Quench Factor Research Articles

Prediction of properties distribution of 7B50 alloy thick plates after quenching and aging by quench factor analysis method

In the present work, continuous cooling curves were accurately measured by the modified Jominy specimen of 7B50 alloy during water-spray quenching tests. Besides, the time–temperature–properties (TTP) curves of this alloy were obtained during isothermal treatments. Based on the accurate cooling curves and TTP curves, the hardness distribution along the thickness direction of 7B50 alloy thick plates was predicted by quench factor analysis method. It is found that the quench sensitive temperature range of 7B50 alloy is 240–410 °C, the nose temperature is 335 °C, and the incubation period at the nose temperature is about 0.87 s. When 7B50 alloy was isothermal treated at 180–400 °C after solid solution treatment (470 °C for 1 h followed by 483 °C for 2 h), the exponent (n) in the Johnson–Mehl–Avrami equation is close to 1 until transformed fraction of new precipitates is up to 60%, indicating that new precipitates first grow into rodlike shape and then coarsen or thicken. When the distance is less than 65 mm from the spray quenching surface of the modified Jominy specimen, the deviation between the predicted and measured hardness is less than 2.7%, confirming the quench factor analysis method as the feasible way to predict the hardness distribution along the thickness direction of 7B50 alloy thick plates. When the distance from the spray quenching surface is 25 mm, the average cooling rate in quench sensitive temperature range is 9.93 °C·s−1, while the quench factor (τ) is 9.89 and the corresponding predicted hardness is HV 185.1 equivalent to 97.3% of the maximum measured hardness of 7B50 alloy in T6 temper.

Low energy recoil detection with a spherical proportional counter

We present results for the detection of low energy nuclear recoils in the keV energy region, from measurements performed with the Spherical Proportional Counter (SPC). An 241Am-9Be fast neutron source is used in order to obtain neutron–nucleus elastic scattering events inside the gaseous volume of the detector. The detector performance in the keV energy region was measured by observing the 5.9 keV line of a 55Fe X-ray source, with energy resolution of 10% (σ). The toolkit GEANT4 was used to simulate the irradiation of the detector by an 241Am-9Be source, while SRIM was used to calculate the Ionization Quenching Factor (IQF), the simulation results are compared with the measurements. The potential of the SPC in low energy recoil detection makes the detector a good candidate for a wide range of applications, including Supernova or reactor neutrino detection and Dark Matter (WIMP) searches (via coherent elastic scattering).

Effect of Precipitation During Quenching on the Prediction of the Mechanical Properties of Al-5 Pct Cu Alloy After T6 Treatment

The mechanical properties of Al-5 pct Cu cast alloy, one of the heat-treatable aluminum alloys, depend on the quenching rate and aging conditions. The effect of precipitation during quenching cannot be ignored for large and thick-walled components, although it is generally assumed that no precipitates form during cooling. In this article, a non-isokinetic model, considering the strengthening effects of precipitation during quenching and aging, was proposed to describe the evolution of minimum strength based on fully precipitating tests and transmission electron microscopy observations. Moreover, a comprehensive quench factor analysis, integrated with the non-isokinetic model, was conducted for the Al-5 pct Cu cast alloy using isothermal quench tests. Finally, the integrated model of the mechanical property was validated under various quenching conditions, including water at 353 K (80 °C), air at room temperature and furnace cooling. It was shown that the prediction can be extended to an 85 pct loss of property.

Precipitation Kinetics Analysis of the Cooling Process Following the Solid Solution Treatment of 7B50 Aluminum Alloy

Based on the TTP curves of 7050 alloy, and the continuous cooling curves of 7B50 alloy at different positions of Φ70 mm improved Jominy specimen, the hardness distribution along the thickness direction of 7B50 alloy thick plates was analyzed and predicted by means of the isothermal precipitation kinetics and the quench factor analysis method. The results show that when 7050 alloy is isothermal treated at 200°C~400°C, the exponent n in its Johnson-Mehl-Avrami equation is close to 1, which indicates that the nucleation process of new precipitates is stable. In this equation the coefficient k is 7.420E-03 at 350°C, which indicates that the nucleation and growth rates of new precipitates are very fast. The hardness distribution along the axial direction of the improved Jominy specimen of 7B50 alloy is predicted by the quench factor analysis method. When the distance is no more than 65 mm from the spraying surface of the improved Jominy specimen, the deviation between the predicted and measured hardness of 7B50 alloy in T6 temper is less than 5%. The quench factor analysis method is feasible to predict the hardness distribution along the thickness direction of 7B50 alloy thick plates after quenching and aging. When the quench factor analysis method is extended to predict the actual water spray quenching process of 7B50 alloy thick plates, the average cooling rate is 21.6°C/s in the quench sensitive temperature range of this alloy, at 15 mm from the spraying surface of the plate. At the same position, the corresponding quench factor is equal to 6 and the predicted hardness is 187.4 HV which is equivalent 98.5% of the Hmax (the maximum hardness) of 7B50 alloy in T6 temper.

