RU2631063C1 - Method of manufacture of instrumental high-strength flats - Google Patents

Method of manufacture of instrumental high-strength flats Download PDF

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RU2631063C1
RU2631063C1 RU2016119835A RU2016119835A RU2631063C1 RU 2631063 C1 RU2631063 C1 RU 2631063C1 RU 2016119835 A RU2016119835 A RU 2016119835A RU 2016119835 A RU2016119835 A RU 2016119835A RU 2631063 C1 RU2631063 C1 RU 2631063C1
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steel
strength
temperature
high
properties
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RU2016119835A
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Russian (ru)
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Михаил Витальевич Чукин
Павел Петрович Полецков
Марина Сергеевна Гущина
Галина Андреевна Бережная
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Открытое акционерное общество "Магнитогорский металлургический комбинат"
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    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHER TREATMENTS
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHER TREATMENTS
    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/42Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for armour plate
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

Abstract

FIELD: metallurgy.
SUBSTANCE: method involves making of steel containing the following components, wt %: 0.20-0.38 C, 0.20-1.10 Si, 0.50-1.00 Mn, 0.50-1.45 Cr, 0.70-1.30 Ni, 0.20-0.80 Mo, 0.02- 0.16 V, 0.02-0.08 Al, 0.001-0.010 N, not more than 0.25 Cu, 0.001-0.030 Nb, 0.001-0.020 Ti not more than 0.008 S, not more than 0.013 P, the rest is Fe, production of continuous-cast slab, its hot deformation, water hardening at a temperature of 930-980°C, tempering at a temperature of 575±25°C. In order to increase the hardening capability, boron (0.001-0.005, is added to the steel composition wt %).
EFFECT: providing high strength properties and hardness while maintaining sufficient plasticity and toughness.
2 cl, 4 tbl

Description

The invention relates to ferrous metallurgy, in particular to the production of tool high-strength sheet metal for high-precision engineering equipment.

High-strength tool steel should have the following properties: increased wear resistance (hardness), the ability to maintain its properties at elevated temperature conditions (heat resistance), high impact strength, low residual stresses, high thermal conductivity, and a high level of crack resistance. Technical characteristics of high-strength tool steel are given in table 1.

Known tool steel containing carbon, silicon, manganese, chromium, titanium, boron, aluminum, copper and iron in the following ratio (wt.%): Carbon 0.04-0.06; silicon 0.04-0.06; manganese 8.0-12.0; chrome 8.0-12.0; titanium 2.0-3.0; boron 0.04-0.06; aluminum 0.4-0.6; copper 0.5-1.0; iron the rest. Steel can be smelted in induction vacuum furnaces. Heat treatment of steel is carried out according to the tempering regime at 750-900 ° C for 2 hours, oil quenching at 1200 ° C (RF Patent No. 2332515, IPC C22C 38/38, publ. 08.28.2008, Bull. No. 24).

The disadvantages of the known steel are that it has insufficient hardness and a fairly high carbon equivalent, which significantly complicates the processes of welding and assembly of finished products.

Known knife for cutting metal from alloy steel containing carbon, silicon, manganese, molybdenum, vanadium, nickel, chromium, sulfur, phosphorus and iron, characterized in that it is made of steel containing these components in the following ratio, mass. %: carbon 0.50-0.60; silicon 0.10-0.40; manganese 0.40-0.70; molybdenum 0.60-0.80; vanadium 0.30-0.60; nickel 1.70-2.00; chrome 1.00-1.30; sulfur not more than 0.005; phosphorus no more than 0.01; iron the rest. After quenching from 920 ° C and subsequent tempering at 450 ± 10 ° C, the knife has a uniform structure with a grain size of 5-8 points, impact strength 39 J / cm 2 and hardness 51 HRC (RF Patent No. 2409696, IPC C22C 38 / 46, published on January 20, 2011, Bull. No. 2).

A disadvantage of the known knife is the relatively low strength properties and relatively high carbon equivalent, which negatively affects the welding properties of steel.

