Quenching in a fluid is a complex process. There are several different heat transfer mechanisms that may be occurring at the same time, with the heat transfer coefficients changes as a function of position (x, y, z) and surface temperature on the same part. This is further complicated by having multiple different parts in the same load. Agitation, racking of the parts and the quench tank design all play a role in the resultant properties and distortion of a given part. Further complicating this problem, is that there are multiple methods to measure quenching performance. In this paper, we will be describing an agitation apparatus used at Quaker Houghton for determining heat transfer coefficients as a function of agitation and surface temperature. The probe used is the ISO 9950 (ASTM D6200) Inconel probe, and the heat transfer coefficients are determined by an inverse method provided by the SmartQuench Integra software by RISE/ivf. The apparatus is examined using Computational Fluid Dynamics (CFD), and the calculated flow is compared to the measured fluid flow.

The vapor film collapse that occurs in the quenching process is complicated and unstable, these affects the heat treatment quality and its distortion. Particularly in mass production, where production costs are taken into consideration, products are often packaged in group load setting, so it is very important to know the deformation variation and distribution within that process. In order to incorporate it into the MBD technology required these days, it is necessary to predict the quality of heat treatment by CAE, shorten the product development period. However, in the past day, in order to formulate the vapor film collapse on a simulation, it was necessary to perform a very large amount of computational fluid dynamics calculation (CFD), because of a problem in computer resources and the model of vapor film collapse. In addition, this phenomenon has an complexity behavior of the phenomenon in iterative processing in mass production, which also complicates the calculation. The vapor film collapse phenomenon was visualized by using cellular automaton simulation its include the phenomena of “Vapor film thickness”, “Flow disturbance”, “Surface step of workpiece”, “the pressure for vapor film”. In this study, the Markovian property of vapor film surface vibration was clarified, and the heat treatment deformation instability of ring-shaped parts due to it was predicted.

The analysis of cooling curves obtained by immersing a probe in the quench medium has been widely used since its availability. For instance, methods described in standards such as ISO 9950 and ASTM D 6482 refer to the use of an Inconel 600 specimen which is quenched to obtain the cooling curve of a given fluid; however, spray quenching is being mostly used in induction hardening processes. In this work, the quenching characteristics of a PAG polymer at 6 and 12 % concentration were determined and compared with water as a baseline. The fluid was heated at 30 °C, while the solution flow rate was set at 90 L/min; two different quenching rings were designed and used in a laboratory-scale setting. Also, the fluid flow in the quench rings was simulated through Computational Fluid Dynamics (CFD), to obtain flow patterns inside the quenching devices. From the results obtained, the cooling rate curves showed no vapor phase, and the maximum cooling rate was found to be higher in one of the quench ring designs. The design of the quench ring device has a significant influence on the quenching characteristics of the quenchant, mainly at medium and low temperatures of the cooling rate curve.

Manufacturers regularly employ finite-element (FE) process modeling tools for the simulation of heat treatment applications, such as quenching. These tools may utilize thermal, mechanical and microstructural calculations in the analysis of part distortion and residual stresses. Heat treatment modeling workflows are challenged by the requirement for user-provided heat transfer boundary conditions, which vary based on part geometry and process parameters. Representative Heat Transfer Coefficients (HTCs) are typically reversed-engineered using experimental thermocouple data, thermal simulations and inverse optimization methods. This paper will present ‘state of the art’ developments integrating computational fluid dynamics (CFD) capabilities into the heat treat modeling environment of the DEFORM system. It will describe how CFD and thermal modeling of a quench medium is being coupled with deformation and heat transfer modeling of a part through the use of CFD-calculated, local heat transfer boundary conditions. Studies verifying the implemented CFD methods against published literature will be summarized. Application examples will show how residual stress and distortion in parts, during single-part or batch gas quenching, is made possible by coupled CFD and thermo-mechanical process modeling tools.