Development of a partition panel of an Al6061 sheet metal part for the improvement of formability and mechanical properties by hot forming quenching

In this study, the hot forming quenching process was investigated to improve the deficiencies that arise in materials subjected to conventional cold stamping, such as low formability and undesirable mechanical properties. The hot forming quenching process was mainly discussed in terms of formability and mechanical properties in this study and was first evaluated by preliminary tests. To examine formability, an evaluation was conducted using hot-tensile and hemispherical-dome stretching tests at temperatures of 350°C and 450°C, respectively. In addition, the mechanical properties of the formed part were predicted using quench factor analysis, which was based on the cooling temperature during the die quenching process. These preliminary test results were then used to predict the formability and hardness of the partition panel of an automotive part, where the analytical results indicated high performance of the hot forming quenching process, in contrast to conventional forming. Finally, the hot forming quenching experiment of the partition panel was carried out to validate the predicted results and the obtained formability and hardness values were compared with conventional forming at room temperature using T4 and T6 heat-treated sheets. The analytical and experimental results indicate that the hot forming quenching process is a very effective method for obtaining desirable formability and mechanical properties in the forming of aluminum sheets.

Hardness Prediction of Tailor Rolled Blank in Hot Press Forming Using Quench Factor Analysis

This paper aims to predict the hardness of hot formed part for tailor rolled blank (TRB) by the FE-simulation coupled with quenching factor analysis (QFA). Dilatometry test of boron steel is performed at various range of cooling rates from 0.2 to 100°C/s using the dilatometer with forced air cooling system. The dilatometry test provides a hardness data according to cooling curves which are used to determine the material constants (K1~K5) of QFA and the time‒temperature‒property (TTP) diagram of boron steel. Then, FE‒simulation of hot press forming is conducted to predict the cooling curves of hot formed TRB part with a thickness combination of thicker 1.6mm and thinner 1.2mm which is called as rear side member of automotive component. The cooling curves of FE-simulation are applied to predict the hardness of hot formed rear side member using the QFA. Also, experiment of hot press forming is performed to verify the predicted results and to examine the effect of cooling curves on the hardness.

Ionization Quenching Factor measurement of 1 keV to 25 keV protons in Isobutane gas mixture

The French Institute for Radiation protection and Nuclear Safety (IRSN) is providing reference neutron fluence energy distribution at its standard monoenergetic neutron fields, produced at the AMANDE facility. The neutron energy is assessed by measuring the recoil nuclei energy in a μTPC detector, the LNE-IRSN/MIMAC detector. The knowledge of the ionization quenching factor (IQF) is fundamental to determine the kinetic energy of the recoil nuclei. For some various gases and pressures, discrepancies of about 15% were observed between IQF calculations using the SRIM software and experimental measurements. No data are available for the iC4H10 + 50% CHF3 gas mixture which are used for measurements from a few keV up to 565 keV neutron energies in the μTPC detector. The experimental determination of the IQF is of primary importance to provide reference neutron fluence energy distribution. After a short description of the experimental set-up, this paper presents the first results of the IQF measurements in a iC4H10 + 50% CHF3 gas mixture in the energy range 1 keV – 25 keV.

Hardness prediction of weldment in friction stir welding of AA6061 based on numerical approach

Abstract The purpose of study is to predict hardness of weldment in friction stir welding(FSW) process of AA6061 based on numerical approach. FE-simulation was performed to describe material behaviour in FSW process. In this study, bonding criteria, used in porthole die extrusion of aluminium alloy, was applied for FE-simulation of FSW. Mechanical properties of weldment were also predicted by quench factor analysis(QFA) considering volume fraction for untransformed during quenching. Experiment of FSW was preformed to verify prediction method by FE-simulation with bonding criteria and QFA. As a result, hardness of weldment in FSW process of AA6061 can be precisely predicted by the suggested method.