The closest analogue to the present invention is tool steel for hot deformation, containing carbon, chromium, manganese, vanadium, silicon, titanium, boron and iron in the following ratio (wt.%): Carbon 0.60-0.70; chrome 2.80-3.20; manganese 1.9-2.1; vanadium 0.50-0.60; silicon 0.40-0.70; titanium 0.15-0.30; boron 0.001-0.003; iron is the rest, while the total content of chromium, manganese, vanadium, silicon, titanium and boron is 5.35-6.20 mass. % The heat treatment of steel was carried out according to the regime: quenching 1050 ± 50 ° C, with preheating at a temperature of 800 ± 10 ° C; holding time at heating and quenching temperatures for 30 minutes; tempering of steel was carried out at a temperature of 550 ± 5 ° C, holding for 2 hours; air cooling (RF Patent No. 2535148, IPC C22C 38/38, publ. 10.12.2014, Bull. No. 34).

The disadvantage of the prototype is that the known steel after hardening and high temperature tempering has low plastic properties and a relatively high carbon equivalent, which negatively affects the welding properties of steel.

The technical result of the invention is to achieve high hardness tool high-strength sheet metal while maintaining sufficient ductility and toughness.

The specified technical result is achieved by the fact that in the method for the production of tool high-strength sheet metal, including steelmaking, obtaining a continuously cast slab, its hot deformation, hardening and tempering of sheets, according to the invention, steel is melted of the following chemical composition, wt. %: 0.20-0.38 C; 0.20-1.10 Si; 0.50-1.00 Mn; 0.50-1.45 Cr; 0.70-1.30 Ni; 0.20-0.80 Mo; 0.02-0.16 V; 0.02-0.08 Al; 0.001-0.010 N; not more than 0.25 Cu; 0.001-0.030 Nb; 0.001-0.020 Ti; not more than 0.008 S; not more than 0.013 P; the rest is Fe, while the hardening of sheets of the specified steel is carried out at a temperature of 930-980 ° C, tempering is carried out at a temperature of 575 ± 25 ° C. The steel composition additionally contains boron in the range of 0.001-0.005, mass. %

The essence of the invention lies in the fact that the complex of mechanical and functional properties of tool high-strength sheet metal is due to its chemical composition and temperature conditions of heat treatment: quenching and tempering. In order to achieve the required properties (Table 1), during the experimental studies, all significant factors were varied, achieving stable production of high strength characteristics of tool steel while maintaining a fairly high ductility and toughness.

Carbon and chromium - reinforcing elements, directly affect the interval of existence of δ-ferrite, which allows homogenizing a solid solution, increasing the uniformity of the distribution of chemical elements due to the fact that the diffusion mobility of carbon and chromium atoms in δ-ferrite is several orders of magnitude higher than the rate of their diffusion in austenite . A carbon content of less than 0.20% leads to a decrease in strength properties below an acceptable level. An increase in carbon content of more than 0.38% affects the plastic and viscosity properties of steel, increases the carbon equivalent. When the chromium concentration is less than 0.50%, the strength properties do not reach the required values. An increase in the chromium content of more than 1.45% leads to a loss of ductility and an unjustified increase in cost.

Manganese, silicon, nickel, copper and molybdenum are alloying elements that make up austenite solid solution and lower the temperature at which its decomposition begins. When the manganese content is less than 0.5%, the strength of the steel is insufficient. An increase in manganese content of more than 1.0% contributes to the enlargement of grain, reducing the toughness of hardened steel. When the silicon content is less than 0.20%, the deoxidation of steel deteriorates. An increase in the silicon content of more than 1.1% leads to embrittlement of the grain boundaries and the effect on the α phase: martensite and bainite. With a nickel content of less than 0.70%, ductility and toughness are reduced. An increase in the nickel content of more than 1.30% leads to an increase in prime cost, all other things being equal. The addition of molybdenum in the specified range helps to obtain the required strength characteristics of steel, and also improves its hardenability. When the molybdenum content is less than 0.20%, the strength properties of steel do not reach the required level, and an increase in its content of more than 0.80% affects the weldability and ductility of hardened steel. The addition of copper in an amount not exceeding 0.25% helps to achieve the necessary properties. A higher copper content is not economically feasible.

