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Comparative studies are provided for cryogenic austenitic steels. All of the steels studied may be used as cryogenic materials with increased strength. A new economic low-nickel steel Cr19Ni6Mn10Mo2N has the highest strength level in hot-rolled and cold-rolled conditions from the austenitic condition region, and this provides effective use within the Arctic and Antarctic climatic regions. This steel has a stable austenitic structure and quite good mechanical properties from +100 to -170°C and at these temperatures may replace highly alloyed steel type Cr22Ni16Mn7N. Traditional steel Cr19Ni9N may only be used as cryogenic material for undeformable objects since below 70°C strain-induced martensite may form within it. [ABSTRACT FROM AUTHOR]

Corrosion tests are performed on developed chromium corrosion-resistant steels alloyed with nitrogen. A set of tests shows that depending on chemical composition and production parameters the corrosion resistance indices for steels of one class may differ by an order of magnitude. Revelation of a dependence makes it possible to conclude that an increase within steel of nitrogen and molybdenum content combined with quenching and low-temperature tempering at 400°C makes it possible to prepare steel with good pitting corrosion resistance in aqueous media, particularly, under sea water conditions. [ABSTRACT FROM AUTHOR]

In this study, the influence of cyclic strain amplitude on the evolution of cyclic stress-strain response and the associated cyclic deformation mechanisms in 316LN stainless steel with varying nitrogen content (0.07 to 0.22 wt pct) is reported in the temperature range 773 K to 873 K (500 °C to 600 °C). Two mechanisms, namely dynamic strain aging and secondary cyclic hardening, are found to strongly influence the cyclic stress response. Deformation substructures associated with both the mechanisms showed planar mode of deformation. These mechanisms are observed to be operative over certain combinations of temperature and strain amplitude. For strain amplitudes >0.6 pct, wavy or mixed mode of deformation is noticed to suppress both the mechanisms. Cyclic stress-strain curves revealed both single and dual-slope behavior depending on the test temperature. Increase in nitrogen content is found to increase the tendency toward planar mode of deformation, while increase in strain amplitude leads to transition from planar slip bands to dislocation cell/wall structure formation, irrespective of the nitrogen content in 316LN stainless steel. [ABSTRACT FROM AUTHOR]

Influence of nitrogen content on low cycle fatigue life and fracture behavior of 316LN stainless steel (SS) alloyed with 0.07 to 0.22 wt pct nitrogen is presented in this paper over a range of total strain amplitudes ( ±0.25 to 1.0 pct) in the temperature range from 773 K to 873 K (500 °C to 600 °C). The combined effect of nitrogen and strain amplitude on fatigue life is observed to be complex i.e., fatigue life either decreases/increases with increase in nitrogen content or saturates/peaks at 0.14 wt pct N depending on strain amplitude and temperature. Coffin-Manson plots (CMPs) revealed both single-slope and dual-slope strain-life curves depending on the test temperature and nitrogen content. 316LN SS containing 0.07 and 0.22 wt pct N showed nearly single-slope CMP at all test temperatures, while 316LN SS with 0.11 and 0.14 wt pct N exhibited marked dual-slope behavior at 773 K (500 °C) that changes to single-slope behavior at 873 K (600 °C). The changes in slope of CMP are found to be in good correlation with deformation substructural changes. [ABSTRACT FROM AUTHOR]

High-nitrogen steels are finding increasing use in the industrially developed nations. However, they are still not being used to their full potential. Among the reasons are the time and money needed to develop new grades of high-nitrogen steels. This article reports on the progress made in this area by the Institute of Metallurgy of the Bulgarian Academy of Sciences. As an example, it describes the quick and efficient process followed in developing a new nickel-free low-manganese austenitic stainless steel obtained by refining in the suspended state under pressure. [ABSTRACT FROM AUTHOR]

Focuses on the use of high nitrogen alloyed steels for nonmagnetic drill collars in the oil field industry. Applications of nonmagnetic drill collars; Chemical composition of chromium-manganese-nitrogen steels for drill string components; Manufacture of nonmagnetic drill collars.