Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C37/00—Cast-iron alloys

Definitions

• the present invention relates to improved alloyed cast iron, preferably alloyed gray cast iron.
• alpha (a) assumes a value of approximately 1.05 10- for a gray cast iron produced under normal conditions (cf. A. Collaud, lecture given during the International Foundry Congress in Zurich, Switzerland, 1960).
• inoculants By employing different treating processes, for instance, by the addition of inoculants, it is possible to obtain higher value of alpha (or), that is, with given values of E and A to increase the tensile strength, so that alpha (or) can be considered a quality characteristic.
• Another important object of this invention is to produce a gray cast iron of improved properties.
• This alloy also possesses the good casting properties of a conventional cast iron.
• the manganese content should be reduced as much as possible, or, better still, completely avoided; however, such as not possible becouse the manganese has the function of completely or partially binding the present sulphur because it is an exceptionally strong carbide stabilizer.
• the following rule of thumb is known:
• preferably 3 sulphur percent still possesses a toughness which lies above that of conventional gray cast iron, in addition thereto, however, possesses an increased wearibility and hardness with concurrent good workability.
• alloyed cast irons the analysis of which indicates a Mn/S-ratio beneath 5:1 still correspond to those with a ratio of above 5:1, they are, therefore, also alloyed cast irons with maximum toughness.
• a pig iron suitable especially for the purpose of the present invention it is possible, for example, to start from a pig iron suitable especially for the purpose of the present invention and to correct such to the desired terminal analysis in a suitable, preferably electrically-heated furnace having a slag blanket or a furnace cover in order to completely enclose the furnace proper.
• a tough gray cast iron produced according to the present invention can be employed in the as-cast condition as well as also after a heat-treatment.
• the element should not possess any or only a weak carbide stabilizing effect, since otherwise the silicon content must be increased.
• the element should be completely soluble n the range of use in the iron also in solid condition, without forming a bond and should possess a lattice constant similar to iron (2.87 A.), so that there is considerably avoided a distortion of the ferrite lattice.
• a certain quantity of silicon is required for the gray solidification of tough gray cast iron, even if such quantity is smaller than in comparison with conventional gray cast iron.
• silicon embrittles the iron; it has a lattice ,constant of 5.43 A.
• gray solidification is also enhanced by nickel, even if only approximately one-third as intensive as with silicon. It is possible, therefore, to produce a tough gray cast iron which instead of, for example, -1.0% Si contains approximately 2.4% Ni and only 0.2% Si.
• tough gray cast iron according-to the invention is not characterized by tensile strength, hardness and modulus of elasticity, rather by its dynamic and static energy of fracture as *Well as its impact modulus, the values of which are 2 to 3 times higher thanthose of a commercial gray iron of good quality.
• Striking examples for the useful application of the improved heat conductivity in combination with the actual exceptional toughness of the tough gray cast iron in comparison to conventional cast iron are the production of iron molds, rollers, special steel mill cast iron molds and rolling mill rollers. It was already desirable for some time to replace the previously employed hematite casting by a material possessing greater toughness, in order that such would be in a position to reduce thermal stresses by plastic deformation.
• the high heat conductivity of the tough gray cast iron prevents the appearance of thermal stresses and the good toughness is sufficient to reduce stresses still appearing without, however, being so great that it is necessary to fear a change of form.
• the cast iron molds of steel mills generally possess approximately the following analysis: C, 3.2/ 3.8%; Si, 1.5/2.2%; Mn, O.5/1.2%; P, 0.15%; S, 0.10%; they would be cast from a tough gray cast iron with the following composition:
• EXAMPLE 7 There will subsequently be given an example of an alloy before and after inoculation in which there is provided a high nickel content and instead a lower silicon content. As the table clearly points out, the mechanical properties in the as-cast condition are excellent.
• the carbon content of the cast iron hereof can generally range from about 2.5 to about 3. 8 percent.
• An alloyed gray cast iron for use as a workpiece for cast pieces with lamellar graphite formation, great toughness and high heat conductivity in the cast condition consisting essentially of:
• An alloyed cast iron according to claim 1 wherein an alloying element selected from the group consisting of nickel in an amount of from about 0.5% to 1 percent and molybdenum in an amount of from about 0.5 to 1% and mixtures thereof is added to the alloyed cast iron in order to further increase the strength of said alloyed cast iron.
• An alloyed cast iron according to claim 4 wherein at least a portion of the silicon content of the alloyed cast iron is replaced by nickel in a ratio of approximately 3 parts nickel to 1 part silicon replaced.
• An alloyed cast iron according to claim 1 wherein an alloying element selected from the group consisting of nickel in an amount of from about 0.5% to about 1% and molybdenum in an amount of from about 0.2% to about 0.6%, and mixtures thereof is added to the alloyed cast iron in order to further increase the strength of said alloyed cast iron as well as the heat resistance thereof.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Refuse-Collection Vehicles (AREA)

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Citations (6)

• 0
  • DE DENDAT1250643D patent/DE1250643C2/de not_active Expired
• 1964
  • 1964-11-27 AT AT1002064A patent/AT271533B/de active
  • 1964-11-30 US US414906A patent/US3375103A/en not_active Expired - Lifetime
  • 1964-12-01 NL NL6413931A patent/NL6413931A/xx unknown
  • 1964-12-01 FR FR997006A patent/FR1417489A/fr not_active Expired
  • 1964-12-04 BE BE656638D patent/BE656638A/xx unknown
  • 1964-12-04 JP JP39068164A patent/JPS5021416B1/ja active Pending
  • 1964-12-04 GB GB49557/64A patent/GB1094856A/en not_active Expired
• 1973
  • 1973-07-03 JP JP48074969A patent/JPS5249610B2/ja not_active Expired
• 1974
  • 1974-07-09 SE SE7409044A patent/SE7409044L/sv unknown

Patent Citations (6)

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