The Influence of Thermocyclic Treatment on the Structure and Mechanical Properties of Pseudo-Alpha Titanium Alloys for Steam Turbine Blades

The influence of thermal cycling treatment of pseudo-α-titanium alloys OT4 and VT20 on their structural and substructural characteristics, as well as their mechanical properties is considered. A significant change in structural characteristics is established. This contributes to an increase in the strength properties of alloys with satisfactory ductility and high-temperature strength.

Структурные особенности наноструктурного эквиатомного сплава TiNi при многократных мартенситных превращениях

The paper describes in detail a study dealing with the influence of multiple martensite transformations on the equiatomic alloy of the TiNi system microstructure. Thermocyclic treatment of the equiatomic alloy in the nanocrystalline state obtained by the intensive torsional plastic deformation method was carried out.

Effect of different types of thermal cycling treatment on mechanical properties of 44NKhTYu elinvar alloy

The results of the effect of experimental regimes of thermocyclic treatment of elinvar 44NKhTYu alloy on its mechanical properties are presented.

Effect of heat treatment on non-stationary modes on structure of pseudo-α-titanium alloys used for steam turbine blades

The effect of thermocyclic treatment of pseudo-α-titanium alloys OT4 and VT20 on their structural and substructural characteristics is considered. Signifi cant change in structural characteristics is established, this contribu tes to increase in the strength properties of alloys with satisfactory ductility and heat resistance.

Effect of Thermocyclic Treatment with Different Cooling Rates on the Mechanical Characteristics of 42CD4 Low-Alloy Steel

The aim of this study was to investigate the influence of thermo-cyclic treatments on the mechanical characteristics (Hardness and Resilience) of low-alloy 42CD4 steel. Thermocyclic treatment on 42CD4 steel was operated for four cycles at 850 °C for 30 min. After each cycle, the steel sample was cooled in different medium (open air and water) in order to check the effect of the cooling rate on the microstructure characteristics. It was found that the cooling rate can affect the mechanical characteristics of the steel. The hardness values of steel cooled in water were higher than those of steel cooled in air. Additionally, there was an increase in the resilience of steel sample with the increase of thermocyclic number.

The effect of hydrogen on the properties of polymorphic metals during thermal cycling near the polymorphism temperature

The effect of hydrogen on the numerous properties of metals is known. In general, it is associated with the structure of its atom, which consists of a proton and an electron. Getting into the metal, it turns into an elementary particle, which has its own special properties. The paper considers the case of the interaction of hydrogen with polymorphic metals during their thermal cycling around the temperature of polymorphism. The main metal of this study is iron. It was revealed that during thermocyclic treatment in a hydrogen medium in iron during cooling, the yield strength decreases catastrophically by 3–4 orders of magnitude (up to a certain time, it was considered one order). In the absence of hydrogen (thermal cycling in an inert atmosphere), such changes did not occur. It was determined that when the crystal lattice restructuring from the γ phase to the α phase, the solubility of hydrogen decreases and it accumulates at the transformation boundary. Depending on the process parameters (cooling rate, saturation pressure, overheating temperature, symmetry relatively to the transformation point, etc.), various types of involuntary metal flow can be obtained. Besides the iron, other polymorphic metals - manganese, cobalt, titanium, zirconium - have been investigated. The deformation effect was observed only for manganese. Cobalt, due to another mechanism of polymorphic transformation, can not be deformed. Hydride-forming metals under normal conditions of cycling are severely cracked (the formation of hydrides), their small deformation is possible under very low hydrogen pressure. The reason for the formation of such properties is the creation of a special zone on the boundary of two phases – the H-layer. The concentration of hydrogen in the H-layer can reach tens of atomic percentages. This is confirmed by numerous experiments on fixing a new phase (N-martensite) and change the physical and mechanical properties of iron. In the deformation process, protons actively interact with defects in the lattice, which causes the pores formation inside the metal. These studies were awarded a diploma for the opening No. 313 authors V.Yu. Karpov and V.I Shapovalov.