New Approach In Modifying Quenching Processes Based On Possibility Of Controlling Steel's Surface Temperature By Insulating Layer

In the paper is shown a possibility to govern surface temperature of steel parts during quenching by controlling the thickness of the insulating layer. That results in developing the new quenching technologies like austempering process via cold liquids. The investigations were performed with a low concentration of the polyethylene in cold water using 20 mm cylindrical probe instrumented with two thermocouples. It is established that with the increase concentration of polyoxyethylene in cold water (beginning from 0.001 %) different heat transfer modes are observed resulting in the elimination of film boiling process at 0.001 % concentration, increasing surface temperature of probe during self – regulated thermal process, periodical changing of heat flux densities, slow cooling of surface temperature like in oil when concentration reaches 1 % polyoxyethylene in water, and so on. It is underlined that low concentration of polyoxyethylene in water can serve as an excellent quenchant for accelerated and uniform cooling of steel parts decreasing by this way the cost of a coolant. In this case accelerated cooling should be interrupted at proper time to provide optimal hardened layer afterr quenching. Such approach guarantees increasing service life of steel parts after accelerated cooling with the significant decrease of their cost and eliminates carburization process, The technology can be used for hardening large steel parts like large wind mill gears, large bearing rings, etc

A Method for Optimizing Chemical Composition of Steels to Reduce Radically Their Alloy Elements and Increase Service Life of Machine Components

A method for optimizing chemical composition of steel is proposed and a correlation is established to reduce cardinally alloy elements in existing steel grades that results in high compressive residual stresses at the surface of intensively quenched steel parts and increasing strength and ductility of material due to super- strengthening phenomenon. The algorithm of optimization consists in reducing alloy elements in existing alloy steel in 1.5 – 2 times and then lowering step-by-step content of steel, beginning from the most costly alloy element and ending the most cheaper one, until established correlation is satisfied. The range of reduction is minimal and during computer calculations can be chosen as 0,001wt%. The proposed approach can save alloy elements, energy, increase service life of machine components and improve environmental condition. The method is a basis for development of the new low hardenability (LH) and optimal hardenability (OH) steels

Effect Of Free Electrons In Steel On Its Quenching Process In Water And Water Salt Solutions

In the paper some phenomena of physics taking place during quenching steel in liquid media is widely discussed. It is shown that a double electrical layer is responsible for unknown impulse like effect constantly observed during quenching probes in electrolytes. It can be used for transient nucleate boiling process evaluation that is a basis for designing intensive quenching technology known as IQ-2 process. Early published phenomena of physics such as a poker effect, two stage cooling, and optimal concentration of electrolytes have the common nature – free electrons in metal. The observed phenomena of physics can be governed by hyperbolic heat conductivity equation with the appropriate initial and boundary conditions instead of parabolic heat conductivity widely used equation. At present time, fortunately, mathematicians started seriously investigations in this area by solving hyperbolic heat conductivity equations which can release in the future more new unknown phenomena to be widely used in the practice

Investigation of Batch Intensive Quenching Processes When Using Hydrodynamic Emitters in Quench Tanks

The paper discusses patented in Ukraine a new intensive quenching IQ–2 technology based on film boiling resonance effect [1]. Namely, the paper discusses improving of the batch intensive quenching (IQ) process known as IQ-2 method by the use of hydrodynamic emitters installed in quench tanks. The hydrodynamic emitters produce oscillating waves in the quench media with the frequency of the film boiling process creating a resonance effect. Two- and three-step IQ-2 processes are considered. Specifics of the heat transfer during the IQ-2 process are presented with focusing on the first stage of quenching where film and nucleate boiling processes are taking place. Examples of production IQ-2 equipment and loads processed are also presented. Application of hydrodynamic emitters in the IQ water tanks in addition to currently used propellers is considered in details. It is shown that the proposed new method can fully eliminate the film boiling process resulting in significant reduction of part distortion during quenching. Further evaluation of the proposed method is needed for its implementation in heat treating practice

Designing Of Advanced And Original Austempering Processes Based On Thermal Science And Engineering Physics Approaches

In the paper, a small concentration of inverse solubility polymers in water and other liquid media is recommended to eliminate film boiling by means of reducing initial heat flux density. Quenching steel parts and tools in a small concentration of water solutions under pressure allows performing austempering process just using cold liquids. Its essence consists in coinciding martensite start temperature MS with the average temperature of self-regulated thermal process during nucleate boiling mode and further immediate transferring steel parts for tempering at the temperature which exceeds value MS. The new technology increases the service life of austempered workpieces by more than two times, saves alloy elements, is suitable for larger metallic components, improves environmental conditions, since instead of melted salts and alkali, plain water and water salt solutions can be used. The new austempering process can be used in forging shops to obtain super-strengthened materials in order to switch from alloy steel to plain carbon steels. And it can be also widely used for obtaining nano - bainitic structure in plain carbon steels resulting in saving alloy elements and improving mechanical characteristics of materials

