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.     

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     

Effect of low-rate isothermal plastic deformation on the structure and properties of ZhS6KP nickel alloy

ZhS6KP alloy is used in commercial production of blades of aircraft engines pressed in Widin presses. Standard heat treatment that consists in air hardening from 1220°C (4 h) and aging at 950°C for 2 h with cooling in air does not always provide an optimum combination of long-term strength and fatigue resistance for the alloy at 900°C. In this connection, the possibility of improving the fatigue resistance and the long-term strength while preserving the high level of short-term mechanical properties by conducting low-rate plastic deformation before the heat treatment is considered.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 31 – 33, July, 1996.     

Improvement of the technological plasticity of KhN56VMTYu-VD alloy

Conclusions The maximum technological plasticity of the KhN56VMTYu-VD alloy in the two-phase state is achieved after heat treatment by the following method: hardening at 1120°C (2 h) in air+aging at 975°C (2 h) with cooling in water.Kulebaksk S. M. Kirov Metallurgical Plant. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 40–42, March, 1981.     

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     

Structure and short-term creep resistance of alloy TsM2A after nitriding

Conclusions Internal intriding of the alloy TsM2A at 1500–1700°C causes particles of the strengthening phase ZrN, 0.0425–0.0640 m in size, to appear in the structure of the alloy. Such treatment makes it possible to increase short-term creep resistance at 1500°C by 2–2.5 orders of magnitude, and to increase the microhardness of the alloy to H 280–340.Moscow Institute of Steel and Alloys. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 29–31, February, 1983.     

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.     

Heat resistance and structure of alloy PlRd7 in relation to preliminary deformation

Conclusions The degree of preliminary deformation affects the structure and the creep rate of alloy PlRd7 after annealing: at 1400°C the creep resistance of the alloy is lowest after 15% deformation and at 1200°C after 8% deformation.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 53–55, November, 1970.     

Heat treatment of large forgings of titanium alloy VT3-1

Conclusion The optimal heat treatment for large forgings of alloy VT3-1 consists of heating at 870° for 2 h, air cooling, heating at 650° for 2 h, and air cooling.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 65–66, June, 1977.     

Influence of Silicon and Aluminum Additions on the Oxidation Resistance of a Lean-Chromium Stainless Steel

The effect of Si and Al additions on the oxidation of austenitic stainless steels with a baseline composition of Fe–16Cr–16Ni–2Mn–1Mo (wt.%) has been studied. The combined Si and Al content of the alloys did not exceed 5 wt.%. Cyclic-oxidation tests were carried out in air at 700 and 800°C for a duration of 1000 hr. For comparison, conventional 18Cr–8Ni type-304 stainless steel specimens were also tested. The results showed that at 700°C, alloys containing Al and Si, and alloys with only Si additions showed weight gains about one half that of the conventional type-304 alloy. At 800°C, alloys that contained both Al and Si additions showed weight gains approximately two times greater than the type-304 alloy. However, alloys containing only Si additions showed weight gains four times less than the 304 stainless. Further, alloys with only Si additions preoxidized at 800°C, showed zero weight gain in subsequent testing for 1000 hr at 700°C. Clearly, the oxide-scale formation and rate-controlling mechanisms in the alloys with combined Si and Al additions at 800°C were different than the alloys with Si only. ESCA, SEM, and a bromide-etching technique were used to analyze the chemistry of the oxide films and the oxide–base-metal interface, in order to study the different oxide film-formation mechanisms in these alloys.     

High-Temperature Oxidation Behavior of the Co-Base Superalloy DZ40M in Air

The oxidation behavior of the Co-base superalloy DZ40M was studied in air at900–1100°C for times of up to 2000 hr. The results indicated thatthis alloy can grow a protective oxide scale at 900 and 1000°C duringisothermal oxidation, but not at 1100°C because of serious cracking andspalling of the oxide scales. Moreover, an internal-precipitate zone formedin the subsurface region of the alloy at all temperatures and times. Theprecipitates were rich in Cr in the vicinity of the alloy–scaleinterface and rich in Al deep in the alloy. The internal-precipitatemorphology changed from a granular to needlelike shape with increasingoxidation temperature.     

Mechanical properties of alloy KhN35VTYu at low temperatures

Conclusion Alloy KhN35VTYu has high values of _u, _0.2, and a_0.25 at normal and cryogenic temperatures after hardening at 1050°C for 3 h in air and aging at 700°C for 3–8 h. The alloy is not sensitive to stress concentration. Increasing the hardening temperature to 1200°C leads to a significant decrease in the values of _0.2 and a_0.25.VNIIÉM, IMASh. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 28–29, May, 1991.     

