm; said method comprising producing said prealloyed particles by nitrogen gas atomization, hot isostatically compacting the prealloyed particles to full density at a temperature of 2165° F. and at a pressure of 15 ksi, hot working the resulting compact to a desired shape of the article at a temperature of 2050° F., and annealing said article.

Claim 7

A method for manufacturing a powder metallurgy sulfur containing tool steel article comprising a hot worked, fully dense, consolidated mass of nitrogen atomized, prealloyed particles of a tool steel alloy having a sulfur content of 0.10 to 0.30 weight percent with a maximum sulfide size of about 15 μm; said method comprising producing said prealloyed particles by nitrogen gas atomization, hot isostatically compacting the prealloyed particles to full density at a temperature of 2165° F. and at a pressure of 15 ksi, hot working the resulting compact to a desired shape of the article at a temperature of 2050° F., and annealing said article.

Claim 8

A method for manufacturing a powder metallurgy sulfur containing tool steel article, comprising a hot worked fully dense, consolidated mass of nitrogen gas atomized, prealloyed particles of a tool steel alloy comprising, in weight percent, 0.80 to 3.00 carbon, 0.20 to 2.00 manganese, 0.10 to 0.30 sulfur, up to 0.04 phosphorus, 0.20 to 1.50 silicon, 3 to 12.00 chromium, 0.25 to 10.00 vanadium, up to 11.00 molybdenum, up to 18.00 tungsten, up to 10.00 cobalt, up to 0.10 nitrogen, up to 0.025 oxygen, balance iron and incidental impurities and with a maximum sulfide size of 15 μm, said method comprising producing said prealloyed particles by nitrogen gas atomization, hot isostatically compacting the prealloyed particles to full density at a temperature of 2165° F. and a pressure of 15 ksi, hot working the resulting compact to a desired shape of the article at a temperature of 2050° F., and annealing said article.

Claim 9

A method for manufacturing a powder metallurgy sulfur containing tool steel article, comprising a hot worked fully dense, consolidated mass of nitrogen gas atomized, prealloyed particles of a tool steel alloy comprising, in weight percent, 0.80 to 3.00 carbon, 0.20 to 2.00 manganese, 0.10 to 0.30 sulfur, up to 0.04 phosphorus, 0.20 to 1.50 silicon, 3 to 12.00 chromium, 0.25 to 10.00 vanadium, up to 11.00 molybdenum, up to 18.00 tungsten, up to 10.00 cobalt, up to 0.10 nitrogen, up to 0.025 oxygen, balance iron and incidental impurities and with a maximum sulfide size of 15 μm, said method comprising producing said prealloyed particles by nitrogen gas atomization, hot isostatically compacting the prealloyed particles to full density at a temperature of 2165° F. and a pressure of 15 ksi, hot working the resulting compact to a desired shape of the article at a temperature of 2050° F., and annealing said article.

Claim 10

A method for manufacturing a powder metallurgy sulfur containing tool steel article having a minimum transverse bend fracture strength of 500 ksi when heat treated to a hardness of 64 to 66 HRC, said article comprising a hot worked, fully dense, consolidated mass of nitrogen atomized, prealloyed particles of a tool steel alloy consisting essentially of, in weight percent, 1.25 to 1.50 carbon, 0.20 to 1.00 manganese, 0.10 to 0.26 sulfur, up to 0.04 phosphorus, up to 1.00 silicon, 3.0 to 6.0 chromium, 4.0 to 6.0 molybdenum, 3.5 to 4.50 vanadium, 4.0 to 6.5 tungsten, up to 0.025 oxygen, up to 0.10 nitrogen, balance iron and incidental impurities with a maximum sulfide size of about 15 μm, said method producing said prealloyed particles by nitrogen gas atomization, compacting the prealloyed particles to full density at 2165° F., and at a pressure of 15 ksi, hot working the compact to a desired shape of the article at 2050° F. and annealing said article.

Claim 11

A method for manufacturing a powder metallurgy sulfur containing tool steel article having a minimum transverse bend fracture strength of 500 ksi when heat treated to a hardness of 64 to 66 HRC, said article comprising a hot worked, fully dense, consolidated mass of nitrogen atomized, prealloyed particles of a tool steel alloy consisting essentially of, in weight percent, 1.25 to 1.50 carbon, 0.20 to 1.00 manganese, 0.10 to 0.26 sulfur, up to 0.04 phosphorus, up to 1.00 silicon, 3.0 to 6.0 chromium, 4.0 to 6.0 molybdenum, 3.5 to 4.50 vanadium, 4.0 to 6.5 tungsten, up to 0.025 oxygen, up to 0.10 nitrogen, balance iron and incidental impurities with a maximum sulfide size of about 15 μm, said method producing said prealloyed particles by nitrogen gas atomization, compacting the prealloyed particles to full density at 2165° F., and at a pressure of 15 ksi, hot working the compact to a desired shape of the article at 2050° F. and annealing said article.

Claim 12

The method of claims 4, 5 or 6 in which the sulfur content is within the range of 0.14 to 0.26 weight percent.