The stability of austenite in alloyed cast iron at low temperatures

Conclusions To prevent structural (and volume) changes in parts of austenitic cast irons at temperatures down to –70° the cast iron should contain at least 15% Ni and 1.5–2.0% Mn. The cast iron must also be cooled intensely from 700–750° during the heat treatment.Gor'kii Automobile Plant. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 49–50, December, 1970.     

Heat Treatment of Cast Carburizing High-Speed Steel Alloyed with Ti, Nb, and V

Special features of the structure and phase composition of cast carburizing high-speed steel of the ferrite-carbide class and the laws of their variation in the process of the carburizing hold and subsequent heat treatment are described. The temperature of heating for quenching was varied within 1180 – 1220°C, and the tempering temperature was varied within 560 – 640°C using the hardness and heat resistance as criteria. The results of mechanical tests of heat treated steels are analyzed.     

Effect of alloying elements on the structure of cast hypereutectoid steels after heat treatment

Conclusions In selecting a treatment schedule providing uniform distribution of carbides in cast hypoeutectic steels for rolls it is necessary to take account of the fact that the cementite network along grain boundaries dissolves in the temperature range 850–950°C. In steel with a low content of carbide-forming elements eutectic cementite does not dissolve at these temperatures. As the heating temperature is increased from 850 to 1100°C intense surface graphitizing commences, which points to the possibility of forming graphite inclusions with bulk heat treatment. With an increase in the content of chromium and molybdenum in steel the graphitizing process is suppressed, and carbon is bonded into stable carbides. In such a steel eutectic carbides dissolve at 1050–1100°C. Preparation of a structure with uniform carbide distribution during heat treatment is only possible in steels containing about 2% Cr and not less than 0.3% Mo.Ukrainian Research Institute of Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 62–64, August, 1987.     

Effect of heat treatment on the properties of deformed alloy 36N

Iron-nickel alloy 36N (Invar) is widely used in industry as a material having an anomalously low and almost constant thermal coefficient of linear expansion (TCLE) in the temperature range of 20 – 100°C. This value of the coefficient is attained after heat treatment of the deformed semifinished product by the regime of quenching from 830°C in water, tempering at 315°C for I h, and aging at 95°C for 48 h. The minimum value of the TCLE is provided by the quenching operation, whereas the tempering and aging prevent growth of the TCLE during long-term operation of Invar. The use of such heat treatment for rods and wire of alloy 36N guarantees a TCLE of at most 1.5 × 10^–6 °C^–1. It is known that the value of the TCLE and the level of the mechanical properties of Invar can be changed by changing the temperature and deformation regime of its treatment. The aim of the present work is to determine an optimum regime of heat treatment of the alloy after drawing that would ensure, without a finishing treatment, a TCLE not exceeding 1.0 × 10^–6 °C^–1 in the temperature range 20 – 100°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 31 – 32, April, 1996.     

Low-temperature cyaniding of cylinder block sleeves

Conclusions We recommend the following heat treatment for the cylinder sleeves of certain tractor and automobile engines; it ensures a high wear resistance and does not induce warping: a) annealing for stress relief, with heating at 75–100 deg/h to 580–600°C, soaking, cooling at the rate of 40–50 deg/h to 200°C; final machining, including honing; b) gas cyaniding 6 h at 560–580°C in a medium of 70% carburizing gas and 30% ammonia.Bauman MVTU, Moscow Automobile Plant. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 60–62, July, 1967.     

A study on the oxidation characteristics of cast irons containing aluminum

Isothermal-oxidation characteristics of cast irons containing aluminum (5–15% Al) from 700 to 1000°C in air have been studied. In addition to massgain measurements, the morphology and composition of the oxide scales have been examined by SEM-EDX system and XRD analysis. A normal Fe–5Al–C alloy does not develop protective, adherent scales. Even the addition of misch metal and calcium silicide to such an alloy does not improve its oxidation resistance. But aluminum cast iron develops considerable oxidation resistance only when a sufficient quantity of silicon is also present in the alloy. Treatment of the alloy with misch, metal and calcium silicide together assists in protective scale formation. Among the alloys investigated Fe–15Al–Si–C treated with misch metal and calcium silicide shows minimum oxidation at 1000°C.     

Heat treatment of two-layer plates of St. 3 steel cladded with high-chromium stainless steels 0Kh17T and Kh25T

Conclusion The optimal heat treatment for bimetals, guaranteeing the mechanical properties specified in GOST 10885-64 and the possibility of shearing and cold straightening, was a multistage treatment consisting of heating to 830–850°C, soaking 20–30 min, slow cooling to a temperature below Ac₁, and quenching in water. This treatment can be replaced by a double heat treatment consisting of normalization at 830–850°C followed by quenching in water from 650–700°C.TsNIIChERMET, Chelyabinsk Metallurgical Plant. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 68–70, April, 1968.     

Recommended heat treatment for case hardened parts made of 18KhNVA steel

Conclusions The optimum heat treatment conditions for case hardened 18KhNVA steel resulting in a stable hardness HRC>60 are quenching from 780–800°C in oil or air and subsequent treatment at –70°C for 20–30 min followed by tempering for 2 h at 150–160°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, p. 47, June, 1964     

Heat treatment of cast aluminum alloys obtained by application of regulated pressure during crystallization

conclusion For castings of AK8 alloy obtained by application of regulated pressure during crystallization, we recommend the following heat treatment conditions: homogenization at 460–470°C for 8 h, quenching from 505–510°C, aging at 150–170°C for 3.5–4h. After treatment according to this procedure, a hardness of 72–74 HRB is achieved for the alloy.Vladimir Polytechnical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 36–39, October 1992.     