Sulfur and phosphorus are harmful impurities, due to their reduced solubility in ferrite, they diffuse to the grain boundaries, affecting the quantity and quality of the “nuclei” —the site of formation of the ferrite phase. With a content of more than 0.008% and 0.013%, respectively, they have a sharply negative effect on the viscosity properties of steel.

Aluminum deoxidizes and modifies steel. At a concentration of less than 0.02%, its effect is weak, which affects the mechanical properties. An increase in its content of more than 0.08% graphitizes carbon, which also impairs mechanical properties.

Nitrogen promotes the formation of nitrides in steel. The upper limit of nitrogen content - 0.010% is due to the need to obtain a given level of ductility and toughness of steel, and the lower limit - 0.001% - to questions of manufacturability.

Vanadium, niobium and titanium - carbon-nitride-forming elements form a solid substitution solution with iron. The mismatch of the atomic radii of these elements and iron leads to a distortion of the crystal lattice of the solid solution and, as a result, to a slowdown of all processes controlled by diffusion, including recrystallization and phase transformations. A vanadium content of more than 0.16% leads to a deterioration in the weldability of steel and is not economically feasible due to the increase in alloying costs. When the content of vanadium is less than 0.02%, the strength properties of steel do not reach the required level. When the niobium content is less than 0.001%, sufficient hardening is not provided. An increase in the niobium content of more than 0.030% leads to a deterioration in the weldability of steel and is not economically feasible in view of the increase in alloying costs. A titanium content of less than 0.001% does not have a deterrent effect on the growth of austenitic grain, and strength decreases. An increase in the titanium content in excess of 0.020% is impractical, since it leads to the formation of coarse inclusions of highly hard, brittle titanium carbide during crystallization, which is not eliminated by heat treatment and reduces the toughness.

Alloying with boron increases the strength properties after hardening, without changing the viscosity and ductility. Boron, added in the range of 0.001-0.005%, significantly increases the hardenability of steel. Boron in an amount of more than 0.005% contributes to embrittlement of steel. A boron content of less than 0.001% does not have a positive effect on the properties of steel.

Heating under quenching to temperatures above 980 ° C leads to a significant reduction in the toughness of tool steel. Lowering this temperature to less than 930 ° C does not provide stable production of desired strength properties, which significantly reduces the yield.

Vacation at temperatures above 600 ° C reduces the strength properties below the permissible level. A decrease in tempering temperature below 550 ° C results in a loss of the plastic and viscous properties of high-strength sheets.

Thus, the full use of the resource properties of instrumental high-strength sheet metal of the declared chemical composition is provided by the specified modes of its heat treatment.

An example implementation of the method.

Using the induction melting furnace IST 0.03 / 0.05 I1, steel of various chemical composition was smelted (Table 2).

The obtained ingots were heated in a PCM 3.6.2 / 12.5 chamber furnace to a temperature of 1200 ± 10 ° C. Next, the ingots were squeezed using a P6334 hydraulic press (simulation of the rough rolling stage) and on a single-strand reversible hot rolling mill 500 “DUO” (modeling the final rolling stage). The compression end temperature was 850–950 ° C. The ingots were rolled to a thickness of 6, 10, 20, 30, and 40 mm. The resulting sheets were cooled in air.

The heat treatment of rolled samples consisted of quenching at a temperature of 900-1200 ° C and subsequent tempering at a temperature of 400-900 ° C (Table 3), after which the resulting sheets were cut for tensile, hardness and impact bending tests.

Mechanical properties were determined on transverse samples in accordance with generally accepted conditions:

- tensile tests were carried out on flat samples according to GOST 1497;

- bending tests in accordance with GOST 9454 on samples with a V-shaped notch at a temperature of -40 ° C;

The test results showed that in the sheet steel obtained by the proposed method (options No. 2-4, table. 4), a combination of the highest strength, plastic and viscosity properties is achieved.

In cases of deviations from the declared parameters (options No. 1 and No. 5), as well as when using analogues and the prototype method, the required set of mechanical properties is not provided.

