RU2360029C1 - High-strength nonmagmetic composition steel - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field, particularly to composition of high-strength non-magnetic corrosion-resistant composition steel, used in mechanical engineering, aircraft building, special shipbuilding, instrument making and at creation of high-performance drilling engineering. Steel contains carbon, silicon, manganese, chrome, nickel, nitrogen, niobium, molybdenum, vanadium, zirconium nitride, iron and unavoidable admixtures at following ratio of components, wt %: carbon 0.04 - 0.12, silicon 0.10 - 0.60, manganese 5.0 - 12.0, chrome 19.0 - 21.0, nickel 4.0 - 9.0, molybdenum 0.5 - 1.5, vanadium 0.10 - 0.55, niobium 0.03 - 0.30, nitrogen 0.4 - 0.7, zirconium nitride 0.03 - 1.00, iron and unavoidable admixtures are the rest. Zirconium nitride is in the form of particles with nano-dispersibility.

EFFECT: there are increased strength properties of steel at simultaneous increasing of plasticity and viscosity index.

2 cl, 2 tbl, 1 ex

Description

The invention relates to the field of metallurgy and can be used in mechanical engineering, aircraft manufacturing, special shipbuilding, instrument making and for creating highly efficient drilling equipment.

Known non-magnetic steel of the following chemical composition, wt.%: Carbon 0,01-0,05; chrome 21.0-24.0; manganese 12.0-15.0; nickel 1.0-8.0; nitrogen 0.65-0.80; molybdenum 0.5-1.0; vanadium 0.25-1.0; calcium 0.0015-0.020; the rest is iron (Auth. St. USSR No. 1225876, M. cl. C22C 38/58, publ. 04/23/1986).

The disadvantage of steel is the insufficiently high characteristics of ductility and toughness and the development of intergranular corrosion due to the presence of vanadium in the steel, which, when combined with nitrogen and carbon, forms vanadium nitrides and carbides, which precipitate during solidification along the boundaries of austenitic grains. In addition, vanadium as a ferrite-forming element promotes the release of the ferromagnetic phase (δ - ferrite), increasing the magnetic permeability.

The closest in technical essence and the achieved result is a high-strength non-magnetic corrosion-resistant welded steel of the following chemical composition, wt.%: Carbon 0.04-0.9, silicon 0.10-0.60, manganese 5.0-12.0 chromium 19.0-21.0, nickel 4.5.0-9.0, molybdenum 0.5-1.5; vanadium 0.10-0.55; calcium 0.005-0.010; niobium 0.03-0.30, nitrogen 0.40-0.70; inevitable impurities and iron rest. In this case, for the values of the concentration of alloying elements, the condition is satisfied:

[Ni] +0.1 [Mn] -0.01 [Mn] ² +18 [N] +30 [C] / [Cr] + l, 5 [Mo] +0.48 [Si] +2.3 [V] + l, 75 [Nb] = 0.70-0.90,

where [N], [C], [Si], [Mn], [Ni], [Cr], [Mo], [V], [Nb] is the concentration in the steel of nitrogen, carbon, silicon, manganese, nickel, chromium, molybdenum, vanadium and niobium, respectively, expressed in mass percent. The ratio of carbon to nitrogen is 0.05-0.15.

In addition, steel has a developed subgrain structure after hot plastic deformation at a temperature of 1000-1050 ° C with compression of 50-80% and subsequent cooling in water to room temperature.

The steel has a fine-grained austenitic structure after quenching in water from a temperature of 1030-1070 ° C (RF Patent No. 2205889, M. C. C22C 38/58, publ. 06.10.2003, prototype).

The disadvantage of this steel is the insufficiently high characteristics of ductility and toughness of steel, since the presence of strong carbide and nitride-forming elements of niobium and vanadium will lead to the release of large-sized both carbides and niobium and vanadium nitrides along the boundaries of austenitic grain during steel hardening, which will reduce the ductility and viscosity.

The problem solved by the invention is the production of steel with high strength properties with high ductility and toughness.

This problem is solved in that the high-strength non-magnetic corrosion-resistant composite steel, including carbon, silicon, manganese, chromium, nickel, nitrogen, niobium, molybdenum, vanadium, iron, additionally contains zirconium nitride in the following ratio of components, wt.%:

Carbon 0.04-0.12 Silicon 0.10-0.60 Manganese 5.0-12.0 Chromium 19.0-21.0 Nickel 4.0-9.0 Molybdenum 0.5-1.5 Vanadium 0.10-0.55 Niobium 0.03-0.30 Nitrogen 0.4-0.7 Zirconium nitride 0.03-1.00 Iron and impurities rest

Steel contains zirconium nitride in the form of particles with nanoscale dispersion.

The introduction of finely dispersed zirconium nitrides with nanoscale dispersion into the composition of the steel will allow the formation of a large number of crystallization centers uniformly distributed in the metal volume.

