SU1076488A1 - Non-magnetic steel - Google Patents

Abstract

NONMAGNETIC STEEL, containing carbon, manganese, nickel, vanadium, iron, is different from the fact that, in order to increase strength and wear resistance, it additionally contains chromium, niobium, calcium, cerium in the following ratio of components, wt.%: 0 4-0.5. Carbon 14.1-18.2. Manganese 3.0-4.0 Nickel 3.2-4.2 Vanadium 1.5-2.5 Chromium 0.03-0.08. Niobium 0,001-0,005 Calcium 0,10-0,20 Cerium Rest Iron (L

Description

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00 The invention relates to metallurgy, in particular to aging high-strength non-magnetic steel, and can be used to make highly loaded non-magnetic parts (including complex shapes and large sections of power and transport engineering operating at high contact loads. Known non-magnetic steel tl3 containing ma s.%: Carbon 0.3-0.43 Manganese 20.5-22.5 Nickel11-13 Vanadium 0.8-1.2 Iron Rest The disadvantage of this steel is low strength properties. Closest to the proposed one as far as possible The effect is aging non-magnetic steel C23f containing, in May.%; Carbon 0.3-0.5 Manganese 14-18 Nickel8-12 Vanadium 0.7-1.7 Iron Else The use of known steel for the manufacture of non-magnetic highly loaded parts working in knots of friction; difficult because its chemical composition and existing methods of hardening nonmagnetic steels do not provide a combination of high mechanical properties, low magnetic permeability ((01 G / e) and good quality nitrided layer Bina more than 0.25 mm. Known steel after hardening heat treatment has a strength level required for highly loaded parts. In addition, in this steel, after nitriding, which is necessary to increase its wear resistance, the low values of the depth and hardness of the nitriding layer do not ensure reliable operation of these parts. The purpose of the invention is to increase the productivity and wear resistance. This goal is achieved by the fact that non-magnetic steel containing carbon, manganese, nickel, vanadium iron, additionally contains chromium niobium, calcium, cerium, with the following ratio of components, wt.% 0.5 Manganese 14.1-18.2 Nickel 3.0-4.0 Vanadium 3.2-4.2 Chromium 1.5-2.5 Niobium 0.03-0.08 Calcium 0.001-0.005 Cerium 0, 1-0.20 Iron Else When the content of vanaschi, niobium and carbon is less than the specified limits. the required hardening of the steel is not achieved, since during its heat treatment a small amount (, 5 wt.%) of reinforcing carbide particles, VC, is formed. The introduction of vanadium, niobium, and carbon in steel in quantities exceeding the established alloying limits leads to high hardening and embrittlement of the steel (test report resulting from the release of a large amount of VC and YHC carbides during the aging process. Additive to steel 0.03-0.08 wt.% niobium, which with carbon forms insoluble carbide cs when heated for quenching, provides a fine-grained structure and almost complete dissolution during tempering of VC carbides, which contributes to increasing the strength of steel after aging and improving the quality of the nitrated layer. The high content of vanadium in steel, which is higher than necessary for its complete binding to carbon, and the addition of chromium in the amount of 1.5-2.5% by mass increase the hardness of the nitrated layer. At isothermal exposures, 5 wt.% Result in the formation of large particles of chromium carbide Me-yCj or MezzS along the grain boundaries, which drastically reduce the ductility of steel. enitnoy structure. After heat treatment (quenching 1170 ° C, aging at 650 ° C for 15 hours, the steel remains nonmagnetic H, 01 G / E, Table 1). Small additives of cerium and calcium in amounts of 0.10-0.20 and 0.0010, 005 wt.%, Respectively, contribute to improving the processability of steel. High ductility at 9001200 0 of this steel provides for the production of various types of stamped and rolled billets using hot rolling or stamping. The steelmaking process does not vary compared with that used for the known steel. Steel is smelted in an open induction furnace and subjected to heat treatment and nitriding to maximize its strength. Table 1 shows the chemical composition of the precipitation hardening steels.

Table 1

After the nitriding, the proposed steel having a heat-treating fine-grained structure is provided with good quality nitrided layer without chipping and chipping.

In the numerator and denominator - the depth of the nitrated layer with a hardness of HNbOO after nitriding in an environment of 80% N + 20 KNz at temperatures of respectively - 30 hours and - 20 hours.

In tab. 2 shows the mechanical properties, magnetic permeability, austenitic grain size dj, pH characteristics of the nitrated steel layer (quenching) from 1170 ° С and aging at 650 ° C and 15 h.

table 2

Nitriding provides the proposed steel with a depth of 0.25. 0.40 mm and hardness 730-870, known - the depth of nitrided SPO 0.15-0.35 mm and hardness NU, 600-630.

Comparative tests of wear resistance and contact strength were carried out on an MI-1M machine with a friction of 1 with a specific slip of 15% on rollers 28.6 mm according to the following procedure. Two rollers of single steel heats 1 and 5 (the composition of which goes beyond the limits of the proposed /. Have low levels of strength ((600 MPa for melting 1 or plasticity and toughness (if 4% and 1.5 kJ / cm for melting 5) that does not ensure reliable operation of high-loaded non-magnetic parts. By strength characteristics, austenitic grain size, depth

rotates at different times at 425 and 360 rpm. At each load, the specimens were tested for 40 hours; at the end of the stage, the wear of the specimens with weight loss was determined.

The received loads on the rollers and the corresponding contact stresses, as well as the value of the total wear after each stage of testing, are given in Table. 3

Table 3 and the quality of the nitrated layer. 2), known steel (melts 6 and 7 are significantly inferior to the proposed steel and cannot be used to manufacture highly loaded non-magnetic parts. The expected economic effect from the use of the proposed steel is 100 thousand rubles a year.

Claims (1)

NONMAGNETIC STEEL containing carbon, manganese, nickel, vanadium, iron, characterized in that, in order to increase strength and wear resistance, it additionally contains chromium, niobium, calcium, cerium in the following ratio, wt.%: Carbon 0.4-0.5 Manganese 14.1-18.2 Nickel 3.0-4.0 Vanadium 3.2-4.2 Chromium 1.5-2.5 Niobium 0.03-0.08 Calcium 0.001-0.005 Cerium 0.10-0.20 Iron Rest h 00 oo one 1076488 2