Metal Science and Heat Treatment

Yudin, Yu.; Maisuradze, M.; Kuklina, A.

doi: 10.1007/s11041-018-0295-1pmid: N/A

The methods of optical, electron, and atomic force microscopy are used to study the morphology of bainite formed in high-strength structural steel 25G2S2N2MA (HY-TUF) under isothermal quenching. It is shown that the temperature of the transformation affects the substructure of the bainite, which is represented by ordered layers of plates with a width obeying a lognormal distribution law. It is shown that the bainite plates consist of nanosize subplates, the size of which is determined by the temperature of the bainitic transformation.

Khlybov, A.; Vorob’ev, R.; Dubinskii, V.

doi: 10.1007/s11041-018-0296-0pmid: N/A

The effect on nonthought (partial) hardening on the microstructure, hardness and mechanical properties of steel 38KhM in different conditions (after quenching and after quenching and tempering at 200, 400 and 600°C for 2 h) is studied. Comparative analysis of the structure of the steel at different distances from the surface of a massive billet after quenching and tempering is performed.

Rokhlin, L.; Dobatkina, T.; Luk’yanova, E.; Tarytina, I.; Korol’kova, I.

doi: 10.1007/s11041-018-0297-zpmid: N/A

The aging kinetics, the mechanical properties, and the structure of cast alloy IMV7-1 of the Mg – Y – Gd – Zr system alloyed additionally with dysprosium are studied. It is shown that yttrium and gadolinium may be replaced partially with dysprosium without changes in the aging kinetics and lowering the hardening and the level of the mechanical properties of alloy IMV7-1.

Kaczmarek, Ł.; Klich, M.; Tuta, W.; Kyzioł, K.; Kuoetrowski, P.; Batory, D.; Szymañski, W.; Stegliñski, M.; Kottfer, D.

doi: 10.1007/s11041-018-0298-ypmid: N/A

The composition of wear-resistant Al/AlC/a-C:H coatings deposited on a magnesium alloy by combination of radio frequency plasma assisted chemical vapor deposition and magnetron sputtering is studied. It is shown that the mechanical properties of the coatings vary depending on the composition of the amorphous C:H layers after changing the negative bias polarization of the process from 150 to 600 V; the carbon structure may be varied from a disordered one to a graphite one as well as the sp2/sp3 bonds ratio.

Smirnov, A.; Fakhurtdinov, R.; Semenov, M.; Gromov, V.; Kupryakova, N.; Seval’nev, G.

doi: 10.1007/s11041-018-0299-xpmid: N/A

Results of a complex thermochemical treatment of test specimens from different heats of a novel high-strength heat-resistant precipitation-hardening steel microalloyed with REM are presented. The optimum chemical composition of the steel is determined with the aim to provide precipitation hardening after vacuum carburizing. In the process of finishing nitriding in glow discharge the surface hardness of the new steel increases substantially at inconsiderable decrease in the hardness of the core. The developed modes of complex thermochemical treatment exclude the appearance of such flaws as grain boundary net and excess retained austenite.

Dai, Mingyang; Li, Chaoyu; Chai, Yating; Hu, Jing

doi: 10.1007/s11041-018-0300-8pmid: N/A

Carbon steel AISI 1045 (0.45% C) is studied as a model material for rapid nitriding in a salt bath at 660°C (instead of the conventional 560°C). The methods of optical microscopy, x-ray diffraction and measurement of microhardness and corrosion resistance are used to study the microstructure and the phase composition of the nitrided layer. It is shown that salt bath nitriding shortens the process considerably and raises its efficiency; the microhardness and the corrosion resistance grow and the nitride layer acquires a γ′-Fe4N phase.

Dmitriev, A.; Korobova, N.

doi: 10.1007/s11041-018-0301-7pmid: N/A

Schemes for creating rationally directed stresses of contact friction in operations of compaction of preforms are suggested for lowering the residual porosity of powder parts and raising the efficiency of their subsequent heat treatment.

Georgiev, M.; Simeonova, T.

doi: 10.1007/s11041-018-0302-6pmid: N/A

The properties of railroad rails produced from bainitic steels are compared to those from traditional pearlitic steels. Formation and propagation of contact fatigue cracks in the rails is considered. It is shown that bainitic steels exhibit a better combination of strength and ductility characteristics than pearlitic steels.