Method of manufacturing nonmagnetic drilling string components

{
  "publication_number": "US4919728A",
  "country": "US",
  "kind": "A",
  "title": "Method of manufacturing nonmagnetic drilling string components",
  "abstract": "The method of manufacturing nonmagnetic drilling string components, especially heavy duty drill-stems for exploratory bores, e.g. for deposits of crude oil and/or natural gas deposits, such as directional bores or the like, includes the step of melting and allowing to solidify an alloy consisting essentially of, each in percent by weight: carbon in a maximum of 0.15, preferably 0.08; silicon in a maximum of 1.0; manganese 11.0 to 25.0, preferably 12.0 to 20.0; chromium 10.0 to 20.0, preferably 11.0 to 16.0; molybdenum 0.1 to 1.0, preferably 0.2 to 0.8; nickel 0.1 to 6.0, preferably 1.0 to 3.0; nitrogen 0.05 to 0.5, preferably 0.1 to 0.35; and the remainder being iron and impurities resulting from manufacturing conditions. The alloy is subjected to an at least two-stage, especially a four- to six-stage hot-working process and, if desired, cooled down and then solution heat-treated at about 1,020° C. to about 1,070° C. Subsequently, the alloy is quenched, for example, in water and subjected to a cold-working operation. The cold-working operation is carried out at a temperature above the martensite formation temperature, i.e. above the temperature range of 300° C. to 350° C. and below approximately 700° C., in particular below the Curie point of iron, and with at least 5%, preferably at least 12% deformation.",
  "claims": [
    "1. A method manufacturing nonmagnetic heavy duty drilling string components for exploratory and directional bores for crude oil and natural gas deposits, comprising the steps of: melting and allowing to solidify an alloy consisting essentially of, each in percent by weight: carbon in a maximum of about 0.15; silicon in a maximum of about 1.0; manganese about 11.0 to about 25.0; chromium about 10.0 to about 20.0; molybdenum about 0.1 to about 1.0; nickel about 0.1 to about 6.0; nitrogen about 0.05 to about 0.5; the remainder being iron and other impurities resulting from manufacturing conditions; subjecting the alloy to a hot-working operation; solution heat-treating the alloy at temperatures of about 1,020° C. to about 1,070° C.; subsequently quenching the alloy; subjecting the quenched alloy to a cold-working operation at a temperature in the range of above 350° C. to below about 750° C.; and said step of cold-working said alloy entails cold-working to at least 5% deformation.",
    "2. The method as defined in claim 1, further including the step of: selecting as said alloy, an alloy consisting essentially of, each in percent by weight: carbon in a maximum of 0.08; manganese about 12.0 to about 20.0; chromium about 11.0 to about 16.0; molybdenum about 0.2 to about 0.8; nickel about 1.0 to about 2.5; nitrogen about 0.1 to about 0.35, and the remainder being iron and other impurities resulting from manufacturing coniditions.",
    "3. The method as defined in claim 1, wherein: said step of hot-working said alloy entails a hot-working operation resulting in a 2:1 area reduction.",
    "4. The method as defined in claim 1, wherein: said step of hot-working said alloy entails a hot-working operation resulting in a 4-6:1 area reduction.",
    "5. The method as defined in claim 1, further including the step of: cooling said alloy after said hot-working operation and prior to said solution heat treatment.",
    "6. The method as defined in claim 1, wherein: said step of quenching said alloy entails quenching the alloy in water.",
    "7. The method as defined in claim 1, wherein: said step of cold-working is performed at a maxium temperature below the Curie point of iron.",
    "8. The method as defined in claim 1, wherein: said step of cold-working said alloy entails cold-working at a temperature below 550° C.",
    "9. The method as defined in claim 1, wherein: said step of cold-working is performed at a temperature which is above the upper limit of the martensite formation temperature.",
    "10. The method as defined in claim 1, wherein: said step of cold-working said alloy entails cold forging.",
    "11. The method as defined in claim 10, wherein: said cold forging entails stretch forging.",
    "12. The method as defined in claim 1, wherein: said step of cold-working said alloy entails cold-working to at least 12% deformation.",
    "13. The process as defined in claim 1, further including the step of: mechanically processing said alloy following the cold-working operation.",
    "14. The method as defined in claim 13, wherein: said step of mechanically processing said alloy entails machining said alloy.",
    "15. The method as defined in claim 1, further including the steps of: locally cold-working said alloy in marginal regions close to the surface of said alloy at a temperature in the range of above 350° C. to below about 750° C. in order to thereby produce inherent compressive stresses.",
