Metal Science and Heat Treatment

Gorbunov, V.; Gratsianov, Yu.; Izotova, G.

doi: 10.1007/BF00654925pmid: N/A

Kazennikova, A.; Makarov, K.; Sergeev, V.

doi: 10.1007/BF00654926pmid: N/A

1. After optimal TMT, domains of magnetic interaction appear in the form of a band system only in single crystals of the YuNDK24 alloy. 2. Rearrangement of the domain structure in single crystals of alloy YuNDK24 is observed in fields corresponding to the steep sections of the hysteresis loop. 3. The domain structure depends on the magnitude and the uniformity of the demagnetizing field; the more intense and the less uniform the field, the more distinct the domain structure.

Povolotskii, E.; Mikheev, N.

doi: 10.1007/BF00654927pmid: N/A

1. The susceptibility of Magnico alloys (ANKO4 or YuNDK25A) to TMT depends on the aluminum concentration. Variations in the aluminum concentration of the alloys have a great influence on the effectiveness of TMT. Alloys with less than 7.2% Al are almost insusceptible to TMT. Alloys with∼8% Al are most susceptible to TMT. 2. The susceptibility of Magnico alloys to TMT depends on the relationship between the Curie temperature and the beginning temperature of the dispersedβ →β −β 2 decomposition. This relationship also depends on the aluminum concentration. With 6–9% Al the variation of the Curie temperature is extreme, while the variation of the initial decomposition temperature is monotonic. The requirement that the Curie temperature exceed the initial decomposition temperature, which is necessary for susceptibility to TMT, can be attained only with aluminum concentrations above 7.2–7.5%. 3. The temperature range in which the field is applied during TMT of Magnico alloys under production conditions should be chosen with possible variations in the aluminum concentration kept in mind. This temperature range amounts to 120° (870–750°C).

Sadovskii, V.; Bukhalov, A.; Smirnov, L.

doi: 10.1007/BF00654928pmid: N/A

1. The inheritance of strengthening during repeated quenching is absent in the case where the formation of austenite during heating occurs by the ordinary diffusion mechanism connected with complete recrystallization. 2. The inheritance of strengthening during repeated quenching of previously strengthened steel (quenching, TMT, or cold working) is evident in those cases where the formation of austenite with very rapid or very slow heating during repeated quenching occurs, by the mechanism characterized by structural inheritance. 3. The inheritance of strengthening during repeated quenching of structural steels makes it possible to obtain an ultimate strength 15kg/mm2 and a yield strength 20kg/mm2 higher with very rapid heating and 6 and 12 kg/mm2 higher with very slow heating (at ultimate strengths of 150–200 kg/mm2) as compared with ordinary quenching.

Bernshtein, M.; Mints, I.

doi: 10.1007/BF00654929pmid: N/A

1. Intermediate heating of cold-rolled steel 12Kh1MF to 500°C leads to a polygonized structure resistant to recrystallization at normalizing temperatures. Under these conditions the decomposition of the austenite solid solution during normalization occurs preferentially by the bainitic mechanism with retention of the substructure developed in the ferritic grains. After PTMT one observes an increase of the time to failure by a factor of three as compared with SHT under the same testing conditions. 2. It was shown that the substructure is inherited after recrystallization in those cases where a polygonization substructure is formed, which is fixed by the dispersed precipitates.

Bashchenko, A.; Mel'nichenko, N.

doi: 10.1007/BF00654930pmid: N/A

An increase of the austenitizing temperature with TMT of secondary-hardening steel 40Kh5MVFS, as in the case of SHT, increases the strength up to a certain limit. The negative influence of the increase in the austenite grain size on the ductility of the steel is smaller in the case of TMT than in SHT.

Gulyaev, A.; Kim-Khenkina, A.

doi: 10.1007/BF00654931pmid: N/A

1. The use of HTTMT and vacuum melting increases the resistance of steel to brittle fracture and lowers the cold brittleness threshold, while increasing the work of crack propagation. 2. After HTTMT the highest strength of vacuum heats is about 240 kg/mm2 at which the steel retains more or less satisfactory values of ductility and plasticity. After SHT of open heats this same strength is approximately 180 kg/mm2. 3. We found no advantage of LTTMT over such a simple method of increasing the strength as increasing the carbon concentration (by about 0.1%).

Bernshtein, M.; Kaputkina, L.; Kanev, V.

doi: 10.1007/BF00654932pmid: N/A

1. HTTMT intensifies two-phase decomposition of martensite in the process of quenching (increases the amount of low-carbon martensite) and favors partial transformation by the intermediate mechanism in the steels investigated. 2. HTTMT affects the tempering of martensite. It inhibits single-phase decomposition and increases the stability of the two-phase condition of the solid solution. During tempering after HTTMT the tetragonal solid solution is retained to higher temperatures. This may be one of the reasons that the effect of HTTMT is retained at high tempering temperatures. 3. The good combination of the mechanical properties after HTTMT is due to the fragmented stable structure of martensite, the interaction of carbon with defects, and the optimal redistribution of carbon in the martensite crystals. 4. The changes in the structure during HTTMT are resistant and retained at high tempering temperatures and during repeated heat treatment.

Belkin, M.; Sologub, V.; Venzhega, E.

doi: 10.1007/BF00654933pmid: N/A

1. Electroslag remelting increases the fatigue strength of steel 9Kh. 2. The use of electroslag remelting is most effective after HTTMT.

Trayanov, G.; Nikitina, A.

doi: 10.1007/BF00654934pmid: N/A