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 a cast iron with a high phosphorus content intended in particular for the manufacture of friction braking devices, offering good resistance to wear and composed of the following constituents: 85 to 95% by weight of iron 2 to 10% by weight of phosphorus less than 6% of the total weight of carbon and silicon less than 5% of the total weight of the following metals: manganese, cobalt, nickel, vanadium, tungsten and molybdenum, and having a Brinell hardness of less than 270 HB.
• the cast iron according to the invention can be used in devices involving cast iron parts subjected to friction wear, in particular friction brake shoes intended to equip railway equipment.
• Belgian patent No. 717,428 discloses iron / phosphorus alloys which, thanks to their resistance to wear, can be used in friction braking devices.
• the addition of at least 2% by weight of phosphorus reduces friction wear compared to that of conventional gray cast iron as well as reducing the emission of sparks during braking.
• This phosphorus is generally added to cast iron in the form of ferro-phosphorus.
• the incorporation is carried out during a second melting in a cupola in which alternating charges of coke and of a mixture of iron and ferro-phosphorus are previously put in place.
• the cast iron thus obtained has a Brinell hardness of between 207 and 255 HB, while the ferrite content of the alloy is not specified.
• Phosphorus promotes the segregation of graphite and gives rise to the formation of a ternary eutectic, steadite, which has a Brinell hardness of approximately 440 HB. Its melting point is around 950 ° C. Steadite has a much higher hardness than that of ferrite or even perlite.
• ferrite has a Brinell hardness of approximately 125 HB and perlite a Brinell hardness of approximately 220 HB.
• the value of the maximum hardness of cast iron has been fixed to take account of the usual hardness of the wheel treads of rolling stock.
• Document FR-A-2,145,607 describes alloys of cast iron with a characteristic microstructure comprising phosphorus present in the form of a substantially continuous network of a degenerate phosphorus eutectic between voluminous primary dendrite crystals.
• the degenerate eutectic comprises a substantially continuous matrix of iron predominantly in the form of ferrite or perlite.
• This process provides a relatively low hardness ferritic iron.
• it is therefore necessary to carry out an annealing which is obtained by prolonged heating for 1 to 6 hours of the parts cast at a temperature between 850 and 1,500 ° C., preferably 910 to 920 °. vs.
• the limitation of the ferrite content is linked to a phenomenon of micro-welding between the ferritic structure of the brake shoe and that of the wheel tread, this which has the effect of causing premature wear of said wheel tread.
• the invention proposes a cast iron with a high phosphorus content intended in particular for the manufacture of devices friction brake, offering good resistance to wear, and composed of the following constituents: 85 to 95% by weight of iron 2 to 10% by weight of phosphorus less than 6% of the total weight of carbon and silicon less than 5% of the total weight of the following metals: manganese, cobalt, nickel, chromium, tungsten and molybdenum, and having a Brinell hardness of less than 270 HB.
• the production of a pig iron corresponding to the preceding paragraph is carried out by adding ferro-phosphorus to the liquid pig iron collected in a ladle or a mixer and not in the melting installation.
• the direct incorporation of ferro-phosphorus into the ladle also makes it possible to obtain better accuracy of analysis of the phosphorus content.
• the cast irons according to the invention with a phosphorus content of between 2 and 10% by weight and a carbon content of at least 3% by weight, meet the hardness and ferrite content requirements.
• the cast iron contains at least 2.3% by weight of carbon in the form of lamellar graphite.
• Cast iron generally has the following typical composition: carbon: 3 to 4% by weight silicon: 1 to 3% by weight manganese: 0.4 to 1.0% by weight phosphorus: 0.1 to 1.0% by weight sulfur: 0.08 to 0.15% by weight.
• cupola fusion is accompanied by the incorporation of ferro-phosphorus when it comes to obtaining a wear-resistant ferrous alloy.
• the present invention suggests subjecting the cast iron to a different treatment.
• Undissolved iron therefore does not participate in the dilution of carbon, so that the carbon content decreases to a lesser extent than what could have been theoretically predicted and that it remains greater than 3%.
• ferro-phosphorus is adjusted so as to bring the phosphorus content to a value between 2.25 and 4.00% by weight.
• the alloy has a composition typically corresponding to gray cast iron, except as regards the high phosphorus content, greater than 2% by weight and a ferrite content less than 5% by volume.
• the cast iron according to the invention is perfectly suitable for the manufacture of brake shoes for railway equipment. It has excellent wear resistance, as described in Belgian Patent No. 717,428 and considerably reduces the formation of sparks. It also reduces noise emission, since the graphite slats help to dampen the propagation of vibrations in the brake shoes.
• the cast iron according to the invention has good flowability, due to the presence of phosphorus. It therefore allows relatively complicated parts to be produced with precision.

Landscapes

• 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)
• Braking Arrangements (AREA)
• Meat, Egg Or Seafood Products (AREA)
• Lubricants (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (4)

Family

ID=3882504

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (1)

Family Cites Families (8)

• 1987
  • 1987-02-05 BE BE8700085A patent/BE1000292A3/fr not_active IP Right Cessation
• 1988
  • 1988-01-14 DE DE8888870003T patent/DE3872262T2/de not_active Expired - Lifetime
  • 1988-01-14 EP EP88870003A patent/EP0277931B2/de not_active Expired - Lifetime
  • 1988-01-14 ES ES88870003T patent/ES2032602T5/es not_active Expired - Lifetime
  • 1988-01-14 AT AT88870003T patent/ATE77658T1/de not_active IP Right Cessation
  • 1988-02-04 NO NO880496A patent/NO170989C/no not_active IP Right Cessation
  • 1988-02-04 DK DK198800564A patent/DK173189B1/da not_active IP Right Cessation
• 1992
  • 1992-09-14 GR GR920402030T patent/GR3005698T3/el unknown
• 2000
  • 2000-11-08 GR GR20000402481T patent/GR3034788T3/el not_active IP Right Cessation

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