Cyclic-Oxidation Resistance of Protective Silicide Layers on Titanium

Titanium was powder siliconized and gas nitrided, in order to improve its cyclic-oxidation resistance. Siliconizing was performed in a pure-silicon powder at temperatures in the range of 800–1100° C for 3–48 h. Gas nitriding was carried out in pure N₂ at 1100° C/12 h. Cyclic-oxidation experiments with the siliconized and nitrided samples were conducted in air at 850 and 950° C for up to 560 h. It was found that the siliconized layers grew according to the parabolic law with the activation energy for siliconizing E_S being 47.2 kJ mol^–1. Powder siliconizing at 900–1100° C/3 h produced multi-phase layers, in which Ti₅Si₃ silicide predominated The siliconizing temperature of 800° C/3 h appeared to be insufficient, because it led to a non-uniform surface layer with a slight protective effect. The nitrided layers were composed of titanium nitride TiN and -Ti(N) intestitial solid solution. Measurement of the oxidation kinetics revealed that the titanium siliconized at 900–1100° C/3 h oxidized much more slowly than pure Ti, Ti–6Al–4V alloy and nitrided titanium. Microstructural investigation revealed the complex sub-structure of the scales on the siliconized samples which was composed of rutile+silica, rutile and nitrogen-rich sub-layers. The mechanism of high-temperature cyclic oxidation of the siliconized and nitrided titanium is discussed.     

Strengthening heat treatment of alloy VT16 in vacuum

Conclusions Alloy VT16 can be strengthened by heat treatment in vacuum under the following conditions: heating at 775–800° for 2 h, cooling in the container in water, and aging at 500° for 8 h.The alloy subjected to this treatment has the following properties; _b = 103–107 kgf/mm², =59–63%, ₅ = 15.1–16.1%.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 65–67, May, 1978.     

Effect of chromium on the oxidation resistance of TiAl intermetallics

The effect of 10 at.%Cr on the oxidation resistance of TiAl intermetallic compound at 800–1100°C in air was investigated. The results indicated that 10 at.%Cr equally substituting for Ti and Al in TiAl alloy had duplex effects on the isothermal kinetics of DAL At lower temperatures (800–900°C), Cr increased the oxidation rates as a result of the doping effect of Cr in the scale and at higher temperatures (1000–1100°C), especially at 1100°C, Cr significantly reduced the oxidation rates as a result of the formation of a continuous Al₂O₃ film on the surface. 10 at.%Cr only substituting for Ti in TiAl alloy remarkably reduced the oxidation rates at all temperatures by about two orders of magnitude. Moreover, 10 at%Cr significantly improved the cyclic-oxidation rsistance of TiAl alloy.     

The sulfidation of pure Co, Y, and of a Co-15 wt.% Y alloy in H2-H2S mixtures at 600–800°C

The corrosion of pure Co and Y and of a Co-15 wt.% Y alloy in H₂-H₂S mixtures providing a sulfur pressure of 10^–8 atm. at 600–800°C and also of 10^–7 atm. at 800°C was was studied to examine the effect of yttrium on the sulfidation resistance of pure cobalt. The alloy was nearly single phase, containing mostly the intermetallic compound Co₁₇Y₂ plus a small amount of cobalt solid-solution. For all conditions except for 800°C under 10^–8 atm. S₂, the alloy formed multilayered scales consisting of an outer region of pure cobalt sulfide, an intermediate region of a mixture of cobalt sulfide with yttrium oxysulfide and finally an innermost layer of a mixture of yttrium oxysu fide with cobalt metal. At 800°C under 10^–8 atm. S₂, below the dissociation pressure of cobalt sulfide, the alloy formed only a single layer composed of a mixture of metallic cobalt with yttrium oxysulfide. Pure yttrium produced only the oxysulfide Y₂O₂S, as a result of the large stability of this compound and of the presence of some impurities in the gas mixtures used. The corrosion kinetics were generally rather complex, but except at 800°C under 10^–8 atm. S₂, the addition of yttrium reduced the sulfidation rate of cobalt, even though the formation of a continuous protective external layer of a pure yttrium compound was never achieved. Finally, when the gas-phase sulfur pressure was above the dissociation of cobalt sulfide the corrosion rate of yttrium was significantly lower than that of Co-15 Y. The internal sulfidation of Y in Co-15 Y was not associated with depletion of Y in the alloy. This difusionless kind of internal attack is typical of binary A-B alloys presenting a very small solubility of the most-reactive component B in the base metal A, which restricts severely the flux of B from the alloy toward the alloy-scale interface.     

Recrystallization of low-alloy Cu−Cr−Zr alloys

Conclusions To obtain the given combination of properties it is recommended that the Cu–Cr–Zr alloy be heat treated as follows: quenched from 880°, cold rolled with 90% deformation, aged at 600° for 2 h, cold worked with over 50% deformation, and annealed at 450° for 2 h.State Scientific-Research and Design Institute of Alloys and Treatment of Nonferrous Metals. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 9, pp. 53–54, September, 1979.     

Strengthening of silicon Monel

Conclusions In silicon Monel (S-Monel) the (Ni, Fe)₃Si strengthening phase is formed. This phase is precipitated at a high rate from the solid solution during cooling in air from 1000–700°C and the alloy is considerably strengthened as the result. The alloy is additionally strengthened during aging at 600–650°C.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 48–49, June, 1966A. I. Kapotova took part in the experiments.