Canale, Narazaki Journal of ASTM International Selected Technical Papers STP 1523 JAI • Quenching and Cooling, Residual Stress and Distortion Control Quenching and Cooling, Residual Stress and Distortion Control STP 1523 JAI Guest Editors: Lauralice de C.F Canale Michiharu Narazaki www.astm.org Photo courtesy of Inductoheat, Inc., An Inductotherm Group Company 4703 STP1523 Cover.indd ISBN: 978-0-8031-7509-9 Stock #: STP1523 8/18/10 12:36 PM Journal of ASTM International Selected Technical Papers STP1523 Quenching and Cooling, Residual Stress and Distortion Control JAI Guest Editors: Lauralice C.F Canale Michiharu Narazaki ASTM International 100 Barr Harbor Drive PO Box C700 West Conshohocken, PA 19428-2959 Printed in the U.S.A ASTM Stock #: STP1523 Library of Congress Cataloging-in-Publication Data Quenching and cooling, residual stress and distortion control / JAI guest editors, Lauralice C F Canale, Michiharu Narazaki p cm (Journal of ASTM International selected technical papers; STP1523) Includes bibliographical references and index ISBN: 978-0-8031-7509-9 (alk Paper) Steel Quenching Steel Defects I Canale, Lauralice de Campos Franceschini II Narazaki, Michiharu TN752.Q4Q456 2010 2010021122 672.3’6 dc22 Copyright © 2010 ASTM INTERNATIONAL, West Conshohocken, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Journal of ASTM International „JAI… Scope The JAI is a multi-disciplinary forum to serve the international scientific and engineering community through the timely publication of the results of original research and critical review articles in the physical and life sciences and engineering technologies These peer-reviewed papers cover diverse topics relevant to the science and research that establish the foundation for standards development within ASTM International Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use, or the internal, personal, or educational classroom use of specific clients, is granted by ASTM International provided that the appropriate fee is paid to ASTM International, 100 Barr Harbor Drive, P.O Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9634; online: http://www.astm.org/copyright The Society is not responsible, as a body, for the statements and opinions expressed in this publication ASTM International does not endorse any products represented in this publication Peer Review Policy Each paper published in this volume was evaluated by two peer reviewers and at least one editor The authors addressed all of the reviewers’ comments to the satisfaction of both the technical editor(s) and the ASTM International Committee on Publications The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of the peer reviewers In keeping with long-standing publication practices, ASTM International maintains the anonymity of the peer reviewers The ASTM International Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM International Citation of Papers When citing papers from this publication, the appropriate citation includes the paper authors, ⬘⬘paper title’’, J ASTM Intl., volume and number, Paper doi, ASTM International, West Conshohocken, PA, Paper, year listed in the footnote of the paper A citation is provided as a footnote on page one of each paper Cover image illustrates a dual-spindle induction heating and quenching of steel shafts Courtesy of Inductoheat Inc., An Inductotherm Group Company Printed in Bridgeport, NJ September, 2010 Foreword THIS COMPILATION OF THE JOURNAL OF ASTM INTERNATIONAL (JAI), STP1523 on Quenching and Cooling, Residual Stress and Distortion Control contains papers published in JAI highlighting the impact of the quenching process on the heat treatment of metals This STP is sponsored by ASTM Committee D-2 on Petroleum Products and Lubricants The JAI Guest Editors are Lauralice de C.F Canale, EESC Universidade de S:o Paulo, Brazil, and Michiharu Narazaki, Utsunomiya University, Utsunomiya, Japan Contents Overview ix Heat Transfer Experimental Technique for Heat Transfer Measurements on Fast Moving Sprayed Surfaces M Pohanka, H Bellerova, and M Raudensky Accurate Determination of Surface Heat Fluxes During Quenching Characterized by Boiling Water Heat Transfer M A Wells and K J