Showing papers in "Metal Science and Heat Treatment in 1989"
36 citations
TL;DR: In this paper, an increase in carbon content from 0.8 to 1.2% in cast steels causes formation of chromium-containing boride and carboboride phases.
Abstract: 1.
An increase in carbon content from 0.8 to 1.2% in cast steels causes formation of chromium-containing boride and carboboride phases.
2.
With an increase in carbon content in steels the microhardness of structural components changes a little.
3.
The maximum hardness is exhibited by steel oil quenched from 1000–1000°C.
4.
Steels with 0.82–1.20% C has the greatest thermal stability (up to 900°C). In steels with 0.15–0.39% C with heating up to 900°C a marked reduction in hardness is observed.
21 citations
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7 citations
TL;DR: The depth of the hardened case changes proportionally to the parameter P/(dnP)0.4 as discussed by the authors, where P is the arc power, dn is the diameter of the plasmatron delivery nozzle, and v is the rate of movement.
Abstract: 1.
The plasma heating process of 9KhF steel provides obtaining of hardened surface cases with a martensitic structure. The depth of the hardened cases with a microhardness of more than 800 H may reach 1 mm.
2.
The depth of the hardened case changes proportionally to the parameter P/(dnP)0.4, where P is the arc power, dn is the diameter of the plasmatron delivery nozzle, and v is the rate of movement of the plasmatron.
3.
The thermal efficiency of the plasma-hardening process of 9KhF steel is 25–30% with the use of argon as the plasma-forming gas. With operation of the gun with a mixture of Ar+70% N2 the thermal efficiency decreases to 9–10%.
6 citations
TL;DR: In this article, the growth rate of diffusion layer during ionic vacuum nitriding of low-alloy steels is 2-5 times higher than that obtained with gas Nitriding.
Abstract: 1.
The growth rate of diffusion layer during ionic vacuum nitriding of low-alloy steels is 2–5 times higher than that obtained with gas nitriding. The advantage of these processes is retained for layers up to 0.3 mm thick, since the saturation rate decreases significantly with increasing holding time.
2.
The process of ionic nitriding, which ensures removal of the oxide film from the steel surface and activation of the surface and gas medium, is optimal for high-alloy steels; this increases the rate of saturation significantly.
3.
The difference in the nitriding methods under the conditions of the experiment in question does not exert a significant influence on the strength characteristics of the steels that we investigated. The prevailing effect of the reduction in the resistance to brittle failure as a result of an increase in the size of the diffusion zone and its hardness over the increase in the resistance to plastic deformation due to nitrogen saturation of the solid solution and the formation of a nitride phase is observed during static-bending tests.
6 citations
TL;DR: The defect "bright ring" originates at places where there are carbide bands in high speed steel near the welding seam as mentioned in this paper, and the defect is not due to incomplete fusion, as has been commonly assumed.
Abstract: 1.
The defect "bright ring" in fracture is not due to incomplete fusion, as has been commonly assumed.
2.
The defect "bright ring" originates at places where there are carbide bands in high speed steel near the welding seam.
3.
Carbide bands form in consequence of overheating of high speed steel in friction welding.
4.
To eliminate the defect "bright ring," the heating temperature has to be reduced in welding.
5 citations
TL;DR: The most likely mechanism of stress relief in ultrasonic treatment of parts of steel 40Kh13 is the shear mechanism whereas in thermal aging at 160-170°C it is the diffusional mechanism as mentioned in this paper.
Abstract: 1.
The application of heat treatment of products does not always cause effective reduction of residual elastic stresses whereas treatment with ultrasound at normal temperature ensures a sufficient degree of their relief.
2.
The most likely mechanism of stress relief in ultrasonic treatment of parts of steel 40Kh13 is the shear mechanism whereas in thermal aging at 160–170°C it is the diffusional mechanism.
3.
The optimal regime of ultrasonic treatment of parts is the action of ultrasound at normal temperature through oil for 5–60 sec.