Applicability of the Peclet number approach to blow-off and flashback limits of common steelworks process gases

The ever-increasing importance of energy efficiency has given rise to numerous areas of concern for operators and developers of combustion plants; as the need to utilise fuel gases of increasingly poor quality and variability is essential for sustainability, while emission standards continuing to become more stringent. Swirl combustors are ubiquitous in industry owing to their great stability range which occurs due to the formation of a CRZ, which through the recycling of heat and active chemical species to the root of the flame enhances stability over a wide range of operating conditions.Alternative fuels containing hydrogen offer the possibility of reduced greenhouse gas emissions; however flashback is of special concern with hydrogen enriched fuels, owing to the very high flame speed of hydrogen. Many by-products of process and waste industries can include a high proportion of hydrogen, for example Coke Oven Gas. Alternatively, many by-product process gases can contain a high proportion of non-combustible species such as nitrogen and carbon dioxide which can substantially reduce their flame speed and as a consequence increase the possibility of the flame extinguishing through blow-off.This paper examines the blow-off and flashback potential of common steelworks process gases (including one which contains hydrogen) in a compact, premixed swirl burner in swirl number regimes representative of those found in practical systems. Methane is used as a base fuel for comparison. All results are obtained at atmospheric pressure without air preheat.The Peclet number modelling approach incorporating a flame quenching parameter was applied to the results obtained for each of the fuel gases. Using this model, the quench factor value was seen to be dependent on burner configuration as well as fuel composition.It was found that the stable burner operating conditions significantly change from fuel to fuel; with the operating points at which flashback occurs with Coke Oven Gas producing blow-off with weaker process gases such as Blast Furnace Gas and Basic Oxygen Steelmaking gas.

Manipulating fluorescence quenching efficiency of graphene by defect engineering

We report on the manipulation of the fluorescence quenching of Rhodamine 6G (R6G) on graphene by defect engineering via hydrogen and Ar+ plasma treatments. The amount and nature of defects in graphene were estimated on the basis of the Raman intensity ratios I(D)/I(G) and I(D)/I(D′) of graphene. Results showed that the quenching factor (QF) gradually decreases from ∼40 to ∼4 and ∼12 for hydrogenated graphene (sp3 defects) and Ar+-plasma-treated graphene (vacancy-like defects), respectively, with different amounts of defects. Our results indicated that the fluorescence quenching efficiency of graphene is strongly dependent on the amount and nature of defects.

Effects of Mg and Cu Content on Quench Sensitivity of Al–Si–Mg Alloy

Effects of Mg and Cu content on quench sensitivity of Al–Si–Mg-based cast alloys were investigated. Jominy end-quench test was performed to evaluate the quench sensitivity of Al–Si–Mg and Al–Si–Mg–Cu-based alloys. It was observed that the quench sensitivity of Al–Si–Mg alloy rises with the increase in Mg content. In general, quench factor values rise with the increase in distance away from the chill end of Jominy end-quench test bar. This is because the precipitation rate of strengthening particles increases with the increase in the concentration of quenched-in vacancy. The concentration of quenched-in vacancy declines with the decrease in cooling rate away from the chill end of test bar. The maximum quench factor value of Al–Si–0.57Mg alloy is 144.8, whereas those of Al–Si–0.35Mg and Al–Si–0.45Mg alloys are 38.5 and 34.8, respectively. This is in contrast to the quench factor values obtained in Al–Si–Mg alloy containing 0.8 %Cu. Results show that an addition of 0.8 % Cu to Al–Si–Mg alloy significantly reduces the quench sensitivity of the alloy. Quench factor values of Al–Si–Mg–0.8Cu alloy are in the range of 1–16. No significant reduction in the quench factor is observed on addition of 0.23 and 0.50 wt% of Cu to Al–Si–Mg alloy. Simulation results show that Guinier–Preston (GP) zones form in the Al matrix when the amount of Cu in the Al–Si–Mg alloy exceeds 0.57 wt% during the natural aging subsequent to quenching. These GP zones are well-known heterogeneous sites for nucleation of precipitates and are responsible for reducing quench sensitivity of the Al–Si–Mg–0.8Cu alloy.

Prediction of Hardness for Partially Quenched Boron Steel Using Quench Factor Analysis

The mechanical properties of hot stamped boron steel have been generally predicted by many empirical models based on the Kirkaldy's equation. Although predicting previous models are well-developed for prediction of mechanical properties, use of those models is still limitary in case of partial quenching process for tailored properties of component. Therefore, this study predicted the mechanical property of partially quenched boron steel by heated tools using the FE-simulation coupled with quench factor analysis (QFA). The dilatometry test of boron steel is performed at various ranges of cooling rates from 0.5 to 70℃ /s of which results are used to determine the material constants (K1~K8) of QFA and the time-temperature-property (TTP) diagram of boron steel. And then, FE-simulation of partial quenching is carried out to obtain the cooling curves according to heating temperatures of tool. The extracted results from FE-simulation are combined with the QFA to calculate the hardness distribution of partially quenched parts. Finally, experiment of partial quenching is performed to verify the predicted results and to examine the effect of tool temperatures on the hardness of formed part. The predicted hardnesses of U-channel parts are in good agreement with the measured ones within a maximum error of 7.4%.