Daun 16 Heat Transfer During Quenching and Assessment of Quench Severity—A Review K Narayan Prabhu and P Fernandes 40 Formulation of a Guideline for the Determination of Heat Transfer Coefficient during Gas Quenching T Luebben, M Lohrmann, S Segerberg, and P Sommer 63 Determination of Surface Heat Transfer Coefficients of Cr12MoV Steel Cylinder during High-Speed Gas Quenching at Atmospheric Pressure C Heming, L Jianyun, L Ziliang, H Lijun, and H Jie 84 Enhancement and Local Regulation of Metal Quenching Using Atomized Sprays U Alam, J Krol, E Specht, and J Schmidt 91 The Effect of Agitation and Quenchant Temperature on the Heat Transfer Coefficients for 6061 Aluminum Alloy Quenched in Distilled Water M Maniruzzaman, M Fontecchio, and R D Sisson, Jr 104 Modeling and Simulation A Review on Modeling and Simulation of Quenching C S ̦ ims ̦ ir and C H Gür 117 Modeling of Quenching and Tempering Induced Phase Transformations in Steels P T Rajeev, L Jin, T N Farris, and S Chandrasekar 157 Improving Control of a Quenching Process by Coupling Analysis Methods A Banka, J Franklin, Z Li, B L Ferguson, A Freborg, and M Aronov 186 Generalized Equation for Cooling Time Evaluation and Its Verification by CFD Analysis P Krukovskyi, N Kobasko, and D Yurchenko 205 Computer Simulation of Quenched Steel Working Stress B Smoljan, S Smokvina Hanza, and D Iljkic´ 228 A Novel Approach to Model Moving Heat Sources F D Fischer, C Krempaszky, J Ocˇenášek, and E Werner 245 Analysis of Stress Concentration around Inclusions due to Thermally Induced Strain to the Steel Matrix M R Allazadeh, C I Garcia, A J DeArdo, and M R Lovell 253 Considering the Body-Centered Cubic Lattice Parameter of ␣-Fe Alloys versus Concentrations of Solved Elements V P Filippova 269 Application of thermodynamics and kinetics in the designing of new type TRIP steels concerning Al and P effects L Li, S G Huang, L Wang, Y L He, J Vleugels, and O Van der Biest 284 Model of Solid State Transformations of Ductile Cast Iron GJS-600 V Runser and V Schulze 295 Distortion and Residual Stresses Using Polyalkylene Glycol Quenchants to Effectively Control Distortion and Residual Stresses in Heat Treated Aluminum Alloys T Croucher 309 Minimizing Machining Distortion in Aluminum Alloys through Successful Application of Uphill Quenching—A Process Overview T Croucher 332 Explanation of the Origin of Distortion and Residual Stress in Carburized Ring Using Computer Simulation K Arimoto, S Yamanaka, and K Funatani 352 The Analysis and Control of Distortion in Carbonitrided and Nitrocarburized ThinShelled Plain Carbon Steel Automotive Powertrain Components V Campagna, D O Northwood, R Bowers, X Sun, and P Bauerle 364 The Effect of Core and Carburized Surface Microstructural Stability on Residual Stress Evolution during Tempering J Vatavuk, M Zicari di Monte, and A A Couto 387 Explanation on the Origin of Distortion in Induction Hardened Ring Specimens by Computer Simulation T Horino, F Ikuta, K Arimoto, C Jin, and S Tamura 398 Optimum Strategies to Reduce Residual Stresses and Distortion during the Metal Quenching Process A K Nallathambi, Y Kaymak, E Specht, and A Bertram 411 Numerical Simulation of Residual Stresses in Quenched Steel Bodies Using Subroutines to Represent TTT and CCT Diagrams E M Bortoleto, C F Lagatta, M G Di Vernieri Cuppari, I F Machado, and R Martins de Souza 436 Prediction of Distortion of Automotive Pinion Gears during Quenching Using CFD and FEA D S MacKenzie, A Kumar, H Metwally, S Paingankar, Z Li, and B L Ferguson 450 Property Predictions Prediction of Quench-Hardness within the Whole Volume of Axially Symmetric Workpieces of Any Shape B Lišcˇic´, S Singer, and B Smoljan 467 Correlation between Thermal and Mechanical Properties of the 10NiCr11 T Ghrib, M Bouhafs, and N Yacoubi 489 An Efficient Numerical Algorithm for the Prediction of Thermal and Microstructure Fields during Quenching of Steel Rods S K Ali, M S Hamed, and M F Lightstone 500 Quenchants and Quenching Starch-Based Quenchants as an Eco-Friendly Alternative to Quenching Oil S S Sahay 525 Comparison of Structure and Quenching Performance of Vegetable Oils E C de Souza, M R Fernandes, S C M Augustinho, L de Campos