In this study, we developed the heat treatment simulation that can consider the difference in phase transformation behavior and strength characteristics in response to heterogeneous composition by calculating the TTT diagram and stress-strain curve corresponding to the composition at each position of the simulation model.

A patented DANTE Controlled Gas Quench (DCGQ) process was developed for high precision distortion control during quench hardening. The DCGQ process follows a recipe of quenching time and the ambient gas temperature designed by computer modeling, with a specified maximum allowed temperature difference in the part section during the martensitic transformation.

This study derived the mechanism by which previous processing processes affect heat treatment quality, especially “variation in deformation,” and clarified a method for predicting it using heat treatment simulations. We investigated the metal structure and residual stress at the completion of machining for a round bar and performed a heat treatment deformation simulation with this in mind and were able to reproduce the heat treatment deformation.

This study investigates the effect of vapor blanket duration in quenching oil on the mechanical properties and distortion of JIS-S45C carbon steel and JIS-SCM435 low-alloy steel. Four types of heat treatment oils with varying vapor blanket stage lengths were tested on key-grooved cylindrical specimens. Results indicate that quenching oils with longer vapor blanket durations produced smaller distortions, while oils with shorter durations caused larger distortions.

This study presents a method to reduce thermal distortion in tubular automotive stabilizer bars by replacing batch furnace heating with individual conductive heating and implementing a press-quenching technique with a seven-point clamping fixture. Using finite element analysis, researchers optimized the clamping system to maintain critical dimensional tolerances while addressing the challenges of inhomogeneous temperature distribution through a programmed current profile. Statistical analysis confirmed significant improvement in dimensional stability compared to conventional quenching.

To develop a behavior model, properties such as Young's modulus, viscous stress, kinematic hardening, isotropic hardening, yield strength and transformation-induced plasticity parameter (TRIP) for austenite and martensite were determined using a specially developed experimental set-up.

This work serves to expand upon the fundamental idea of high convection quenching (HCQ), examining alternative methods to destabilize vapor barrier formation in liquid quenchants. Namely, ultrasound in combination with a brine solution is applied to realize fast yet controllable quenching conditions.

This work aims to gain a deeper understanding of the mechanisms impacting distortion by working out the relationships between flow inhomogeneities in an industrial quench tank and the distortion of gear shafts. For this purpose, oil flow-modifying measures are used to induce specific shape changes on case-hardened gear shafts from commercial vehicles. The shape changes are quantified by runout and coordinate measurements.

While researchers have attempted to characterize heat transfer coefficients in spray quenching standard immersion probes, the high surface heat transfer creates steep thermal gradients that cause measurement lag and underestimate coefficients. These inaccurate measurements significantly impact predictions of microstructure, dimensions, and residual stress distribution. This study examines thermal gradients across different probe diameters and materials to determine optimal probe geometry for accurate heat transfer coefficient measurement and calculation.

In this study, a single-sided carburized Almen strip made of Pyrowear 675 is used to investigate the effect of phase transformations on quench hardening distortion. Computer modeling is used to analyze the collected experimental data and demonstrate the underlying principles of distortions and residual stress.

This work aims to contribute to the optimization of the simulation process in the heat treatment industry. Cooling curves of a polyacrylate-based (ACR) polymer solution at a concentration of 9 and 12 %, using an axial flow rate of 1.30 L/min on an immersion system and a fluid temperature of 45 °C were acquired and analyzed. Air quenching was also used to compare the polymer quenching conditions.

This study investigates quenching effects on horizontally oriented hollow cylinders, a common industrial configuration for large tubular geometries. Researchers analyzed thermal histories at various positions on the cylinder, accounting for the pre-immersion air transfer that creates non-uniform conditions. Using inverse heat transfer analysis, they calculated transient heat fluxes along both outer and inner surfaces, revealing uneven cooling patterns. The results demonstrate thermal gradients both during air transfer and after immersion, with findings compared to previous studies of horizontal plates and vertically quenched cylinders.

In this work, we report the evolution of heat extraction from probes of three different geometries: flat-end, conical-end and hemispherical-end cylinders, characterized through video-recordings and cooling curves.

This study investigates the stress evolution and microstructural changes in TC4 titanium alloy through isothermal gradient solution quenching (900~1000°C solution treatment, water quenching at room temperature and 60°C), followed by annealing at 700~800°C and aging at 500~550°C.

