Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese

Definitions

• This invention relates to a novel, shock resisting steel having a good combination of high strength, ductility, toughness, and hardness, and particularly to shear blades fabricated therefrom.
• Shock resisting steels find particular application as shearing tools such, for example, as shear blades, cutofif tools on forging or heading machines, trimming dies, blank dies, slitters, punches and piercers.
• shearing tools such as shear blades, cutofif tools on forging or heading machines, trimming dies, blank dies, slitters, punches and piercers.
• Such applications subject the steel to high stresses which increase as the stock thickness increases and, consequently, the steel must possess sufficient hardness and toughness to maintain the original edge contour and dimensions.
• Shear blades for shearing heavy metal sections e.g., blades for shearing nickel cathodes
• Shear blades for shearing heavy metal sections is an application requiring the steel to perform under extreme conditions. In order for the steel to avoid deformation or spalling and to otherwise perform adequately in this operation, it must have a good combination of strength, ductility, toughness and Wear resistance.
• the steel should have a minimum yield strength of about 280,000 p.s.i., an ultimate strength of at least about 325,000 or 330,000 p.s.i., a minimum Charpy C-notch toughness of about 90 foot-pounds at room temperature, a minimum elongation of about in 1 inch, a minimum reduction of area of about 20%, a minimum notch tensile strength of about 190,000 p.s.i., and a minimum hardness of about Re 57.
• a minimum hardness of about Rc 57 is particularly important since below this hardness the blade edge rapidly deforms in service resulting in short blade life and poor shearing characteristics.
• Low blade hardness or inferior toughness has been a particular drawback experienced in shearing cathodes.
• the steel should be air hardenable in two inch sections to minimize distortion and cracking.
• a shear blade for cutting heavy metal sections should have a yield strength of at least about 290,000 p.s.i., an ultimate strength of at least about 335,000 p.s.i., a Charpy C-notch toughness of at least about 120 foot-pounds at room temperature, a reduction of area of about 25%, a notch tensile strength of at least about 200,000 p.s.i., an
• Another object of this invention is to provide a tool steel characterized by a highly satisfactory combination of strength, ductility, toughness, and hardness.
• Still another object of this invention is to provide a steel shear blade characterized by a good combination of shock and wear resistance.
• shock resisting steels of the following composition based on weight percent: about 0.40% to 0.50% carbon, about 0.2% to 0.8% manganese, about 2.3% to 3.8% silicon, about 2.4% to 3.8% nickel, from 0.25% to 1.8% chromium, about 0.3% to 0.7% molybdenum, the molybdenum content being at least 0.4%, e.g., at least 0.45%, when the chromium is less than 0.5%, about 0.07% to 0.3% vanadium, and the balance essentially iron with residual impurities.
• the carbon should not be less than about 0.40%, and preferably not below about 0.42%, e.g., about 0.45%, to maintain adequate strength. Carbon contents above about 0.50%, and even above about 0.49%, result in a loss in toughness without a useful increase in strength.
• Manganese is added for good steel making practice and should be present in amounts of about 0.2% to 0.8%, and preferably not more than about 0.5%, e.g., about 0.3% to 0.5%, e.g., about 0.35%, to avoid difiiculty in annealing and reduction in toughness.
• results obtained in respect of alloys of substantially the same composition except for silicon content indicated a drop in notch tensile strength from about 260,000 to 210,000 p.s.i.
• the steel contains about 2.35% to 2.7%, e.g., about 2.5% silicon.