Franceschini Canale, and G E Totten 531 Severity of Quenching and Kinetics of Wetting of Nanofluids and Vegetable Oils V Jagannath and K N Prabhu 571 An Investigation on Quenching Performance of Hot Alkaline Bath S Raygan, J Rassizadehghani, and M Askari 584 A Feasibility Study of the Use of Bismuth Bath to Replace Lead Bath as the Quenching Media for Steel Heat-Treating J Ru and Z Wang 596 Spray Quenching in Induction Hardening Applications V Rudnev 609 Technology and Applications of Alternately Timed Quenching Technology N Chen, X Zuo, S Zhou, and J Xu One More Discussion “What is Intensive Quenching Process?” N I Kobasko, M A Aronov, J A Powell, and G E Totten 622 629 Energy Efficient and Eco-friendly Intensively Quenched Limited Hardenability Low Alloy Steels N I Kobasko 644 An Overview of Technology and Equipment for Hardening of Large Steel Parts L N Deyneko, N I Kobasko, V V Dobryvechir, and E I Litvinenko 662 Accelerated Cooling of Steel Plates: The Time Has Come A A Gorni and J H D da Silveira 682 Overview of Pearlitic Rail Steel: Accelerated Cooling, Quenching, Microstructure, and Mechanical Properties S S Sahay, G Mohapatra, and G E Totten 692 Water and Polymer Quenching of Aluminum Alloys: A Review of the Effect of Surface Condition, Water Temperature, and Polymer Quenchant Concentration on the Yield Strength of 7075-T6 Aluminum Plate G S Sarmiento, C Bronzini, A C Canale, L C F Canale, and G E Totten 728 757 Gas Quenching Gas-Jet Quenching P Stratton Quenching Homogeneity and Intensity Improvement in Batch Mode High Pressure Gas Quenching R.-R Schmidt and U Fritsching 776 Gas-Cooling of Multiple Short Inline Disks in Flow Along Their Axis N Lior and D Papadopoulos 795 Numerical Simulation of the Mechanical Properties of Cr12 Steel during Gas Quenching Z Li, H Cheng, J Li, and L Hou 820 Hardenability Enhanced Hardenability through Application of Magnetic Fields I F Machado A New Method to Study the Effect of Cooling Rate on the Decomposition of Austenite in Advanced High Strength Sheet Steels K Cho, C I Garcia, M Hua, J Lee, Y S Ahn, and A J DeArdo 833 843 Cooling Curve Analysis Methodologies Quenchant Characterization by Cooling Curve Analysis L C F Canale, X Luo, X Yao, and G E Totten 861 Cooling Characteristic Test of Quenching Media G.-y Zeng 900 A Complete System for Testing and Evaluation of Quenchants and Quenching Systems H Kristoffersen, E Troell, I Felde, and J Bodin 914 Effects of Cooling Rate Fluctuation on Cooling and Transformation Behavior of Steel upon Direct Quenching X Luo and J Li 935 Correlation between Cooling Curves Obtained with a Silver Probe and Quenching Properties of 5140 Steel Bars R S Wang, Y Wang, and L P Su 953 Measurement of the Cooling Power of Polyethylene Glycol Aqueous Solutions Used as Quenching Media R Ikkene, Z Koudil, and M Mouzali 977 991 Analysis of the Segerberg Hardening Power Equation C Chun-huai and Z Jing-en 1021 Evolution of Quench Factor Analysis: A Review P M Kavalco and L C F Canale The Influence of Surface Temperature on Rewetting Behavior During Immersion Quenching of Hollow and Solid Cylinders F Frerichs and Th Luebben 1032 Dilatometric Analysis Dilatometric Analysis to Study Aging of Aluminum Alloys R Gerosa, B Rivolta, and U Derudi 1055 Optimization of the Heat Treatment of a 17-4 PH Stainless Steel by Dilatometric Technique R Gerosa, B Rivolta, and A Sala 1066 1077 Subject Index 1081 Author Index Overview Quenching and distortion control continue to be of great concern to the metals processing industry since they exhibit tremendous effects on quality and profitability Recently, many papers on topics directly and indirectly related to quenching and quenching processes have been published in the Journal of ASTM International (JAI) In view of the interest and importance of these topics to the thermal processing industry, a total of 59 JAI papers have been collected together into this ASTM Special Technical Publication (STP) and these papers have been organized into nine topical sections: Heat Transfer; Modeling and Simulation; Distortion and Residual Stresses; Property Predictions; Quenchants and Quenching; Gas Quenching; Hardenability; Cooling Curve Analysis