Novel Method for Predicting Hardness Distribution of Hot-Stamped Part Using FE-Simulation Coupled with Quench Factor Analysis

In the hot stamping of boron-alloyed steel, the mechanical properties of hot-stamped parts have been predicted by many empirical models based on Kirkaldy’s equation. Although these models are skillfully developed, there is still a need to precisely and easily predict the mechanical properties in the hot stamping process. Therefore, this study aims to suggest a novel method for the accurate prediction of the hardness distribution of hot-stamped parts by the use of finite element (FE)-simulations coupled with quench factor analysis (QFA). First, dilatometry of boron steel was performed at various cooling rates from 0.5 to 70 K/s using a dilatometer with a forced-air cooling system. The dilatometry test provided hardness data according to the cooling rates, which were used to determine the material constants (K 1 to K 5) of the QFA and the time–temperature–property diagram of boron steel. Then, FE-simulation of hot stamping was conducted to obtain the cooling curves for blanks with thicknesses of 1.2 and 1.6 mm. The extracted results from the FE-simulation were used to predict the hardness distribution of the hot-stamped parts using QFA. Finally, a hot stamping experiment was performed to verify the predicted results and to examine the effect of the blank thickness on the cooling rates of a hot-stamped part. The predicted hardnesses for the parts were in good agreement with the measured values, within a maximum error of 4.96 pct.

A Numerical Approach to the Prediction of Hardness at Different Points of a Heat-Treated Steel

Accurate prediction of the mechanical properties in quenched steel parts has been considered by many recent researchers. For this purpose, different methods have been introduced. One of them is the quench factor analysis (QFA) which is based on continuous cooling rate during quenching. Another method for prediction of the mechanical properties in heat-treated alloys is artificial neural networks (ANNs). In the present research, QFA and ANN approaches have been used to predict the hardness of quenched steel parts in several different quench media. Then for the two methods, the predicted values have been compared with the experimental data. Results showed that the two methods are suitable in prediction of the hardness at different points of the quenched steel parts.

핫스템핑 공정에서 Quench Factor Analysis를 이용한 제품의 경도 예측

The purpose of the current study is to predict the hardness distribution in steel products after hot stamping using a quench factor analysis(QFA) coupled with FE-simulations. QFA is a method to predict properties such as hardness and tensile strength based on time-temperature-property(TTP) curves and can determine properties based on the temperature histories. The constants(K1~K5) of QFA were determined using hardness data obtained after various cooling rates. In the current study, a rear side member was selected for evaluation and FE-simulations were performed to obtain the temperature histories during hot stamping. The predicted temperature data were imported into the QFA to calculate the hardness distribution of the hot stamped parts. A hot stamping experiment of the rear side member was conducted to verify the predicted hardness. The simulation results show good agreement with the experimental measurements.

The Influence of Quenching and Aging on Fracture Toughness of the Al-Zn-Mg-Cu Alloy 7449

Abstract This investigation characterises the fracture toughness of the very high strength Aluminium alloy 7449. This Al-Zn-Mg-Cu alloy is heat treatable and relies on rapid quenching from the solution heat treatment temperature to promote subsequent artificial aging. While the influence of quench paths on strength is well understood and can be predicted using techniques like quench factor analysis, the influence of quench rate on fracture toughness is more challenging. The rate of quenching can influence the fracture toughness through complex precipitation reactions occurring during cooling. The precipitate locations dictate the magnitude of the detrimental effect on the fracture toughness. In this investigation, the fracture toughness of 7449 in two product forms was measured using compact tension specimens cut from forged blocks and rolled plate. These plane strain (KIC) results were also augmented with Charpy impact tests. Various quench conditions were investigated, including water at three different temperatures and poly oxyethylene glycol (PAG) in two concentrations. The influence of standard and novel aging procedures including retrogression and reaging was also determined. The combinations of strength and toughness have been related to the prevailing microstructural condition. Fracture toughness magnitudes were found to vary most significantly with rapidity of cooling from the solution treatment temperature, with the subsequent aging treatments having a much smaller effect.

