Metal Science and Heat Treatment

Zakharova, V.; Smirnov, N.

doi: 10.1007/BF00647805pmid: N/A

1. The degree of decarburizing was highest in a weakly oxidizing atmosphere of commercial nitrogen and lowest in the dry nitrogen-hydrogen mixture (0.06% H2O). In a reducing atmosphere the carbon is removed from the steel mainly as the result of interacting with the water vapor to form CO. 2. Decarburizing-annealing in a weakly oxidizing or reducing atmosphere is recommended as a method of preparing the surface of carbon steel for enameling.

Vilenskaya, T.; Lifshits, A.; Mikhailov, L.

doi: 10.1007/BF00647806pmid: N/A

Murav'ev, V.

doi: 10.1007/BF00647807pmid: N/A

1. Water glass with additions of talc, kaolin, granulated fireclay, aluminum oxide, chromium oxide, and titanium oxide is not an effective coating, particularly for preventing decarburizing of steels. 2. Ground glass is a better base for protective coatings. For preventing decarburizing of steels and for practical use the best coating was that consisting of 40% fireclay, 50% ground glass, and 10% talc. 3. The nitrogen in the air is a good protective medium for preventing decarburizing when the furnace is sealed and the ratio of metal to the air is suitable. 4. The atmosphere resulting from the interaction of charcoal and air in the apparatus with a sand seal prevents oxidizing of copper and copper alloys.

Belyaev, A.; Borisov, A.; Butovskii, N.; Vorob'ev, F.; Kogan, G.

doi: 10.1007/BF00647808pmid: N/A

Ryabchenkov, A.; Maksimov, A.

doi: 10.1007/BF00647809pmid: N/A

1. The fatigue limit and long-term strength of structural materials (steel 45, KhN70VMYuT, KhN35-VT, 1Kh12V2MF, and \'EP126) were investigated in oxidizing media (air, fuel combustion products) and inert media (purified and unpurified argon). It was found that in oxidizing media, in which an oxide film is formed, the heat-resisting properties are higher than in inert (nonoxidizing) media, in which no oxide film is formed. The difference in the levels of the long-term strength and fatigue limit increases with the temperature and testing time. 2. We determined the basic physicochemical processes affecting the weakening of the surface layer in monoxidizing media and the strengthening of the surface layer in oxidizing media. 3. We determined the principal means of increasing the heat resistance of structural materials and proposed new principles of alloying steels and alloys intended for operation at high temperatures in nonoxidizing gaseous media.

Parshin, A.; Kolosov, I.

doi: 10.1007/BF00647810pmid: N/A

The decrease in the length of samples during creep tests at 500–650°C does not mean that no positive creep occurs. It does, but the reduction in the specific volume of the material resulting from redistribution of titanium and nickel preceding the precipitation of secondary phases of the Ni3Ti type is superposed on the effect of creep. In this case an increase of stress must reduce the intensity of negative creep processes.

Gofman, Yu.; Pogrebinskii, F.

doi: 10.1007/BF00647811pmid: N/A

1. During operation of 12Kh1MF pipes with a nonrecommended structure at 570°C there are substantial changes in the structure, leading to a considerable drop of the long-term strength. 2. In pipes with an alliptic cross-section the small axis increases and the large axis decreases during use. The residual deformation should be calculated from the changes in the perimeter.

Kosma, Dante; Konstantinescu, Aurel

doi: 10.1007/BF00647812pmid: N/A

1. The steel of the following chemical composition has the best combination of properties: 0.16%C, 12% Cr, 1% Ni, 0.060% N, 0.07% Mo, 0.40% V, 0.30% Nb. 2. The addition of ferrite-forming elements increases the stability during tempering; to counteract the ferritizing effect of these elements it is necessary to increase the concentration of austenite-forming elements, Ni and N. 3. Nickel lowers the Ac1 temperature; its influence is reduced considerably by the addition of 0.060% N. The steel with 0.06% N has a constant value of Ac1 (780°C), i.e., 180° above the highest operating temperature for parts manufactured from this steel. 4. The steel with 12% Cr and nitrogen has the best mechanical properties at 670°C.

Murovannaya, S.; Marmer, E.

doi: 10.1007/BF00647813pmid: N/A

Il'ina, V.; Globa, S.; Iordanskii, V.; Éntin, R.

doi: 10.1007/BF00647814pmid: N/A

1. After small plastic deformation (0.2\2-1.2%) and aging, steel 38Kh5MSFA is susceptible to strain aging, which is manifest in an increase of the ultimate strength and yield strength and decrease of elongation. The yield strength increases more than the ultimate strength. At a deformation of 0.6% and higher, followed by aging, σ0.1/σb is close to unity. The effect of strain aging on the mechanical properties is manifest in the different original conditions after low- and high-temperature tempering. However, the effect is stronger after low-temperature tempering. 2. Strain aging occurs at room temperature but is more evident at higher aging temperatures up to 300\dgC. 3. Strain aging raises the cold-brittleness threshold but has little effect on the work of crack propagation.