    "16. The method as defined in claim 15, wherein: said step of locally cold-working said alloy entails ball-blasting.",
    "17. The method as defined in claim 16, wherein: said step of locally cold-working said alloy entails cold-working below the Curie point of iron.",
    "18. The method as defined in claim 15, wherein: said step of locally cold-working said alloy entails cold-working at a temperature below 550° C.",
    "19. The method as defined in claim 15, wherein: said step of locally cold-working said alloy entails cold-working at a temperature which is above the upper limit of the martensite formation temperature.",
    "20. A method of manufacturing nonmagnetic heavy duty drilling string components for exploratory and directional bores for crude oil and natural gas deposits, comprising the steps of: melting and allowing to solidify an alloy consisting essentially of, each in percent by weight: carbon in a maximum of about 0.15; silicon in a maximum of about 1.0; manganese about 11.0 to about 25.0; chromium about 10.0 to about 20.0; molybdenum about 0.1 to about 1.0; nickel about 0.1 to about 6.0; niobium/tantalum above 0.1 to about 2.0 nitrogen about 0.5 to about 0.5; the remainder being iron and other impurites resulting from manufacturing conditions; subjecting the alloy to a hot-working operation; solution heat-treating the alloy at temperatures of about 1,020° C. to about 1,070° C.; subsequently quenching the alloy; subjecting the quenched alloy to a cold-working operation at a temperature in the range of about 300° C. to below about 750° C.; and said step of cold-working said alloy entails cold-working to at least 5% deformation.",
    "21. The method as defined in claim 20, further including the step of: selecting as said alloy, an alloy consisting essentially of, each in percent by weight: carbon in a maximum of 0.8; manganese about 12.0 to about 20.0; chromium about 11.0 to about 16.0; molybdenum about 0.2 to about 0.8; nickel about 1.0 to about 2.5; nitrogen about 0.1 to about 0.35, and the remainder being iron and other impurities resulting from manufacturing conditions.",
    "22. The method as defined in claim 20, wherein: said step of cold-working entails cold-working at a temperature in the range of about 300° C. to 400° C.",
    "23. The method as defined in claim 20, wherein: said alloy containing niobium/tantalum in an amount of about 0.4 to 0.8 percent by weight.",
    "24. The method as defined in claim 20, wherein: said step of hot-working said alloy entails a hot-working operation resulting in a 2:1 area reduction.",
    "25. The method as defined in claim 20, wherein: said step of hot-working said alloy entails a hot-working operation resulting in a 4-6:1 area reduction.",
    "26. The method as defined in claim 20, further including the step of: cooling said alloy after said hot-working operation and prior to said solution heat treatment.",
    "27. The method as defined in claim 20, wherein: said step of quenching said alloy entails quenching the alloy in water.",
    "28. The method as defined in claim 20, wherein: said step of cold-working is performed at a maximum temperature below the Curie point of iron.",
    "29. The method as defined in claim 20, wherein: said step of cold-working said alloy entails cold forging.",
    "30. The method as defined in claim 29, wherein: said cold forging entails stretch forging.",
    "31. The method as defined in claim 20, wherein: said step of cold-working said alloy entails cold-working to at least 12% deformation.",
    "32. The process as defined in claim 20, further including the step of: mechanically processing said alloy following the cold-working operation.",
    "33. The method as defined in claim 32, wherein: said step of mechanically processing said alloy entails machining said alloy.",
    "34. The method as defined in claim 20, further including the steps of: locally cold-working said alloy in marginal regions close to the surface of said alloy at a temperature in the range of about 300° C. to below about 750° C. in order to thereby produce inherent compressive stresses.",
    "35. The method as defined in claim 34, wherein: said step of locally cold-working said alloy entails ball-blasting.",
    "36. The method as defined in claim 35, wherein: said step of locally cold-working said alloy entails cold-working below the Curie point of iron.",
    "37. The method as defined in claim 34, wherein: said step of locally cold-working said alloy entails cold-working at a temperature below 550° C.",
    "38. The method as defined in claim 34, wherein: said step of locally cold-working said alloy entails cold-working at a temperature which is at least equal to the upper limit of the martensite formation temperature."
  ],
  "cpc": [
    "C22C 38/38",
    "C21D 8/00"
  ],
  "assignees": [
    "VER EDELSTAHLWERKE AG"
  ],
  "filing_date": "1988-07-15",
  "publication_date": "1990-04-24",
  "grant_date": "1990-04-24",
  "priority_date": "1985-06-25",
  "application_number": "US-21921688-A",
  "family_id": "3522989",
  "citations": [
    "US4472207A"
  ]
}