5 citations
5 citations
TL;DR: In this article, the authors showed that the wear resistance of gray irons after surface fusion increases with an increase in the quantity of residual asustenite in the case hardened from the liquid state.
Abstract: 1.
The quantity of residual austenite in the case fused under the action of a heat source (laser or plasma) on the surface of steel or iron is unambiguously determined by the parameter P/d (dv)0.4, which is proportional to the maximum temperature at the end of action of the source.
2.
In 9Kh steel with an increase in the parameter P/d (dv)0.4 the quantity of residual austenite in laser fusion changes according to a curve with a maximum. In treatment with scanning of the laser beam the quantity of residual austenite in 9Kh steel continusouly increases with an increase in the parameter P/d (dv)0.4. The addition of scanning leads to an increase in the quantity of residual austenite in the case in comparison with treatment without scanning.
3.
With an increase in the parameter P/d (dv)0.4 the change in the quantity of residual austenite in the zone of surface fusion of gray irons is dependent upon the degree of solution of graphite in the molten material.
4.
The contact fatigue life of 9Kh steel after laser fusion of the surface is a maximum with 50–60% residual austenite in the laser hardened case. The wear resistance of gray iron after surface fusion increases with an increase in the quantity of residual asustenite in the case hardened from the liquid state.
TL;DR: In this paper, aqueous chloride solution with special additives preventing metal surface corrosion and reducing separation of components containing chlorine are used as quenching media for alloy steels, which is connected with an increase in hardenability and quenchability.
Abstract: 1.
Alloy and high-alloy structural steels during quenching may be subjected to forced cooling without the danger of forming quenching cracks, which is connected with formation of high compressive stresses at the surface of quenched articles.
2.
The mechanical properties (σ0.2 and σf) for alloy steels subjected to rapid cooling are 20–30% higher in individual cases than after oil quenching with a simultaneous increase in impact strength by a factor of two to three. This is connected with an increase in hardenability and quenchability of steel articles.
3.
It is suggested that aqueous chloride solutions with special additives preventing metal surface corrosion and reducing separation of components containing chlorine are used as quenching media realizing rapid quenching methods for alloy steels.
TL;DR: In this paper, the authors investigated the effect of holding time of specimens formed from medium-alloy tool steel 9KhS in liquid nitrogen; the amount of residual austenite in this steel after quenching from the optimal temperature of 850-870°C is negligible, and does not exceed 12%.
Abstract: In this connection, we investigated the effect of the holding time of specimens formed from medium-alloy tool steel 9KhS in liquid nitrogen; the amount of residual austenite in this steel after quenching from the optimal temperature of 850-870°C is negligible, and does not exceed 12%. The hardness, resilience, bending strength, and residual stresses were determined in accordance with Davidenkov's method during the gradual one-sided pickling of specimens in an electrolyte (45% H2SO 4 + 45% H3PO ~ + 10% H20) at 80°C.
TL;DR: In this article, a microstructure consisting of primary martensitic-austenitic cells, with surround a thin interlayer of residual austenite, is formed in the fusion zone as a result of liquation.
Abstract: 1.
During treatment with surface fusion of alloy steel 40Kh10S2M, a microstructure consisting of primary martensitic-austenitic cells, with surround a thin interlayer of residual austenite, is formed in the fusion zone as a result of liquation.
2.
On conversion from the laser treatment of steel, 40Kh10S2M without surface fusion to laser treatment with fusion, the structural characteristics and properties vary in a jumpwise manner.
TL;DR: In this paper, a reduction in the relaxation resistance of an electroslag weld with an austenitic structure with a small amount of ferrite is due to the greater deformation capacity of ferite and microvolumes of austenite adjacent to it.
Abstract: 1.
Presence in a welded joint of steel 08Kh18N10T of 2–2.5% δ-ferrite promotes an increase in the degree of first-order stress relaxation at 400–480°C without reducing strength properties and with retention of resistance to ICC.
2.
