Effect of HTMT on the thermal fatigue resistance of die steels

Conclusions HTMT increases the thermal fatigue resistance of steel 4Kh4MVFS with cyclic heating to 650°. The rate of crack growth slows down and the number of cycles to appearance of the first crack remains unchanged. The thermal fatigue resistance of steels 5KhNV and 4Kh5MFS does not change with thermal cycling to 500 and 550° after HTMT, but decreases with thermal cycling at higher temperatures.Chelyabinsk Polytechnic Institute. Chelyabinsk Metallurgical Factory. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 29–31, March, 1979.     

Effectiveness of thermal shotblasting for casehardened steels

The shotpeening process that is used in industry has an ambiguous influence on the contact surface fatigue life of the casehardened steels: it improves this characteristic of the steels 12Kh2N4A and 12Kh2NVFA when using the rational hardening regime and reduces the contact surface fatigue life for any regimes of shotpeening of the temperature-resistant steel 16Kh3NVFMB-Sh. Low-temperature post-deformation annealing improves the contact surface fatigue life of both steels, but it limits their operating temperature. We can broaden the operating temperature range by the use of thermal shotblasting, which involves strain hardening of the casehardened surface that is heated to 250 °C. This is shown in the present work.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 21–24, May, 1994.     

Structure and properties of 4Kh3VMFS and 3Kh3VMF heat-resistant die steels

Conclusion The austenitic grain growth of types 4Kh4VMFS and 3Kh3VMF hot work die steels in heating may be caused by solution of carbides, migration of boundaries, or "scattering" of them, which determines the optimum hardening temperature of these steels, 1120–1140°C for 4Kh3VMFS and 1060–1080°C for 3Kh3VMF, respectively. The combination of properties of the new steels significantly exceeds that of the standard.The Ukrainian Scientific-Research Institute for Special Steel. Translated from Metallovdenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 38–41, November, 1985.     

Operational stability of stamping tools of steel 50Kh2GSMF

In preceding work the authors developed and tested under industrial conditions hot-deformation die tools of the new steel 50Kh2GSMF and compared them with tools of steels 50KhGSMF and 50KhNM. A comparative analysis has shown that the operational stability of steels of the Cr−Mn−Mo−V−Si system is considerably higher than that of the Cr−Ni−Mo system. Steel 50Kh2GSMF possessed the highest stability. In the present work the operational stability of die inserts of the indicated steels and steels 50KhNV and 55NiCrMoV7 (50KhNMF) is compared. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 37–38, January, 1997.     

Structural heredity in low-carbon martensitic steels

The reason for the development of low-carbon martensitic steels (LCMS) is the absence of universal and comparatively inexpensive structural iron alloys combining high mechanical properties with processibility. Hardening of LCMS commonly includes heating above Ac ₃ (930 – 950°C) and air-cooling. The present paper studies the possibility of heat hardening after heating in the intercritical temperature range, the role of special carbides in realization of structural heredity, the laws of formation of structure, and the properties of commercial LCMS of grades 10Kh3GNM and 12Kh2G2NMFT.     

Effect of heat treatment on corrosion cracking of high-strength steels

Conclusion The susceptibility of steel to corrosion cracking depends to a large extent on the tempering temperature. With increasing tempering temperatures the susceptibility of oil-quenched steels decreases. At the tempering temperature at which preferential martensite decomposition occurs in former austenite grain boundaries one observes an increase of the susceptibility to corrosion cracking. For steels 30Kh-GSA, 30KhGSNA, and 25Kh2GNTA this increased susceptibility occurs on tempering at 250°C, for steel ÉI643 at 400°C, and for steel D at 450–500°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 45–48, February, 1968.     

Recrystallization of cold-drawn stainless steel

Summary Lengthening the holding time during the heating of cold-drawn 1Kh18N9T steel tubes reduces the initial and final recrystallization temperatures.An intensive lowering of the recrystallization temperature range occurs within the initial 10 min.The recrystallization process develops during the treatment of cold-drawn tubes at 975 to 1050°C as a result of heating without holding, and at 750 to 850°C by heating and a 3 hr holding period.     

