Metal Science and Heat Treatment

Gol'dshtein, Ya.; Zaslavskii, A.

doi: 10.1007/BF00705186pmid: N/A

Kobasko, N.

doi: 10.1007/BF00705187pmid: N/A

1. The temperature fields of cylindrical bodies in the process of quenching in a moving or still liquid under excess pressure were calculated on the basis of a mathematical model proposed earlier. 2. Analysis of the solutions obtained with the computer showed that during nucleate boiling the temperature on the surface of the cooled body changes negligibly, differing slightly from the saturation temperature of the cooling liquid, which makes it possible to control the boundary conditions by changing the pressure, i.e., slow down or speed up the transformation of austenite to martensite. 3. The change in the value of ξ0 can be neglected in simplified calculations, and it can be considered that the temperature on the surface is constant during nucleate boiling. This makes it possible to treat the experimental and theoretical data by means of the theory of normal thermal conditions. The data calculated by this method show that the generalized Biot number is a constant value that is independent of the dimensions of the cylinder and agrees with the experimental data. 4. The generalized Biot number can be used only in calculating the cooling time of different bodies. In calculating the temperature fields it is necessary to solve nonlinear boundary problems of thermal conductivity.

Gurenko, V.; Kats, L.; Volkov, V.; Morozov, Yu.; Mochalin, N.

doi: 10.1007/BF00705188pmid: N/A

Smol'nikov, E.; Simonenko, A.

doi: 10.1007/BF00705189pmid: N/A

1. Heating of steel parts in a high-temperature induction salt bath with a graphite crucible results not only from the heat from the surrounding fused salts but also from the electromagnetic field that occurs in the crucible. 2. The heating curves for steel parts in induction and electrode salt baths are of the same shape in the initial and middle sections. A difference in the curves is observed in the last stage of heating. In an induction salt bath the temperature in the center of the piece reaches the temperature of the fused salts, while in an electrode salt bath it remains 10–15° below the temperature of the fused salts. 3. The through heating time for steel parts is 30–50% smaller in an induction salt bath with a graphite crucible than in an electrode salt bath. 4. The effect of preliminary heating and the temperature of the salts is the same in both baths — the through heating time decreases as they increase. 5. The through heating time for samples of steels R6M5, R12, and R18 is practically the same with an identical temperature of the fused salts.

Rusin, P.; Pustovoit, V.; Dombrovskii, Yu.

doi: 10.1007/BF00705190pmid: N/A

Dymov, G.; Golovinov, M.; Kesel'man, A.; Myachina, A.

doi: 10.1007/BF00705191pmid: N/A

1. The expediency of quenching aluminum alloys in a fluidized bed must be decided in each specific case. One must take into account the hardenability of the alloy, the thickness of the piece, the properties, warping, and internal stresses resulting from quenching. 2. On the basis of our results and data from [2, 3] we suggest that further tests of quenching in a fluidized bed be made on alloys AK4-1, AD31, V93, and AV.

Koshelev, P.; Nikitin, P.; Katkova, V.

doi: 10.1007/BF00705192pmid: N/A

1. Precipitation-hardened alloy 36NKhT Yu has high strength, good ductility, a stable structure, low sensitivity to stress concentrations at low temperatures, and can be used for highly stressed components of cryogenic apparatus. 2. Austenitic-ferritic steels 15Kh18N12S4T Yu and 12Kh21N5T are characterized by satisfactory strength, ductility, and toughness at temperatures down to 4°K. 3. Steel 0Kh20N4AG10 has low ductility and is sensitive to stress concentrations at temperatures below 77°K.

Kasinskaya, L.; Zhuravleva, L.; Zhadan, T.; Pavlov, N.; Konyukhov, A.

doi: 10.1007/BF00705193pmid: N/A

doi: 10.1007/BF00705194pmid: N/A

Zaitsev, A.; Korotkov, N.; Lazarev, É.

doi: 10.1007/BF00705195pmid: N/A

1. We investigated the kinetics and mechanism of oxidation of low-alloy molybdenum and molybdenum-tungsten alloys in air at 400–1100°. 2. Alloying of molybdenum with tungsten increases its resistance to oxidation up to 600–700° at higher temperatures (800–1100°) the favorable effect of tungsten is suppressed by intensive evaporation of MoO3. 3. The addition of carbon increases with oxidation rate due to formation of gaseous CO and CO2, which disrupt the continuity of the oxide film. Small additions of zirconium and titanium have practically no effect on the oxidation rate of the alloys above 600°. At lower temperatures titanium reduces, and zirconium increases, the oxidation rate of molybdenum.