As Computational Fluid Dynamics (CFD) methods evolve and mature, more engineering problems are being solved through computer simulation to reduce reliance on the costly and time-consuming experimental methods. This trend is also occurring in the gear manufacturing industry, where an increasing number of quality issues related to the oil quenching process are being investigated by CFD methods to find solutions. However, while the CFD theory and numerical methods have made significant advancements, gaps still exist between the academic research and industrial applications. In the case of the oil quenching processes, the prospect of using CFD methods to visualize and study the oil flow pattern in the gear quenching tank is promising yet challenging. The obstacle to simulating the oil quenching process using CFD methods lies not in the numerical method itself for solving the Navier-Stokes equation, but in building a computer simulation model that encompasses all the geometrical details of the quenching tank, fixtures, centrifugal pumps, and gears, including all the gear teeth. This task is particularly challenging for Finite Volume Method (FVM) CFD solvers, as the computation mesh could take days or weeks to build. In this research, a new solution method based on Smoothed Particle Hydrodynamics (SPH) is introduced to simulate the oil flow in the gear quenching tank. Since SPH is a mesh-free Lagrangian method, it not only greatly simplifies the mesh generation task for building the computational models but also handles the complex physics of the free surface flow and fluid-structure interaction with great ease. In addition, the oil flow in the gear quenching tank usually is driven by centrifugal pumps whose dynamics can be simulated directly in SPH methods, as opposed to FVM methods which require complicated moving mesh computation.

Computer simulations are increasingly being used in the automotive industry to evaluate the state of stress in cylinder blocks during casting and heat treat processes. With recent advancements, it is now possible to model casting and quenching processes as well as residual stress and high cycle fatigue. However, calculating the final stress in cylinder blocks requires the integration of several software tools with different meshing topologies, numerical methods, data structures, and post-processing capabilities. The intent of this research is to develop an integrated virtual engineering environment that combines casting simulation, computational fluid dynamics, and finite element methods in order to simulate the manufacturing process from the beginning of casting, through water quenching heat treatment, to engine dynamometer testing. The computational environment is built on three CAE tools, Magmasoft, AVL Fire, and Abaqus, and required considerable amounts of research and development to validate each numerical method and the tools that facilitate data exchange between them.

This paper investigates the factors that influence quenching rates and temperature distributions in steel during dilatometry testing. In a prior study, the authors assessed the performance of the cooling system in a widely used dilatometer. The goal of the current work is to develop a cooling strategy that provides more uniform and possibly faster cooling in the same system. Several alternate quench concepts are analyzed, the most promising of which uses water-cooled tubes to deliver high velocity gas through a series of jets axially aligned with the test sample. The proposed cooling apparatus and its effect on the induction heating process are assessed using CFD, electromagnetic, and thermal analyses.

A number of modifications were made to a batch quenching process for pinion gears to reduce the amount of size change in the ID. This paper assesses the impact of adding vertical plates to the load elevator to better condition oil flow to the stacked part baskets. Data collected from pinion gears before and after the modification show a reduction in the average and range of ID bore change, indicating an improvement in quench uniformity. CFD analyses suggest that improvement is due to a significant reduction in turbulence, resulting from the addition of the vertical plates. As the authors explain, high levels of turbulence promote collapse of the vapor film that occurs at the start of the quench process, and disparity in the timing causes unwanted variation in part size change throughout the load.

Although many have had success using CFD and FEA techniques to predict residual stress and distortion in water quenched aluminum alloys, there are still hurdles in using a computational approach to manage liquid quenching processes due to the lack of a quench severity database. Quench severity is defined by the Grossman number, which does not serve as a heat transfer model for CFD simulation because it omits much of the underlying physics. In this research, a new interpretation of quench severity makes it possible to separate the heat transfer model into two groups, one computable by CFD and one requiring calibration. The objective of this paper is to parameterize the boiling model by quenching conditions and validate the model using data obtained by quenchometer testing.

Heat treatment is a common manufacturing process in automotive industry to produce high performance components such as cylinder heads and cylinder blocks. Although heat treatment incorporating a quenching process, either by high velocity air flow or water, can produce parts with durable mechanical properties, an unwanted effect of intense quenching processes is that they also induce thermal residual stress, which often is a leading cause for quality issues associated with high cycle fatigues. During product development cycle, it is not uncommon to switch between air and water quench media and change quench orientation in order to minimize residual stress. However, the choice of quench media and quench orientation is often determined by intuitive engineering judgement at best and trial-and-error iterative method at worst. With the advancement of CFD technologies, the temperature profile and history of quenching processes now can be accurately calculated. Since thermal residual stress is directly linked to non-uniform temperature distribution in the metal, spatial temperature gradient of each quenching process is evaluated to study and compare the performance of different quench media and configuration. The conclusion of this study can be used to establish engineering guidelines for future product development.