Methodologies; and Dilatometric Analysis The Heat Transfer section includes papers describing experimental techniques for measurements of heat transfer distribution at the spray cooled surface and in gas quenching systems Also included are mathematical models to promote accurate characterization of heat transfer throughout the quenching operation There are also papers which review the characteristics of various quench media, effects of process parameters on quenching, mechanisms of thermal transport, and techniques for the estimation of heat transfer coefficients Heat transfer studies for atomized water sprays, liquid media, and gas quenching system are discussed Modeling and Simulation are powerful tools in the design, optimization, and understanding of the quenching process and they are used increasingly in component manufacture The development of simulation tools for quenching is critical for improving process performance by minimizing distortion and maximizing service life Therefore, this section describes several examples utilizing FEM (Finite Element Methods), a combination of methods such as CFD (Computational Fluid Dynamics) and FEM-based thermal process models, to provide efficient and effective solutions applicable to quenching and tempering processes Solid state transformations of ductile iron and new design steels are also discussed One section is focused on Distortion and Residual Stresses Benefits associated with polymer quenching and uphill quenching for aluminum alloys are discussed Carbonitriding and nitrocarburizing processes and their relationship with respect to size and shape distortion, retained austenite, and residual stresses are also discussed Papers discussing tempering effects on as-quenched compressive residual stresses of carburized steel and the application of commercial codes including FLUENT, DANTE, CFD, ABAQUS, and Fortran subroutines to model and analyze residual strain, internal ix Reprinted from JAI, Vol 5, No doi:10.1520/JAI101779 Available online at www.astm.org/JAI R Gerosa,1 B Rivolta,1 and A Sala2 Optimization of the Heat Treatment of a 17-4 PH Stainless Steel by Dilatometric Technique ABSTRACT: The precipitation-hardening steels are generally required when high mechanical performances at high temperatures are requested both statically and dynamically The requested combination of mechanical strength and toughness is achieved by means of an age-hardening treatment which can be carried out at different temperatures and times Aging 17-4 PH 共precipitation-hardening兲 in the temperature range of 480–620°C results in a precipitation hardening due to the formation of a submicroscopic, copper-rich phase In the technical literature, the investigation of the phase transformation and the age-hardening behavior of the steel has been carried out at different stages of aging by different techniques, such as transmission electron microscopy studies and x-ray diffraction of the precipitates together with optical and scanning electron microscope analysis of the microstructure In this paper an alternative method based on dilatometric experiments is proposed to study the kinetics of the age hardening of the steel The experiments have been carried out at different temperatures on quenched samples and the transformation of the structure during aging has been continuously followed up to h For a better investigation of the data obtained from the Manuscript received April 14, 2008; accepted for publication July 14, 2008; published online September 2008 Dept of Mechanics, Politecnico di Milano, Milano 20156, Italy Student of MSc in Mechanical Engineering, Politecnico di Milano, Polo Regionale di Lecco, Milano 2056, Italy He developed his Master’s thesis about this subject but he did not succeed in discussing his thesis and graduate due to an accident in the Como Mountains in which he lost his life a month before the discussion We worked with him very well and we found his work, complete, on his laptop With the support of his family we decided to take it, summarize it, and submit it for an international publication It is a method to remember him and to fix his name and his work in the technical literature of Metallurgy