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.degree. C. to about 1,070.degree. 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.degree. C. to 350.degree. C. and below approximately 700.degree. C., in particular below the Curie point of iron, and with at least 5%, preferably at least 12% deformation.

Dependencies are inferred from the claim text.