Oil, polymer, and gas quenching have long been used due to their effectiveness in cooling components rapidly to achieve the desired microstructure. However, they often cause distortion, complicating post-manufacturing corrections. A newer approach, Four-Dimensional Quenching (4DQ), uses high-pressure gas as the quenching medium and allows precise control over gas flow. This method significantly reduces distortion and ensures consistency across components.

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.

Induction surface hardening is a process often used in industrial applications to efficiently increase the lifetime of components. Recently, this process has been enhanced with the inductive short time austempering process, creating a martensitic-bainitic microstructure. It is well-known that in homogeneous mixed microstructures, an optimally adjusted volume fraction of bainite can significantly increase the lifetime of the components even further. Regarding inductive short time austempering, there is a lack of knowledge in characterizing and differentiating graded microstructures, which occur due to the temperature gradients within the process. Therefore, three methods were investigated: the analysis of the grayscale profile of metallographic sections, the hardness profile and the full width at half maximum (FWHM) profile from the intensity curve (rocking curve) of the X-ray diffraction pattern. These methods were initially applied to homogeneous structures and evaluated. The findings were then transferred to graded microstructures. Finally, the graded microstructures could be differentiated both via the hardness profile and the FWHM value, while the grayscale analysis only allowed qualitative statements to be made. It became evident that both the volume fractions and their structure are crucial for subsequent mechanical characterization. Since the martensitic microstructure is easier to identify, it serves as a reliable reference for evaluating the mixed microstructure. In summary, these findings offer the foundation for further characterization of graded martensitic-bainitic mixed microstructures.

Martensitic stainless steels are an important group of steels for applications as knives, tools & molds and highly loaded parts in the food and plastics processing industry as well as for machinery components. Their typical hardening consists of quenching and (multiple) tempering (Q&T). As many of these steels contain at least smaller amounts of retained austenite (RA) after quenching, partitioning of carbon and nitrogen from the martensite into the RA can take place during tempering, changing it from Q&T to quenching & partitioning (Q&P). This contribution provides as systematic overview of such partitioning effects on the microstructure like the amount and stability of retained austenite as well as on subsequent effects on material properties such as hardness, toughness, strength and ductility. The various effects were investigated on several steel grades and cover also the effect of variation in heat treatment parameters like austenitizing temperature, quench rate, quenching temperature, number, duration and temperature of the tempering, respectively partitioning. The results clearly show that partitioning dominates over tempering effects at temperatures up to 500°C. Higher quenching temperatures can increase the RA-content similar to higher austenitizing temperatures. Lower quench rates can reduce it due to carbide (nitride) precipitation. Rising tempering (partitioning) temperatures up to 400°C enhances the austenite stabilization. Higher amounts of RA with reduced stability promotes transformation induced plasticity (TRIP), providing the possibility to optimized ductility and tensile strength but reduces yield strength. Increased amounts of RA with sufficient stability increases impact toughness at slightly reduced hardness. Increasing the tempering temperature above 500°C in contrast promotes, after a certain nucleation time, carbide and nitride precipitation, resulting in the elimination of the retained austenite and therefore a typical tempering condition.

Gas carburizing with quenching is one of the most useful heat treatment processes for steel parts. However, after quenching distortion is still occurs. The nitriding and nitrocarburizing are the surface hardening heat treatment methods with low distortion, but these methods require the long treating time to obtain a thick hardened layer. Austenitic nitriding and quenching (ANQ) solves these problems. In ANQ process, nitrogen is infiltrated into the steel parts in austenite phase, and they are quenched to harden. The ANQ process can also be applied to cheap low carbon steel such as the Cold Rolled Carbon Steel Sheet. In this study, the effect of ANQ on mechanical properties was examined. For infiltrating the nitrogen into the steel parts, the steel parts were heating to 750°C or higher in an ammonia atmosphere and heating to 750°C or higher in a nitrogen glow discharge. After the ANQ process, hardness profiles, structure, nitrogen and carbon concentration profiles were observed. Also, distortion, tribological properties, impact value and fatigue strength were examined. The effective case depth, which is treated by ANQ, is larger than the effective case depth of gas nitrocarburizing for same period of time. Distortion of ANQ is much smaller than that of gas carbonitriding, and it is almost equal with that of gas nitrocarburizing. The seizure load is same as with other surface hardening heat treatment processes. The wear loss of ANQ is a lower, in the amount of about 1/2 that of the carbonitrided specimen and 1/3 that of the gas nitrocarburized specimen. The ANQ is an effective heat treatment process for parts which require wear resistance. The tempering softening resistance is improved by nitrogen infiltration. ANQ also improves the impact value and fatigue strength.