A direct electron-microscopic investigation of the processes of austenitizing of 60F1 steel

Conclusions The formation of austenitic grains in 60F1 steel consists of two stages, recreation of the grains after the previous heating (coarse with overheating) and their refinement as a result of recrystallization. Recrystallization of the austenite of 60F1 steel occurs at temperatures of Ac₃+(70–90)°C, i.e., at 870–890°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 13–14, January, 1981.     

Structure and Properties of Low-Alloy High-Nitrogen Martensitic Steels

Special features of structure formation and mechanical properties of low-alloy martensitic steels with superequilibrium content of nitrogen and low content of carbon are considered. Experimental data on the effect of the temperature of heating for hardening and tempering on the structure, strength, and ductility of these steels are presented. The advantages and disadvantages of the introduction of nitrogen into low-alloy martensitic steels instead of carbon are discussed. It is shown that steel 10Kh3A combines high strength with high ductility. This steel is considered as a material for heavily loaded parts and nonwelded structures instead of high-strength steels alloyed with Ni, Mo, V and other expensive and scarce elements.     

Structural materials for atomic reactors with liquid metal heat-transfer agents in the form of lead or lead—Bismuth alloy

Natural safety nuclear reactors operate at a working temperature of the liquid-metal lead heat-transfer agent equal to 550°C, which intensifies the metal corrosion and is fraught with the danger of thermal embrittlement. It is shown that long-term operation of the equipment requires inhibition of the heat-transfer agent by oxygen and the use of silicon steels. However, alloying with silicon increases the susceptibility of the steel to thermal and radiative embrittlement. This makes it necessary to create new steels with a stable structure. The suggested composition of austenitic steel 04Kh15N11S3MT is designed for shell and internal structures, and steel 10Kh9NSMF is designed for the pipe system of the steam generator. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 20–24, September, 1999.     

Die steels for high-speed automatic hot die forging machines

Conclusions Steel 3Kh3M3F produced by ESR has the best combination of strength, hardness, and toughness, and also resistance to crazing. The life of punches made of this steel was double that of standard steel 3Kh2V8F and considerably higher than that of steels with a higher carbon content (0.4–0.5%).The life of 3Kh3M3F punches (ESR) was three to four thousand bearing races higher than that of the same steel melted in an open furnace.These data lead us to recommend that punches for high-speed water-cooled presses be manufactured from steel 3Kh3M3F (ESR) with the following chemical composition: 0.26–0.34% C, 2.8–3.3% Cr, 2.5–2.9% Mo, 0.40–0.60% V (ChMTU-1-963-70).The following heat treatment is recommended: preliminary heating in an electric furnace at 500–510°, salt bath at 850–860°, and salt bath at 1040±10°. The parts should be quenched in oil with a temperature of 120–150°. The first tempering after quenching should be conducted in a salt bath at 600° for 2 h, with cooling in air. The second tempering should be conducted in a salt bath at 560° for 2 h, with cooling in air. The hardness of the parts after heat treatment is HRC 49–51.All-Union Scientific-Research Institute of the Bearing Industry. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 20–25, November, 1973.     

High-temperature nitriding of chromium and chromium-nickel steels

Conclusions High-temperature nitriding accelerates the diffusion of nitrogen in steel. Nitriding at 700° for 3 h resulted in a case depth of 0.20–0.27 mm with HV 750–1000 for ferritic steels 0Kh13 and Kh16, and a case depth of 0.09 mm with HV 950 for austenitic steel Kh18N9T.Moscow Highway Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 19–22, February, 1971.     

Study of the possibility of liquid boriding of high-speed steels

Conclusions A beneficial effect of boriding may be expected only on a tool which is made of steel having a hardening temperature not above 1080°C and the technical specifications of which do not have a ground shape, e.g., dies made of steel 9KhS, taps and reamers made of steel U12, and also forged tools made of steel Kh12.For high-speed steels it is apparently only possible to subject those tool to boriding for which red hardness is not obligatory (e.g., certain components of special bearings) of fusion of the cutting edge is acceptable (e.g., certain types of cutters). For the rest of the objects made of high-speed steels boriding is unsuitable.All-Union Scientific-Research Tool Institute (VNII). Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 30–32, November, 1982.     

