Method of producing a forged article from prealloyed water-atomized ferrous alloy powder

Claim 2

A PROCESS FOR FORGING AN ARTICLE HAVING HIGH IMPACT STRENGTH FROM A METAL POWDER COMPRISING WATER ATOMIZING A CHARGE OF MOLTEN FERROUS ALLOY METAL TO A PREALLOYED IRON METAL POWDER CONSISTING ESSENTIALLY OF ABOUT 0.25 - 0.6 WEIGHT PERCENT MANGANESE, 0.2 - 1.0 WEIGHT PERCENT NICKEL, AND 0.2 - 0.8 WEIGHT PERCENT MOLYBDENUM, SAID PREALLOYED POWDER CONTAINING MINIMAL AMOUNTS OF CARBON AND OXYGEN THE BALANCE BEING SUBSTANTIALLY IRON, MIXING SAID POWDER WITH AN EFFECTIVE AMOUNT OF GRAPHITE TO PROVIDE FOR DESIRED HARDENABILITY, AND FORGING SAID POWDER AND GRAPHITE MIXTURE INTO THE SHAPE OF THE ARTICLE.

Claim 3

The process of claim 1 comprising compacting the powder and graphite mixture into approximately the desired shape of the article, sintering the compacted mixture in a reducing atmosphere, and hot forging the compacted mixture into the shape of the article.

Claim 4

The process of claim 2 in which the sintering step is carried out at least at about 2000*F and the forging step is carried out at an initial temperature of about 1600*F.

Claim 5

The process of claim 3 comprising equalizing the compacted mixture leaving the sintering step at about 1600*F in a reducing atmosphere, and forging the compacted mixture directly after equalizing.

Claim 6

A process for forging an article from a ferrous based metal powder, the article having an impact strength of at least 10 foot-lbs. at -40*F. and a jominy hardenability of at least 56 at J1, 31 at J4, 28 at J8, and 22 at J16, the method comprising: a. water atomizing a charge of molten ferrous alloy metal to form a prealloyed metal powder consisting essentially of 0.25-0.6 weight percent manganese, 0.2-1.0 weight percent nickel, 0.2-.8 weight percent molybdenum, less than 0.1 weight percent carbon, a minimum amount of oxygen, the remainder being substantially iron, b. mixing said water atomized powder with an amount of graphite effective to provide a carbon content in said article of at least 0.4 weight percent, c. forging said powder and graphite mixture at an elevated temperature of about 1600*F. to form the shape of said article, and d. quenching and drawing said article to a hardness of about Rc20.

Claim 7

A process for forging an article from a ferrous based metal powder, the article having an impact strength of at least 10 foot-lbs. at -40*F. and a jominy hardenability of at least 56 at J1, 31 at J4, 28 at J8, and 22 at J16, the method comprising: a. water atomizing a charge of molten ferrous alloy metal to form a prealloyed metal powder consisting essentially of 0.25-0.6 weight percent manganese, 0.2-1.0 weight percent nickel, 0.2-.8 weight percent molybdenum, less than 0.1 weight percent carbon, a minimum amount of oxygen, the remainder being substantially iron, b. mixing said water atomized powder with an amount of graphite effective to provide a carbon content in said article of at least 0.4 weight percent, c. forging said powder and graphite mixture at an elevated temperature of about 1600*F. to form the shape of said article, and d. quenching and drawing said article to a hardness of about Rc20.