A reduction in the relaxation resistance of an electroslag weld with an austenitic structure with a small amount of ferrite is due to the greater deformation capacity of ferite and microvolumes of austenite adjacent to it.
TL;DR: In this article, the mechanical properties of steel Kh12MST as a function of tempering temperature have two maximum which indicates that these steels can be used in die stamping equipment with high speed automated punching machines where the working sections can obtain temperatures as high as 400°C.
Abstract: 1.
The presence of Ti (0.4–0.7%) and silicon (0.7–1.0%) in high-chromium die steels does not adversely affect the level of their manufacturing properties and leads to an increase in strength and wear resistance.
2.
The mechanical properties of steel Kh12MST as a function of tempering temperature has two maximum which indicates that these steels can be used in die stamping equipment with high speed automated punching machines where the working sections can obtain temperatures as high as 400°C.
3.
Steel Kh12MST is recommended for the manufacture of cold deformation dies which operate over a wide range of dynamic loading and also for the manufacture of the cutting parts of heavy-duty dies which operate under conditions of extreme wear.
4.
The application of steel Kh12MST (EP952) in punching dies will increase their durability during the production of magnetic current plates made of electrotechnical steel by not less than 1.7 times.
TL;DR: In tempering of hardened (purely austenitic) 110G13L steel carbide colonies consisting of plates of cementite-tye carbide with an increased manganese content between which is located α-phase depleted of manganous are formed as mentioned in this paper.
Abstract: 1.
In the structure of 110G13L steel hardened immediately after solidification there are carbides characterized by the presence of phosphorous and an increased manganese content up to 30%.
2.
In tempering of hardened (purely austenitic) 110G13L steel carbide colonies consisting of plates of cementite-tye carbide with an increased manganese content between which is located α-phase depleted of manganese are formed. In formation of these colonies diffusion of manganese by distances on the order of the interplate distances occurs.
3.
As-cast 110G13L steel contains carbides of two types: 1) carbides formed as the result of segregation in solidification with solution of them in heat treatment difficult because of the necessity of diffusion of manganese and phosphorous by signifcant distances; 2) carbides formed in cooling of the casting at temperatures below 900°C (primarily at temperatures of 600°C and lower), which are easily soluble in heat treatment.
TL;DR: Aluminum alloys are widely used as construction materials in industry; however, it's application is often limited by it's low melting point, insufficient mechanical strength and low corrosion resistivity in aggressive environments One way of increasing it's strength is through intermetallic phase hardening as discussed by the authors.
Abstract: Aluminum alloys are widely used as construction materials in industry; however, it's application is often limited by it's low melting point, insufficient mechanical strength and low corrosion resistivity in aggressive environments One way of increasing it's strength is through intermetallic phase hardening In this connection, aluminum-chromium-scandium alloys show considerable promise Scandium is a good innoculant considerably improving the morphology of the intermetallic phase being strengthened Alloying with chromium leads to higher corrosion resistivity against pitting [i]
TL;DR: In this article, it was shown that the thermal conductivity of acast iron can be increased by alloying it with copper, which can increase its wear resistance and machinability.
Abstract: 1.
Copper markedly increases the thermal conductivity of acast iron as a result of which there is an increase in its wear resistance and machinability.
2.
Under thermal cycling conditions copper separates in the form of a thin film at the cast iron surface and also preferentially at other interphase surfaces of the metal which gives it a positive role.
3.
To a greater extent than for nickel, copper reduces the tendency of cast iron towards cementite formation at the surface, which makes it possible to alloy it with increased amounts of carbide-forming elements (Cr, Mn, V).
4.
As a result of additional alloying with copper it is possible to exclude entirely scarce and expensive nickel from wear-resistant highly alloyed cast irons.
TL;DR: In this article, an analysis of thermodynamic calculations allows one to predict the changes in the sizes of the austenitic and ferritic grains after alloying with vanadium, and the effect of vanadium carbonitrides on the grain size can be determined by using the parameter Θ( √ √ n/d/n ) at the normalization temperature.
Abstract: 1.