which he loved so much…while he is still walking in his beloved mountains Cite as: Gerosa, R., Rivolta, B and Sala, A., ‘‘Optimization of the Heat Treatment of a 17-4 PH Stainless Steel by Dilatometric Technique,’’ J ASTM Intl., Vol 5, No doi:10.1520/JAI101779 Copyright © 2008 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 1066 GEROSA ET AL., doi:10.1520/JAI101779 1067 dilatometric analysis, mechanical tests, notch impact tests, and microstructural analysis have been carried out at different and selected parameters of the aging Introduction The 17-4 PH 共precipitation-hardening兲 stainless steel is a martensitic stainless steel containing approximately wt % Cu and is strengthened by the precipitation of highly dispersed copper particles in the martensite matrix 关1,2兴 Precipitation-hardened stainless steels were developed during the 1940s, and since then, they have become increasingly important in a variety of applications in which their special properties can be used The most important of these properties are ease of fabrication, high strength, relatively good ductility, and excellent corrosion resistance This alloy is more common than any other type of precipitation-hardened stainless steel and has been used for a wide variety of applications, including chemical process equipments, fasteners, nuclear reactor components, gears, and steam turbine parts After solution treatment and cooling to room temperature, 17-4 PH stainless steel exhibits a Martensitic structure but does not exhibit high hardness 关3兴 The aging in the temperature range of 480– 620 ° C produces a precipitation hardening of the steel due to the formation of a submicroscopic copper-rich phase It is well known in the technical literature that in the early stage of the precipitation of copper, coherent body-centered-cubic 共bcc兲 clusters nucleate and grow in the supersaturated bcc matrix and progressively lose coherency after reaching a certain critical size 关4–7兴 The evolution of the microstructure during the aging time and varying the aging temperature has been extensively studied both through traditional and sophisticated techniques, such as the x-ray diffraction, scanning electron microscope 共SEM兲 and transmission electron microscope analysis All these studies clarify that the age hardening involves initial formation of coherent copper-rich clusters that became incoherent face-centered-cubic 共fcc兲 copper precipitates upon further aging In general, the maximum strength and hardness values can be obtained after initially aging at 450– 510 ° C, during which the precipitation of coherent copper-rich clusters occurs 关1,2兴 Aging at a temperature above 540 ° C results in the precipitation of incoherent fcc copper-rich precipitates, lower strength and hardness, and enhanced toughness 关1,2兴 At higher aging temperatures, around 570 ° C and above, formation of reversed austenite phase is observed 关3,4,7兴 It is noted that the reversed austenite formed notwithstanding the aging temperature being much lower than the Ac1 temperature This phenomenon is well known in the technical literature and can be understood as follows It has been observed that copper particles precipitate before austenite formed, so that the subsequent austenite formation took place in a matrix containing finely dispersed copper particles Copper particles are expected to be a favorable nucleation site for reversed austenite 共although there is no one-to-one correspondence兲, since both copper and austenite have the same fcc structure with a similar lattice parameter During prolonged aging at the higher temperature 1068 JAI • STP 1523 ON QUENCHING TABLE 1—Chemical composition of 17-4 PH steel used in the investigation C 0.04 Si 0.41 S 0.004 P 0.02 Mn 0.41 Cr 15.40 Ni 4.31 Nb+ Ta 0.26 Cu 3.24 N 共ppm兲 410 共620 ° C兲, it is presumed that the diffusion of copper, nickel, and iron atoms would have a deep influence on the precipitates and the matrix, and lead to austenite forming element enriched areas around the copper precipitates, which could trigger reversed austenite to nucleate Furthermore, the growth of reversed austenite attracted considerable amounts of copper and nickel from the martensite matrix as