Computational Fluid Dynamics (CFD) is a widely acceptable tool for design simulations of systems. The cost of software, educated engineers, and user friendly interfaces allow for CFD products to be a viable solution in many applications of industrial furnace designs. This paper will focus on some of the ways CFD analysis has improved furnace designs, decreased the time to delivery, and meet tighter process tolerances of the heat treatment of materials.

Metallurgical properties required in aluminum alloys are highly dependent on the cooling uniformity during the quenching process. Non-uniformity during cooling is associated with piece distortion and failure. Although the quenching process is considered the most critical step during alloy heat treating, quench tank design is still based mainly on experience. Computational fluid dynamics (CFD) offers detailed understanding of the complex behavior of fluid flow and its impact on part cooling. Detailed cooling rates can then be used to predict part metallurgical properties. Although computational fluid dynamics are being used increasingly in quench tank design, there is still considerable imprecision due to assumptions that must be made. In this work, cooling curves are obtained for a 25 mm diameter 6061 aluminum cylinder probe under different conditions. Results are also obtained numerically via computational fluid dynamics. Results show the suitability for designing quench systems based on CFD simulations.

During the liquid quenching process, there are three main phases between the solid and the liquid interface: film boiling where vapor blanket covers the entire solid structure, transition or nucleate boiling, and single phase convection. The type of the quenching media, the agitation, and the flow pattern of a quench tank have significant effect on the cooling behavior during these three phases, which will affect the cooling rate, phase transformation, stress evolution and shape change of the quenched components. In this paper, transient CFD analysis using AVL FIRE is coupled with heat treatment analysis using DANTE to simulate an oil quench hardening process of a test gear made of Pyrowear 53. The gear is carburized prior to quench hardening. During the coupling analyses, the heat flux between the gear and the oil calculated in the CFD model is applied to the solid heat treatment model, and the gear surface temperature predicted by the heat treatment model is passed back to the transient CFD model. The aforementioned CFD tool is capable of considering the entire quenching domains without considering phase transformations in the quenched components. In the present case the gear is treated with a finite element tool in combination with DANTE to account for the latent heat release, which slows down the cooling. The relations between carbon content, temperature field, phase transformation, internal stress, and shape change during quenching are explained from the heat treatment modeling results. The coupling of CFD and heat treatment analyses provides a more robust application of computer modeling in the heat treatment industry.

Extensive steady-state flow boiling heat transfer data have been collected for both water and oil using a test rig that allows for control of the primary variables of fluid velocity, fluid temperature, surface temperature, and surface orientation. Using the resulting database, functional relationships for boiling heat transfer trends have been determined. These boiling heat transfer relationships have been incorporated into the Ansys-Fluent commercial CFD package using a user-defined function (UDF). This software combination provides a simulation tool capable of approximating the quenching of metal parts by applying a situationally correct heat flux at each point in the part surface throughout the quench cycle. No manipulation of model tuning parameters is required. Simulation predictions are compared to test data collected for a cylindrical forging.

Air quenching is a common manufacturing process to produce high strength metal component by rapidly cooling heated parts in a short period of time. With the advancement of finite element analysis (FEA) methods, it has been possible to predict thermal residual stress by computer simulation. However, the accuracy of FEA calculation is bounded by the accuracy of the temperature data, acquired either by thermocouple measurement, experimentally calibrated heat transfer coefficient (HTC) method, or computational fluid dynamics (CFD) calculation. While CFD methods have gained popularity, the practicality of CFD method is reduced by tedious mesh generation and costly computation that is only feasible to be performed on a supercomputer. When quenching media is a gas-phased fluid and quenching flow is steady, the flow and temperature fields exhibit certain characteristics that could lead to the development of enhanced HTC method that is more computation efficient and yet produces more accurate temperature data.

Quenching is a key step in most heat treating operations. Sufficient fluid velocity is required to achieve the desired material properties, while even flow is needed to ensure low distortion and good part uniformity. It is not intuitively obvious, however, which agitation method will best achieve those goals. Computational fluid dynamics (CFD) modeling techniques can provide the insight needed to evaluate potential agitation designs and ultimately develop a robust agitation system. For a shallow quench tank with submerged impellers, a number of different concepts for providing agitation to a load of ring-like parts were investigated. Design parameters included the number and arrangement of the impellers, baffles and turning vanes, and the rotational direction of the impellers. The final design provided agitation that was significantly improved in comparison to that in the initial concept.