Fluorescence enhancement and quenching of Eu(TTFA)3 by Ag nanoparticles at different excitations

The luminescence properties of Eu(TTFA)3 complex in presence of silver nanoparticles were investigated at three excitation wavelengths of 350nm, 383nm and 463nm, respectively. Luminescence quenching and enhancement were both observed at three different excitation and emission wavelengths. Luminescence at 612nm, 578nm, 590nm and 650nm were enhanced at excitation wavelength of 350nm, and quenched at excitation wavelength of 383nm. The enhancement factor reached to 1.6 and the quench factor was about 0.65. For 463nm excitation, the luminescence at 612nm was quenched, and the quench factor reached to 0.85. Luminescence at other three emission wavelengths (578nm, 590nm, and 650nm) was enhanced, with the greatest enhancement factor of ~5.

On the quench sensitivity of 7010 aluminum alloy forgings in the overaged condition

Abstract The quench sensitivity of an overaged 7010 alloy forging was characterized by tensile and Vickers hardness tests, as well as scanning electron microscopy. Longitudinal tensile specimens, excised from a rectilinear open die forging were cooled from the solution treatment temperature following thirty-two different cooling paths including interrupted and delayed quenches. SEM analysis of the microstructure showed that quench precipitates were (i) Al 2 CuMg (S) which nucleated heterogeneously on grain boundaries and (ii) Mg(Zn,Cu,Al) 2 (η) on grain boundaries, dispersoid bands, subgrain boundaries as well as in the aluminum matrix. The quench sensitivity of the alloy׳s yield strength and Vickers hardness was modeled simultaneously by quadruple-C curves, using an improved methodology for Quench Factor Analysis. The four C-curves used in the model represented loss of solute by (i) precipitation of S on grain boundaries, and precipitation of η (ii) on grain boundaries and dispersoid bands, (iii) on subgrain boundaries and (iv) in the matrix. The model yielded coefficient of determination ( R 2 ) values of 0.967 and 0.974 for yield strength and Vickers hardness, respectively. The model and the implications of the results are discussed in this paper.

Energy-dependent light quenching in CaWO $$_4$$ 4 crystals at mK temperatures

Scintillating CaWO $$_4$$ single crystals are a promising multi-element target for rare-event searches and are currently used in the direct dark matter experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers). The relative light output of different particle interactions in CaWO $$_4$$ is quantified by quenching factors (QFs). These are essential for an active background discrimination and the identification of a possible signal induced by weakly interacting massive particles (WIMPs). We present the first precise measurements of the QFs of O, Ca and W at mK temperatures by irradiating a cryogenic detector with a fast neutron beam. A clear energy dependence of the QF of O and, less pronounced, of Ca was observed for the first time. Furthermore, in CRESST neutron-calibration data a variation of the QFs among different CaWO $$_4$$ single crystals was found. For typical CRESST detectors the QFs in the region-of-interest (10–40 keV) are $$\hbox {QF}_\mathrm{O}^\mathrm{ROI}=(11.2\pm 0.5)$$ %, $$\hbox {QF}_\mathrm{Ca}^\mathrm{ROI}=(5.94\pm 0.49)$$ % and $$\hbox {QF}_\mathrm{W}^\mathrm{ROI}=(1.72\pm 0.21)$$ %. The latest CRESST data (run32) is reanalyzed using these fundamentally new results on light quenching in CaWO $$_4$$ having moderate influence on the WIMP analysis. Their relevance for future CRESST runs and for the clarification of previously published results of direct dark matter experiments is emphasised.

Isothermal Time-Temperature-Precipitation Diagram for an Aluminum Alloy 6005A by In Situ DSC Experiments.

Time-temperature-precipitation (TTP) diagrams deliver important material data, such as temperature and time ranges critical for precipitation during the quenching step of the age hardening procedure. Although the quenching step is continuous, isothermal TTP diagrams are often applied. Together with a so-called Quench Factor Analysis, they can be used to describe very different cooling paths. Typically, these diagrams are constructed based on mechanical properties or microstructures after an interrupted quenching, i.e., ex situ analyses. In recent years, an in situ calorimetric method to record continuous cooling precipitation diagrams of aluminum alloys has been developed to the application level by our group. This method has now been transferred to isothermal experiments, in which the whole heat treatment cycle was performed in a differential scanning calorimeter. The Al-Mg-Si-wrought alloy 6005A was investigated. Solution annealing at 540 °C and overcritical quenching to several temperatures between 450 °C and 250 °C were followed by isothermal soaking. Based on the heat flow curves during isothermal soaking, TTP diagrams were determined. An appropriate evaluation method has been developed. It was found that three different precipitation reactions in characteristic temperature intervals exist. Some of the low temperature reactions are not accessible in continuous cooling experiments and require isothermal studies.