the solubility of these elements in austenite is much higher In this paper an alternative method based on dilatometric experiments is proposed to study the kinetics of the age hardening of the steel The experiments have been carried out at different temperatures on quenched samples and the transformation of the structure during aging has been continuously followed up to h The obtained data have been related to the hardness values and mechanical tests, notch impact tests, and microstructural analysis have been carried out at different and selected parameters of the aging Materials and Methods The chemical composition in wt % of the 17-4 PH stainless steel used in this investigation is reported in Table The material was in the form of 33.5 in forged blades from a low pressure steam turbine Prisms of 25 mm⫻ 12 mm⫻ 120 mm were machined from the blades, each specimen was solution treated at 1040 ° C for 30 and then air cooled to room temperature Prisms of mm⫻ mm⫻ 40 mm were machined for the aging tests, performed in a vitreous push-rod model Netzsch 402ES dilatometer The aging treatments were performed at different temperatures in the range 450– 625 ° C, i.e., 450, 475, 530, 570, 600, and 625° C, for periods of time up to h The change of dimensions of each specimen was measured and recorded continuously during the aging For a better understanding of the aging reactions, hardness measurements were carried out on specimens aged in a laboratory furnace at the same temperatures investigated by the dilatometer for periods of time ranging from 0.5 to h The hardness measurements were taken using a Vickers hardness tester with a load of kg By analysis of both the dilatometric and hardness curves, the activation energy associated with the precipitation phenomenon was calculated In order to investigate the effect of overaging, tensile and impact tests were performed on specimens aged in a laboratory furnace at different times for each investigated temperature GEROSA ET AL., doi:10.1520/JAI101779 1069 FIG 1—Dimensional change ⌬L/Lo and Vickers hardness versus aging time at different aging temperatures Results and Discussion The critical temperatures have been detected by a push-rod vitreous dilatometer 共Netzsch model 402 ES兲 and the results are Ac1 = 650 ° C and Ac3 = 690 ° C, obtained with K / heating rate After solution treatment at 1040 ° C for 30 min, aging treatments have been performed in the dilatometer at different temperatures and the obtained results are reported in Fig for each aging temperature The dimensional change is defined as ⌬L Lf − L0 = L0 L0 where: Lf ⫽ length of the sample and L0 ⫽ length at the beginning of the test, at 20 ° C 共1兲 1070 JAI • STP 1523 ON QUENCHING From the analysis of the obtained results, the following considerations should be noted: 共1兲 The aging of the 17-4PH steel is always associated with a shrinkage of the sample, occurring during the aging 共2兲 The shrinkage rate varies by varying the temperature and time of the aging 共3兲 The higher hardness rates are associated with the higher shrinkage rates of the sample 共4兲 At 450 and 475 ° C aging temperatures, the dilatometric curve is characterized by high shrinkage rates at the first time which corresponds to high hardness increase rates and after 100 is characterized by a steady state both in the hardness and dimensional change profile 共5兲 At 530, 570, 600, and 625 ° C aging temperatures, the dilatometric curves are not able to record the precipitation phenomena giving rise to the hardness peak and taking place during the heating of the sample 共6兲 The time corresponding to the hardness peak is placed at shorter values when increasing the aging temperature 共7兲 The dilatometric curves at 600 and 625 ° C show a continuous shrinkage of the sample, associated with a continuous decreasing in the hardness, arriving at values even lower than the one of the as-quenched condition From the hardness curves it is possible to calculate the activation energy associated with the precipitation phenomena, according to v = Ce−Q/RT 共2兲 where: v Q R T ⫽ ⫽ ⫽ ⫽ reaction rate, activation energy, gas universal constant, and absolute temperature The same approach has been used to