Cooling Intensity of Inverse Solubility Polyalkylene Glykol Polymers and Some Results of Investigations Focused on Minimizing Distortion of Metal Components

Poly(Alkylene Glycol) polymers of inverse solubility (PAG) provide ideal uniform cooling for minimizing distortion and preventing crack formation during hardening machine components and tools. However, in spite of ideal cooling, from time to time, a big distortion takes place during hardening process. A reason for a big distortion development during hardening in PAG solutions is explained and an idea how to fix the problem is suggested. It is shown that at the end of cooling coating can be locally dissolved by a cold water flow creating local open area where martensite transformation starts first. Due to greater specific volume of martensite, it creates a big distortion. To solve the problem, one should interrupt cooling process or stop agitation before insulating coating is dissolved. To perform correctly proposed technology, cooling intensity of inverse solubility PAG polymers of 1–20 % were investigated on the basis of use of regular thermal condition theory. As a result, dimensionless effective numbers Kn were obtained for recipes development. A technique for solving the problem is proposed by author. Examples of calculations are provided

Liscic/petrofer Probe to Investigate Real Industrial Hardening Processes and Some Fundamentals During Quenching of Steel Parts in Liquid Media

In the paper some unusual processes are considered during quenching such as self-regulated thermal process when metallic probe is covered by insulating polymeric layer, oscillation of temperature in surface layers of probe, creation a “shoulder” when quenching in polymer solution, possibility to perform austempering process just in cold liquids. Above mentioned processes build a basis for the new intensive quenching technologies and can bring a great benefit for heat treating industry when further carefully investigated. It is shown that initial temperature gradients, which cannot be governed by classical law of Fourier, can be tested by Liscic/Petrofer probe, etc. The paper discusses how organize such International investigation to satisfy contemporary practical needs and solve unsolved problems of science in the field of quenching. Also, the results of investigations can be used for software designing and cooling recipes development during quenching steel parts in liquid media. It makes a great progress because at preset time only cooling curves and cooling rates are available that are used for comparable purpose and cannot be used for recipes development

Research On Maximizing Critical And Reducing Initial Heat Flux Densities To Eliminate Any Film Boiling And Minimize Distortion During Quenching

In the paper the results of testing three types of FUCHS oils: Thermisol QH 120, Thermisol QH 10 and Thermisol QB 46 are discussed. The main attention is paid to critical heat flux densities evaluation because they create a basis for optimizing cooling intensity of any liquid quenchant. In the paper is underlined that any film boiling during quenching is undesirable since it is a reason for big distortion and non-uniform surface harness. It is shown that intensive quenching decreases distortion of steel parts during quenching. To eliminate film boiling during quenching in mineral oils, optimal temperature of oil should be chosen which maximize the first critical heat flux density and special additives should be used to decrease initial heat flux by creating surface micro-coating. Along with the evaluation of heat transfer coefficients, critical heat flux densities inherent to liquid quenchant must be measured first to optimize quenching processes. International DATABASE on cooling characteristics of liquid quenchants must include critical heat flux densities, initial heat flux densities, and heat transfer coefficients allowing optimizing and governing quenching processes

New Era in Designing and Governing Cooling Intensity of Liquid Quenchants to Decrease Distortion During Hardening of Steel Parts

It was proved in last decade that very intensive and uniform cooling eliminates quench crack formation and significantly decreases distortion of quenched steel parts as compared with their slow cooling in mineral oils. That opened a new era in design ing and governing cooling intensity of liquid quenchants for strengthening steel parts and decrease their distortion after quenching. The new approaches were developed by authors to provide accelerated and uniform cooling steel parts during quenching by creation on their surface thin insulating layers. For this purpose low concentration of water polymer solutions of inverse solubility are used as a quenchant. More information on cooling intensity of Poly (Alkylene Glycol) polymers (PAG) solutions one can find in a well known book (Totten et al., 1993). Along with decreasing distortion of steel parts, such approach decreases cost of bath’s coolant which less affects environment. It is shown in presentation that accelerated cooling should be interrupted at proper time to provide self tempering, fix compressive residual stresses, decrease more distortion and prevent quench crack formation. To govern process of quenching and make cooling interruption, software IQCalc2 was developed