During holding at temperatures of 950–1050°C vanadium carbonitrides, which are present in steel 16GFL in the cast condition, partially or completely dissolve and their size distribution changes.
2.
An analysis of thermodynamic calculations allows one to predict the changes in the sizes of the austenitic and ferritic grains after alloying with vanadium.
3.
The effect of the dispersed particles on the austenitic and ferritic grain sizes can be determined by using the parameter\([\mathop \sum \limits_i (f_i /d_i )]^{ - 1}\). This parameter represents the volume fraction (fi) and the size distribution of the particles (di) at the normalization temperature. The carbonitrides will have an effect on the grain size if\([\mathop \sum \limits_i (f_i /d_i )]^{ - 1}\)< 100 μm.
4.
Through the use of thermodynamic calculations, the proposed model allows one to predict the particle size distribution and the parameter\([\mathop \sum \limits_i (f_i /d_i )]^{ - 1}\) at the austenization temperature from data on the particle size distribution in the initial condition.
TL;DR: The medium UZSP-1 with polymer concentration of 3-4% and working temperature from 15 to 60°C can be used for quenching forgings and parts made of refined medium carbon low alloy steels type 40Kh as mentioned in this paper.
Abstract: 1
The cooling ability of aqueous 3–4% solutions of UZSP-1 in the temperature range 600–450°C is close to the cooling ability of low-temperature quenching oils and of 1% quenching medium PK-2
2
Raising the temperature of the solution reduces the hardening ability of the medium UZSP-1, and at 80°C the cooling rate in quenching becomes too low for obtaining completely martensitic structure in medium carbon low alloy steels
3
The medium UZSP-1 with polymer concentration of 3–4% and working temperature from 15 to 60°C can be used for quenching forgings and parts made of refined medium carbon low alloy steels type 40Kh instead of low-temperature quenching oils However, it is desirable that the working temperature and the concentration be chosen in dependence on the marque of the steel and the standard dimensions of the part concerned
4
When the medium UZSP-1 is used in industry, the quenching tanks have to be equipped with systems of cooling, mixing, temperature and level control In the process of operation of the quenching tank it is indispensable to check systematically the cooling ability, the temperature and other parameters of the medium UZSP-1 and to correct them
5
The use of the quenching medium UZSP-1 for the temper hardening of parts made of steels type 40Kh makes it possible to obtain the same complex of properties as when quenching oil is used
TL;DR: In this article, the effect of spheroidal graphite inclusions on the failure of ferritic cast iron depends on the condition of the matrix: in a ductile matrix, the graphite particles are centers of microcavity generation and they lead as a result of this to a reduction in the level of cast iron properties; in a brittle matrix, graphites have a favorable tendency of retarding brittle crack development and under certain conditions they lead to a change in failure mechanism.
Abstract: 1.
The effect of spheroidal graphite inclusions on the failure of ferritic cast iron depends on the condition of the matrix: in a ductile matrix spheroidal graphite particles are centers of microcavity generation and they lead as a result of this to a reduction in the level of cast iron properties; in a brittle matrix graphite particles have a favorable tendency of retarding brittle crack development and under certain conditions they lead to a change in failure mechanism.
2.
The effect of crack retardation at spheroidal graphite particles develops particularly clearly at low loading rates thus providing properties in cast iron comparable with steel.
TL;DR: In this paper, a change of the loading parameters (the load and the kind of motion) leads to a substantial change in the structural state of the surface layers of the material of friction pairs of parts.
Abstract: A change of the loading parameters (the load and the kind of motion) leads to a substantial change of the structural state of the surface layers of the material of friction pairs of parts. The regularities of this change can be expressed through the structural parameters of the material (β and α) which characterize its defectiveness and properties. The structural state of the material, in its turn, determines its tribotechnical characteristics, i.e., a certain level of weak resistance corresponds to a certain type of structure of the material. Thus the regularities of the behavior of the structure of material in a broad range of change of the external loading parameters are the basis for determining the limits of fitness for operation of a specified friction pair.