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.     

Recrystallization of iron-aluminum alloys

Conclusions In Fe–Al alloys containing up to 16% Al the grains increase in size at 1100–1200°C. The increase in grain size is one of the reasons for the poor deformability of these alloys at low temperatures, and therefore the intermediate heat treatment must be carried out at temperatures no higher than 900°C.Central Scientific Research Institute of Ferrous Metallurgy Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 36–38, June, 1966     

Effect of alloying elements on austenite transformation kinetics in chromium-nickel rolling mill cast irons

Conclusion Tungsten both with small and large amounts of supercooling increases austenite stability, but niobium with small amounts of supercooling (550–450°C) decreases it, and with large amounts (350°C and below) it increases its stability. On alloying chromium-nickel cast iron with cobalt austenite isothermal decomposition moves to the left, and alloying with boron accelerates the austenite decomposition process in the temperature range 550–500°C with an increase in its stability in the range 500–200°C.Dnepropetrovsk Metallurgical Institute. Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 58–60, July, 1984.     

Mechanical and magnetic properties of cast irons VCh 50-2 and KCh 50-5 after temper hardening

Conclusion After heat treatment cast iron changes both its mechanical and magnetic properties, which is connected with structural transformations in the matrix. Thus, from results of the change in magnetic properties for cast iron, it is possible to estimate the amount of heat treatment, i.e., to establish the structural and phase condition of the cast iron, and to estimate the completeness of transformations occurring during quenching and tempering.As parameters for monitoring the heat treatment of HCSG and PMC in the tempering range 600–750°C, it is possible to use and µ₃₀₀, and µ₃₀₀ is to be preferred. In the range t_tem=500–600°C should be used.Results of these studies have been used in developing an electromagnetic structurescope by means of which measurements have been made of differential dynamic magnetic permeability for monitored and reference articles located in continuous eddy-current converters.Test for a structurescope under production conditions at the Volga Automobile Factory during quality control of temper hardening for PMC and HCSG castings demonstrated its high efficiency, reliability and productivity.Zaporozhe Automobile Factory "Kommunar." Zaporozhe Machine Building Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 10–11, June, 1987.     

Increasing the relaxation resistance of heat resistant Ni−Cr alloys by conditioning

Conclusions The effect of repeated loading (conditioning) in the first period of relaxation on the relaxation resistance of heat resistant Ni–Cr alloys depends on the working temperature. At 750–800°C the effectiveness of this treatment is adequate for practical use (although it is smaller than at 700–725°C). At temperatures up to 850°C conditioning cannot prevent the intensive relaxation weakiening that is characteristic of Ni–Cr alloys at this temperature.Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 53–57, October, 1972.     

The oxidation resistance of a sputtered,microcrystalline TiAl-intermetallic-compound film

The oxidation behavior of a cast TiAl intermetallic compound and its sputtered microcrystalline film was investigated at 700–900°C in static air. At 700°C, both the cast alloy and its sputtered microcrystalline film exhibited excellent oxidation resistance. No scale spallation was observed. However, at 800–900°C, the oxidation kinetics for the cast TiAl alloy followed approximately a linear rate law, which indicates that it has poor oxidation resistance over this temperature range. The poor oxidation resistance of TiAl was due to the formation of an Al₂O₃+TiO₂ scale which spalled extensively during cooling. Nevertheless, the sputtered, TiAl-microcrystalline film exhibited very good oxidation resistance. The oxidation kinetics followed approximately the parabolic rate law at all temperatures. Although the composition of the scales was the same as that of scales formed on the cast alloy, the scales formed on the sputtered microcrystalline-TiAl film are adherent strongly to the substrate. No scale spallation was found at 700–850°C, while a small amount of spallation was observed only at 900°C. This indicates that microcrystallization can improve the oxidation resistance of the TiAl alloy.     

The hardness and corrosion resistance of nickel alloys with molybdenum and tungsten

Conclusions The newly-developed Ni–Mo–W corrosion resistant hard alloys (N65M20V15 and N55M20V25) have a corrosion rate of no more than 0.2 mm/year in 30% HCl at 60°C and in 70% H₂SO₄ at 90°C, with a hardness as high as HRC 52.The alloys are precipitation-hardening. To obtain a high hardness it is recommended that they be heat treated by water quenching from 1000–1050°C and aging at 800°C for 4 h.Deceased.Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 24–27, March, 1972.     

Extreme diffusional activity in steel in a state of transformation

Conclusions The pretransformation state in steel is characterized by an increased diffusional activity of the iron atoms. The temperature range of this state may be utilized for plastic deformation and heat treatment in steels. The diffusional mobility of the atoms and the plasticity of the steel in the pretransformation state (at 700–720 and 780–800°C for carbon and high speed steel, respectively) are approximately the same as those at 1100–1200°C.Utilization of the pretransformation state for technological purposes permits economies in the use of energy, due to the decreased process temperatures.The narrower temperature interval for commercial processing (±3–5°C) should not be an obstacle to its use in practice, since presently existing equipment permits temperature regulation with an accuracy up to ±1°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 13–15, July, 1990.     

Effect of heat treatment on the relaxation resistance of the KhN77TYu alloy

Conclusions Double heat treatment consisting of quenching from 1050–1080°C in air and tempering for 16 h in air at 750°C provides the highest resistance to relaxation in the KhN77TYu alloy.Central Scientific Research Institute of Ferrous Metallurgy Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 1, pp. 60–63, January, 1966