calculate the activation energy of the precipitation phenomena from the dilatometric curves The calculations have been carried out on the dilatometric curves at 450 and 470 ° C because they are the only ones able to follow the precipitation phenomenon giving rise to the peak hardening of the steel The reaction rate has been calculated with two methods, using both the hardness approach and the dilatometric curves approach, as follows: v = d共HV兲 / dt for the hardness curves and v = d共⌬L / Lo兲 / dt for the dilatometric curves The obtained results are reported in Table 2: The obtained values perfectly agree with the technical literature 关5兴 and are very close to each other Thus, it can be concluded that the two approaches can be considered equally able to describe the precipitation-hardening phenomena occurring in the metal GEROSA ET AL., doi:10.1520/JAI101779 1071 TABLE 2—Calculated values of the activation energy with the two approaches Activation Energy 共kJ/mol兲 81 87 Approach Hardness curves Dilatometric curves The time corresponding to the hardness peak by varying the aging temperature has been plotted in function of the inverse value of the absolute temperature, as shown in Fig It is evident from Fig that the coupled time–temperature giving rise to the peak hardness can be well described by T共log t + 6.9兲 = 5039 共3兲 where: T ⫽ aging temperature 共K兲 and t ⫽ aging time 共h兲 This means that if the aging temperature is increased, the time of the peak hardening will decrease, according to Eq The peak hardness aging parameters can be well described by the hardness approach, while the isothermal dilatometric curves are not able to describe the phenomenon completely, especially at temperatures equal and higher than 530 ° C, because it is too fast to be followed by isothermal dilatometric treatment In order to clarify the influence of the aging soaking time, tensile tests have been carried out on specimens aged at different times, according to Table For all the aging temperatures an overaging of 300 has been investigated and for each temperature different aging times produced a hardness value after the peak hardening equal to the one produced by the FIG 2—Peak hardness time versus temperature 1072 JAI • STP 1523 ON QUENCHING TABLE 3—Parameters of the aging used for the tensile and impact tests Aging Temperature 共°C兲 450 475 530 570 600 625 Aging Time 共min兲 75 300 75 300 150 300 150 300 100 300 60 300 Material Code 450 A 共aged兲 450 OA 共overaged兲 475 A 475 OA 530 A 530 OA 570 A 570 OA 600 A 600 OA 625 A 625 OA 300 aging The aim is to investigate the effect of the overaging on the tensile strengths and impact test values at equal hardness values The obtained results from the tensile tests are reported in Fig The obtained results show that 共1兲 The influence of the overaging can be considered trifling for the aging at 450 and 475 ° C and the data agree well with those obtained both from the hardness tests and from the dilatometric tests, which show a steady state condition after the peak hardening 共2兲 The influence of the overaging is more pronounced on the yield stress for the aging at temperatures higher than 530 ° C, and especially at 625 ° C At this temperature, the influence of the overaging on the hardness is trifling, while the shrinkage tends to continuously grow with the aging time This phenomenon can be explained if considering the wellknown formation of reversed austenite 关3,4,7兴 taking place at aging temperature higher than 570 ° C A complete microstructural investigation has been carried out by light optical microscope and by scanning electron microscope FIG 3—Yield stress and ultimate stress values at different aging temperatures and time GEROSA ET AL., doi:10.1520/JAI101779 1073 FIG 4—Light optical microscope micrograph of the 625 °C OA sample FIG 5—SEM micrograph of the 600 °C OA sample 1074 JAI • STP 1523 ON QUENCHING FIG 6—FATT values in the overaged condition In all the examined cases, the observed microstructure is martensite, as shown with some examples, in Figs and For a complete investigation, impact tests have been carried out at different temperatures in order to characterize the behavior of the material and the