Thus, the use of the claimed method of production of high strength sheet steel tool achieves the desired result - obtaining high-strength steel with trudnosochetaemyh of properties: strength - yield strength σ 0.2 is not less than 900 N / mm 2, tensile strength σ in not less than 1050 H / mm 2 , hardness HBW not less than 340 units; plastic - elongation δ 5 not less than 12%; viscous - impact strength KCV -40 not less than 20 J / cm 2 .

Figure 00000001

Figure 00000002

Figure 00000003

Figure 00000004

Claims (4)

1. A method of manufacturing high-strength sheet metal from tool steel, including steelmaking, obtaining a continuously cast slab, its hot deformation, hardening and tempering of sheets, characterized in that the steel is melted of the following chemical composition, wt. %:
carbon 0.20-0.38 silicon 0.20-1.10 manganese 0.50-1.00 chromium 0.50-1.45 nickel 0.70-1.30 molybdenum 0.20-0.80 vanadium 0.02-0.16 aluminum 0.02-0.08 nitrogen 0.001-0.010 copper no more than 0.25 niobium 0.001-0.030 titanium 0.001-0.020 sulfur no more than 0,008 phosphorus no more than 0,013 iron rest,
wherein the hardening of sheets of the specified steel is carried out at a temperature of 930-980 ° C, tempering is carried out at a temperature of 575 ± 25 ° C.
2. The method according to p. 1, characterized in that the steel composition further comprises boron in the range of 0.001-0.005 wt. %
RU2016119835A 2016-05-23 2016-05-23 Method of manufacture of instrumental high-strength flats RU2631063C1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2680457C1 (en) * 2018-04-25 2019-02-21 Публичное акционерное общество "Трубная металлургическая компания" (ПАО "ТМК") High-strength oil country tubular good in cold-resistant performance (options)
RU2701325C1 (en) * 2018-09-17 2019-09-26 Публичное акционерное общество "Северсталь" (ПАО "Северсталь") High-strength steel and article made from it

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183573B1 (en) * 1997-02-25 2001-02-06 Sumitomo Metal Industries, Ltd. High-toughness, high-tensile-strength steel and method of manufacturing the same
RU2433191C1 (en) * 2010-10-25 2011-11-10 Открытое акционерное общество "Северсталь" (ОАО "Северсталь") Manufacturing method of high-strength plate steel
RU2442831C1 (en) * 2010-10-15 2012-02-20 Федеральное государственное образовательное учреждение высшего профессионального образования "Национальный исследовательский технологический университет "МИСиС" Method for production of high-strength steel
RU2460823C1 (en) * 2011-02-08 2012-09-10 Российская Федерация, от имени которой выступает Министерство промышленности и торговли (Минпромторг России) Dynamically resistant steel, and manufacturing method of plates from it
RU2474623C1 (en) * 2011-10-31 2013-02-10 Валентин Николаевич Никитин Method of producing high-strength martensitic sheet steel and thermal strain complex to this end

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183573B1 (en) * 1997-02-25 2001-02-06 Sumitomo Metal Industries, Ltd. High-toughness, high-tensile-strength steel and method of manufacturing the same
RU2442831C1 (en) * 2010-10-15 2012-02-20 Федеральное государственное образовательное учреждение высшего профессионального образования "Национальный исследовательский технологический университет "МИСиС" Method for production of high-strength steel
RU2433191C1 (en) * 2010-10-25 2011-11-10 Открытое акционерное общество "Северсталь" (ОАО "Северсталь") Manufacturing method of high-strength plate steel
RU2460823C1 (en) * 2011-02-08 2012-09-10 Российская Федерация, от имени которой выступает Министерство промышленности и торговли (Минпромторг России) Dynamically resistant steel, and manufacturing method of plates from it
RU2474623C1 (en) * 2011-10-31 2013-02-10 Валентин Николаевич Никитин Method of producing high-strength martensitic sheet steel and thermal strain complex to this end

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2680457C1 (en) * 2018-04-25 2019-02-21 Публичное акционерное общество "Трубная металлургическая компания" (ПАО "ТМК") High-strength oil country tubular good in cold-resistant performance (options)
RU2701325C1 (en) * 2018-09-17 2019-09-26 Публичное акционерное общество "Северсталь" (ПАО "Северсталь") High-strength steel and article made from it

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