During solidification, chemically resistant particles of zirconium nitride, being in a highly nitrogenous melt, have increased resistance to dissociation and will be inoculators, centers of crystallization of austenitic grains, which will substantially grind the primary austenitic grain, increase the area of the boundaries of austenitic grains, and also increase the speed of solidification of castings. This will significantly reduce the amount and increase the dispersion of vanadium and niobium carbides and nitrides that precipitate along the boundaries of austenitic grains, which ultimately will lead to an increase in strength properties and at the same time ductility and viscosity.

When the content of finely dispersed zirconium nitrides in steel in an amount of less than 0.03 wt.% Does not increase the strength properties, since there is no sufficient grinding of grain and stabilization of grain boundaries.

When the content of zirconium nitrides is more than 1.00 wt.%, The plasticity and viscosity characteristics deteriorate, since zirconium nitrides begin to be released in excess in grain boundaries.

Thus, the technical result of the invention is to increase the strength properties of steel while increasing ductility and toughness.

Example.

Steel was smelted in an open main induction furnace with a capacity of 160 kg by fusing stainless nitrogen-containing wastes and pure ferroalloys. Nitrogen was introduced into the composition of steel with nitrided wastes and nitrided ferroalloys of chromium and manganese.

Zirconium nitride was obtained by the SHS method of filtration combustion. After nitriding, the zirconium nitride cake was crushed and ground to a fraction of less than 100 nm in a ball mill for 5 minutes. Zirconium nitride was introduced in metal capsules per stream of metal when melting was released into the ladle. Metal was poured on top into ingots weighing 130 kg and a diameter of 150 mm. The ingots were heated in a gas furnace to a temperature of 1175-1220 ° C and forged at a temperature of at least 1050 ° C onto bars with a section of 70 × 70 mm. Longitudinal tensile and shock bending samples were made from rods, which were subjected to heat treatment by quenching in water from 1050 ° С.

The metal structure was studied using a Neofot-2 metallographic microscope.

The phase composition of the steel was determined on a DRON-3M X-ray diffractometer.

Mechanical tensile tests according to GOST 1497-80 were carried out on a Type 1958u-10 universal testing machine, and impact bending tests were carried out on a KM-30 pile head according to GOST 9454-80.

The results of the chemical analysis of the proposed steel are given in table 1.

The test results are presented in table.2.

According to the test results, it is evident that the proposed steel has higher strength characteristics with increased ductility and viscosity characteristics, which will lead to increased durability of products from this metal.

Table 1. The chemical composition of steel Melting The content of elements, wt.% FROM Si Mn Cr Ni Mo V Nb Sa N Zrn S P Fe and impurities one 0.04 0.10 5,0 19.0 4.0 0.5 0.10 0,03 - 0.4 0,03 0.006 0.018 Ost. 2 0.09 0.30 10.0 20.5 8.0 0.9 0.35 0.10 - 0.55 0.50 0.007 0.019 Ost. 3 0.12 0.58 11.8 21.0 8.9 1,5 0.55 0.30 - 0.69 1.00 0.011 0,020 Ost. four 0.08 0.25 11,2 20.3 8.73 0.87 0.40 0.20 - 0.57 0.02 0.009 0.17 Ost. 5 0.04 0.40 11.0 19.6 8.5 1,0 0.45 0.15 - 0.70 1,1 0.006 0.018 Ost. 6 prototype 0.4 0.26 11.7 19.9 5,6 1,5 0.37 0.27 0.006 0.51 - 0.004 0.017 Ost.

table 2 Mechanical properties and magnetic permeability of steel Melting σ _B, MPa σ _0.2, MPa δ,% ψ,% KCU, MJ / m ² µ, G / E one 1170 1132 59 78 4.3 1.001 2 1180 1150 53 75 3.8 1.002 3 1200 1160 fifty 75 3,1 1.001 four 900 850 fifty 68 1,2 1.004 5 1180 1100 35 fifty 1,0 1.005 6 prototype 1040 848 32 55 2.2 1.005

Claims (2)

1. High-strength non-magnetic corrosion-resistant composite steel containing carbon, silicon, manganese, chromium, nickel, nitrogen, niobium, molybdenum, vanadium, iron and inevitable impurities, characterized in that it additionally contains zirconium nitride in the following ratio of components, wt.%:
carbon 0.04-0.12 silicon 0.10-0.60 manganese 5.0-12.0 chromium 19.0-21.0 nickel 4.0-9.0 molybdenum 0.5-1.5 vanadium 0.10-0.55 niobium 0.03-0.30 nitrogen 0.4-0.7 zirconium nitride 0.03-1.00 iron and inevitable impurities rest 2. Steel according to claim 1, characterized in that it contains zirconium nitride in the form of particles with nanoscale dispersion.