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Kobasko N.I.,Intensive Technologies Ltd | Moskalenko A.A.,Ukrainian Academy of Sciences | Deyneko L.N.,National Metallurgical Academy of Ukraine
Materials Performance and Characterization | Year: 2014

A new method for evaluating and control of the optimal concentration of water salt solutions is proposed which is based on the possibilities of sound control system. Water salt solutions as quenchants are used in the practice to intensify hardening processes. In this paper, it is shown that water salt solutions are used for low and medium carbon alloy steels to create high compressive residual stresses at the surface of steel parts and improve mechanical properties of steels. It is underlined that quenching in water salt solutions must be interrupted at the appropriate time to prevent crack formation during fast cooling. When interruption occurs at the surface of steel parts, compressive residual stresses are formed and self-tempering takes place. During this time, at the core, a bainitic structure is formed which has enough strength and high plastic properties to prevent crack formation at the core where tensile stresses could be. It is shown that salt solutions can be also used for quenching of big steel parts like rollers and rotors. The benefits from the technology proposed are discussed in this paper. In the future, organic salt solutions can be replaced by organic salt solutions which prevent corrosion completely. © 2014 by ASTM International.

Kobasko N.I.,IQ Technologies Inc. | Kobasko N.I.,Intensive Technologies Ltd
Journal of Materials Engineering and Performance | Year: 2014

In the paper, new phenomena are discussed which were discovered during investigation of the intensive quenching processes. It is shown that in many cases film boiling is prevented completely during quenching of steel parts in cold liquids, especially in water salt solutions. In this case, the part surface temperature drops almost immediately to the liquid boiling point at the beginning of the quench and then maintains at this level for a relatively long time, i.e., the so-called self-regulated thermal process is established. A simple equation for determining the duration of the self-regulated thermal process is proposed. Thermal waves are generated during an immersion of steel parts into a cold liquid and after the self-regulated thermal process is completed. The thermal waves move in opposite direction from where the cooling process starts. The self-regulated thermal process was used to develop an original intensive quenching technology (IQ-2 process). It can be a basis for developing other new technologies such as an austempering and a martempering in cold liquids under pressure. Discovered effects of thermal waves can be used for determining a duration of the self-regulated thermal process and for reconstructing an existing theory on the double electrical layer. Practical examples of calculations of the duration of the self-regulated thermal process are provided in the paper. © 2014, ASM International.

Kobasko N.I.,IQ Technologies Inc. | Kobasko N.I.,Intensive Technologies Ltd | Aronov M.A.,IQ Technologies Inc.
Materials Performance and Characterization | Year: 2014

This paper presents an overview on the super strengthening phenomenon that takes place during intensive quenching (IQ) of steels. It is shown that for obtaining an additional strengthening of material, one should pay special attention to whether the part cooling rate within the martensite range is high enough and whether compressive stresses are formed at the surface of steel parts. For hardening high carbon alloy steels with a low martensite start temperature, a two-step quenching procedure is recommended. At the first step of quenching, the martensite transformation is delayed, and, at the second step of quenching, the part cooling rate is accelerated within the martensite range. For hardening low and medium carbon steels, an IQ-3 quench method is recommended when a so-called direct convection cooling is applied for providing a maximal cooling rate within the martensite range and maximal compressive stresses at the surface of steel parts. To calculate a part cooling rate within the martensite range, a generalized equation is provided. Data on mechanical properties for different steels proving a presence of the super strengthening effect are provided also. A practical use of the super strengthening phenomenon is discussed in the paper. © 2014 by ASTM International.

Kobasko N.I.,IQ Technologies Inc. | Batista A.A.,University of Sao Paulo | Canale L.C.F.,University of Sao Paulo | Totten G.E.,Portland State University | Dobryvechir V.V.,Intensive Technologies Ltd
Materials Performance and Characterization | Year: 2013

The cooling capacity of coconut oil, palm oil, and petroleum oil were determined by solving the inverse problem (IP) using the newly developed commercial code, IQLab. It was shown that all of the oils exhibited shock-film-boiling, film-boiling, and convection-heat-transfer modes during the quenching process. The results of these investigations are necessary when developing a global database of the cooling capacity of different quenchants. The results obtained by solving the inverse problem are compared with simplified calculation results based on cooling time-temperature data obtained by using a multi-thermocouple Inconel 600 probe. The results obtained showed that the results from both methods agreed within ±10 %. These results suggest that the standard Inconel 600 probe can be used in many cases for determining average heat-transfer coefficients occurring when using vegetable oils, such as coconut oils, palm oils, and petroleum oils as quenchants. © 2013 by ASTM International.

Kobasko N.I.,Intensive Technologies Ltd | Kobasko N.I.,IQ Technologies Inc.
Journal of ASTM International | Year: 2011

A method for optimizing the chemical composition of steels to obtain optimal residual stress distribution throughout the section of a steel part is proposed, which is based on the analytical equation for the calculation of ideal critical diameter (DI). The advantage of this method consists of the opportunity to calculate the ideal critical size for a variety of geometries on the basis of their respective continuos-cooling transformation (CCT) diagrams. Detailed discussions are provided relating to the optimal depth of the hardened layer, which provides high surface compressive residual stresses and minimal tensile stresses in the core. It is also shown that the ratio of the DI to the diameter of the part with an optimal residual stress distribution should be the same, that is, DI/Dopt=const with steel parts of varying sizes. This relationship can be used for the development of new technologies for large-sized parts based on the results obtained for small parts. The service life of steel parts increases after intensive quenching due to the formation of high surface compressive residual stresses and improved mechanical properties. During intensive quenching, the effect of additional strengthening (super strengthening) of the material is observed, which is connected with the intensification of cooling process within the martensite range. Copyright © 2011 by ASTM International.

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