Wear resistant cast iron alloy with spheroidal graphite separation and manufacturing method therefor

Method for producing a cast piece of a cast iron alloy of high strength and containing spheroidal graphite precipitates for the manufacture of machine parts subject to wear, the cast iron alloy having the following composition:

• 1.5 to 3.0% carbon
• 3.0 to 6.0% silicon
• 0.1 to 2.0% manganese
• 0.05 to 0.5% phosphorus
• up to 0.15sulfur
• 0.1 to 1.0% chromium
• 0 to 3.5% vanadium
• 0. 1 to 2.5% molybdenum
• 0.1 to 3.0% total of at least one element from the group nickel and cobalt
• 0.1 to 3.5% copper
• 0.1 to 2.5% tungsten
• 0.1 to 1.0% total of at least one element from the group titanium, niobium and tantalum
• up to 0.15% magnesium
• up to 0.15% nitrogen,
• remainder iron including impurities inherent in the manufacturing process,
• said cast iron alloy having a tempered structure in which the graphite is formed by a heat treatment process in which ledeburite decomposes, the graphite being present in an extremely fine form and with a high number of spheroids of about 300,00 to 900,000 per cm.sup.2,
• comprising inoculating a cast iron melt with 0.1 to 1.0% ferrosilicon containing 0.5 to 2.0% magnesium, casting the cast iron melt to harden ledeburitically to form a cast piece, and then subjecting the cast piece to a graphitization annealing, subsequently quenching from a temperature above 700.degree. C., and then tempering above 300.degree. C.

Method for producing a cast piece of cast iron alloy of high strength and containing spheroidal graphite precipitates for the manufacture of machine parts subject to wear, the cast iron alloy having the following composition:

• 1. 5 to 3.0% carbon
• 3.0 to 6.0% silicon
• 0.1 to 2.0% manganese
• 0.05 to 0.5% phosphorus
• up to 0.15% sulfur
• 0.1 to 1.0% chromium
• 0 to 3.5% vanadium
• 0.1 to 2.5% molybdenum
• 0.1 to 3.0% total of at least one element from the group nickel and cobalt
• 0.1 to 3.5% copper
• 0.1 to 2.5% tungsten
• 0.1 to 1.0% total of at least one element from the group titanium, niobium and tantalum
• up to 0.15% magnesium
• up to 0.15% nitrogen,
• remainder iron including impurities inherent in the manufacturing process,
• said cast iron alloy having a tempered structure in which the graphite is formed by a heat treatment process in which ledeburite decomposes, the graphite being present in an extremely fine form and with a high number of spheroids of about 300,00 to 900,000 per cm.sup.2,
• comprising inoculating a cast iron melt with 0.1 to 1.0% ferrosilicon containing 0.5 to 2.0% magnesium or at least one of the rare earth metals of cerium, yttrium, lanthanum, neodymium and praseodymium, or a mixture of magnesium and at least one of said rare earth metals, the total amount of magnesium and the rare earth metals in the ferrosilicon being 0.5 to 2.0%, casting the cast iron melt to harden ledeburitically to form a cast piece, and then subjecting the cast piece to a graphitization annealing, subsequently quenching from a temperature above 700.degree. C., and then tempering above 300.degree. C.