• the minimum amount of nickel is about 2.4% which is necessary to provide the steel with adequate hardenability and sufiicient toughness. Nickel also lowers the critical temperature, reduces decarburization, and promotes a fine austenite grain size by allowing austenitizing treatments to be carried out at lower temperatures. On the other hand, nickel in amounts above about 3.8% cause undesirable amounts of retained austenite to be present in the steel. Advantageously, the nickel should be maintained between about 2.8% and about 3.6%, e.g., about 3.5%. Chromium, particularly in amounts of at least 0.5 contributes to hardenability, retards tempering, provides the steel with resistance to decarburization and helps the steel develop low hardness during annealing.
• chromium can be lowered to 0.25 provided the steels contain at least 0.4% molybdenum. Chromium contents above about 1.8% reduce toughness. For the most advantageous results, therefore, the chromium content should be about 0.8% to 1.7%,
• a minimum molybdenum content of about 0.3% contributes to the hardenability of the steel while amounts above about 0.7% hinder the dissolution of carbides at relatively low austenitizing temperatures.
• the molybdenum should be maintained between about 0.35% and 0.6%.
• Vanadium in amounts of at least about 0.08%, e.g., about 0.1%, assures resistance to grain coarsening at ordinary heat treating temperatures while amounts in excess of about 0.3% lower hardenability at normal hardening temperatures.
• the vanadium content should not exceed about 0.2%.
• the steels of the invention should be austenitized at about 1600 F. to 1700 F., e.g., about 1650 F., quenched, e.g., oil
• the steel is austenitized at about 1650 F. for about 1 hour, oil quenched, refrigerated, e.g., below about minus 100 F. or lower for about 1 hour, and double tempered at about 600 F. for about 2 hours at each temper. Refrigeration can be conducted below about 32 F. down to at least as low as minus 300 F.
• Shock resisting tool steels of the present invention are suitable for use in a wide variety of applications. They are particularly adaptable for use as shear blades for cutting heavy metal sections such, for example, as nickel cathodes, if refrigerated prior to tempering.
• the steels of this invention can be commercially prepared by conventional methods for making tool steels.
• the term, balance when used to indicate the amounts of iron in the alloy steels, does not exclude the presence of other elements commonly present as incidental elements, e.g., deoxidizing and cleaning elements, and impurities ordinarily associated therewith, in small amounts which do not adversely affect the basic characteristics of the steels.
• a steel consisting of about 0.40% to 0.50% carbon, about 0.2% ⁇ to 0.8% maganese, about 2.3% to 3.8% silicon, about 2.4% to 3.8% nickel, about 0.25% to 1.8% chromium, about 0.3% to 0.7% molybdenum, provided that the molybdenum content is at least 0.4% when the chromium content is less than 0.5%, about 0.07% to 0.3% vanadium, the balance consisting essentially of iron.
• a steel in accordance with claim 1 which contains at least 0.5 chromium and up to 0.15% aluminum.
• a shock resisting steel according to claim 1 having at least about 280,000 p.s.i. yield strength, at least about 325,000 p.s.i. ultimate strength, at least about 5% elongation, a Charpy C-notch toughness of at least about foot-pounds, at least about 190,000 p.s.i. notch tensile strength, and at least a hardness of about Re 57 after austenitizing at about 1600 F. to 1700 F. for about 1 hour liquid, quenching, refriegrating below minus F and tempering at least once at about 600 F. for about 2 hours.
• a steel in accordance with claim 5 which contains 0.5% chromium and up to 0.15% aluminum.
• a steel in accordance with claim 5 containing about 0.42% to 0.49% carbon, about 0.3% to 0.5 manganese, about 2.35% to 2.7% silicon, about 2.8% to 3.6% nickel, about 0.8% to 1.7%: chromium, about 0.35% to 0.6% molybdenum, and about 0.1% to 0.2% vanadium.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Heat Treatment Of Articles (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24450556

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Citations (4)

• 1967
  • 1967-01-26 US US611828A patent/US3489552A/en not_active Expired - Lifetime
• 1968
  • 1968-01-01 GB GB73/68A patent/GB1142236A/en not_active Expired
  • 1968-01-25 FR FR1551809D patent/FR1551809A/fr not_active Expired
  • 1968-01-26 BE BE709975D patent/BE709975A/xx unknown

Patent Citations (4)

Also Published As

Similar Documents