Special Features of Formation of Structure and Properties of Low-Carbon Martensitic Steel 12Kh2G2NMFT

The structure and mechanical properties of steel 12Kh2G2NMFT after continuous cooling at a rate of 600 – 0.035 K/sec and after cooling with isothermal holds in a temperature range of 300 – 650°C are investigated. It is shown that a lath martensite structure with a high level of strength and ductility is formed in a wide range of cooling conditions. The decrease in the impact toughness observed under isothermal conditions in a narrow temperature range below M _i (360 – 410°C) is shown to be connected with the processes of tempering of freshly formed isothermal martensite.     

Nitriding of die steels 4Kh5MFS and 5Kh2MNF in a vibrofluidized bed

Conclusions Nitriding of steels 4Kh5MFS and 5Kh2MNF in a vibrofluidized bed (graphite with a particle size of 0.2–0.4 mm) should be conducted at 540–570° with the ammonia entering below the bed at a rate of 1.1 liter/min, frequency of vibration 22 Hz, amplitude of vibration 2.0 mm, and acceleration of vibration 4g. After 5 h the case depth is 0.25 mm for steel 4Kh5MFS and 0.22 mm for steel 5Kh2MNF.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 57–58, November, 1978.     

Effect of frictional heating on the surface-layer structure and tribological properties of titanium nickelide

The effect of frictional heating (whose intensity was varied at the expense of changes in the sliding velocity from 0.35 to 9.00 m/s) on the rate of wear, friction coefficient, friction thermopower, structure, and microhardness of the Ti_49.4Ni_50.6 alloy in a microcrystalline (MC) state with grains 20–30 μm in size and in a submicrocrystalline (SMC) state with grains 300 nm in size has been investigated. The tribological tests were conducted under the conditions of dry sliding friction in air using the finger-disk (made of steel Kh12M, hardness HRC = 63) scheme at a normal load of 98 N. Due to the frictional heating, the temperature in the surface layer 0.5 mm thick of the samples changed from 150–200 (at a sliding velocity of 0.35 m/s) to 1100°C (at a velocity of 9 m/s). The alloy structure has been studied with the help of metallographic and electronmicroscopic (scanning and transmission microscopy) methods. It has been shown that the rate of wear of the titanium nickelide in the MC and SMC structural states is more than an order of magnitude lower than in the 12Kh18N9 steel and several times less than in the 40Kh13 steel. The fracture of the friction surface of the titanium nickelide occurs predominantly by the fatigue or oxidation-fatigue mechanisms, which are characterized by a relatively low wear rate, whereas the 40Kh13 and 12Kh18N9 steels show a tendency to intense thermal adhesive wear (seizure) at velocities higher than 0.35 m/s. It has been shown by the electron-microscopic investigation that nanocrystalline structures consisting of crystals of the B2 phase, oxides of the TiO₂ type, and some amount of martensite B19′ are formed in the process of friction in the surface layer of the titanium nickelide. It has been concluded that an enhanced wear resistance of the titanium nickelide is caused by the high heat resistance (strength) and high fracture toughness of the nanocrystalline B2 phase and by the presence of high-strength thermostable oxides of the TiO₂ type formed upon friction.     

Impact toughness and plastic properties of composite layered samples as compared to monolithic ones

Effects of testing conditions on the mechanical properties and fracture of a material in the course of impact loading have been studied. Using steels of various phase compositions (ferritic steel 08Kh18T1 and austenitic steel 10Kh18AG19) tested in a wide temperature range (from 20 to ?196°C), the advantage of layered structures has been established as compared to monolithic. It has been shown that the testing of composite samples simulates the loading-affected behavior of the ferritic steel 08Kh18T1 with an inhomogeneous layered microstructure obtained during repeated hot rolling with a reduction of no less than 65%.