fracture appearance transition temperature 共FATT兲 values have been found 共Fig 6兲 For the agings carried out at 600 and 625 ° C, the FATT values are lower than −100 ° C and the samples show a fracture surface that is completely ductile For the aging temperatures having the highest mechanical characteristics 共i.e., 450, 475, 530, and 570 ° C兲, further analyses have been carried out and the FATT values in the aged condition have been reported in Fig FIG 7—FATT values in the aged conditions GEROSA ET AL., doi:10.1520/JAI101779 1075 Concluding Remarks In this experimental work, the dilatometric technique has been applied in studying the precipitation kinetics of the copper-rich phase occuring during aging of a 17-4 PH stainless steel The obtained results show that: 共1兲 The aging of the 17-4PH steel is always associated with a shrinkage of the sample versus aging time, and the shrinkage rate varies by varying the temperature and time of the aging 共2兲 The higher shrinkage rates of the sample are associated with the higher hardness rates 共3兲 The activation energy of the precipitation phenomena has been calculated from the dilatometric curves as well from the hardness curves and the data agree well with the technical literature 共4兲 The peak hardness aging parameters can be well described by the hardness approach, while the isothermal dilatometric curves are not able to describe the phenomenon completely, especially at temperatures equal to and higher than 530 ° C, because it is too fast to be followed by isothermal dilatometric treatment 共5兲 The influence of the overaging is more pronounced on the yield stress and on the FATT values for the aging at temperatures higher than 530 ° C, and especially at 625 ° C At this temperature, the influence of the overaging on the hardness is trifling, while the phenomenon is shown in the dilatometric curves, where the shrinkage tends to continuously grow with the aging time This phenomenon can be explained if considering the well-known formation of reversed austenite taking place at aging temperature higher than 570 ° C 关8,9兴 References 关1兴 关2兴 关3兴 关4兴 关5兴 关6兴 关7兴 Martin, J W., Precipitation Hardening, 2nd ed., Butterworth-Heinemann, London, 1998 “Metallic Materials Properties Development and Standardization 共MMPDS兲,” Office of Aviation Research, Washington, D.C 20591, January 2003 Hsiao, C N., Chiou, C S., and Yang, J R., “Aging Reactions in a 17-4 PH Stainless Steel,” Materials Chemistry and Physics, Vol 74, No 2, 2002, pp 134–142 El Hilali, F., Habashi, M., and Mohsine, A., “Comportement Mecanique de l’Acier Inoxydable Martensitique 17-4 PH en Corrosion sous Contrainte et a la Fragilisation par l’Hydrogene environnemental,” Annales de Chimie 共Paris兲, Vol 24, No 3, 1999, pp 169–194 Faccoli, M., Ghidini, A., and Roberti, R., “A Study of the Strengthening Mechanism in the Novel Precipitation Hardening Keylos®2001 steel,” Proceedings of the Seventh International Tooling Conference, Vol 2, Politecnico di Torino, May 2–5, 2006, pp 153–161 Garcìa de Andrés, C., Caballero, F G., Capdevila, C., and Álvarez, L F., “Application of Dilatometric Analysis to the Study of Solid-Solid Phase Transformations in Steels,” Materials Characterization, Vol 48, No 1, 2002 pp 101–111 Frigeni, A., Gerosa, R., Rivolta, B., and Derudi, U., “Il Dilatometro per Seguire 1076 JAI • STP 1523 ON QUENCHING 关8兴 关9兴 l’Invecchiamento delle Leghe Leggere,” 18th Convegno Nazionale Trattamenti Termici AIM, June 12–14, 2001, pp 437–446 Derudim, U., Rivolta, B., Meles, G., and Silvestri, A., “Cinetica di Precipitazione e Caratteristiche Meccaniche a Caldo di Leghe di Alluminio Aggiunta di 5% di Rame,” 29th Convegno Nazionale AIM, November 13–15, 2002 Hsiao, C N., Chiou, C S., and Yang, J R., “Aging Reactions in a 17-4 PH Stainless Steel,” Materials Chemistry and Physics, Vol 74, 2002, pp 134–142 1077 Author Index A Ahn, Y S., 843-858 Alam, U., 91-103 Ali, S K., 500-522 Allazadeh, M R., 253-268 Arimoto, K., 398-410, 352-363 Aronov, M., 186-204, 629-11 Askari, M., 584-595 Augustinho, S C M., 531-570 B Banka, A., 186-204 Bauerle, P., 364-17 Bellerova, H., 3-15 Bertram, A., 411-435 Bodin, J., 914-934 Bortoleto, E M., 436-449 Bouhafs, M., 489-499 Bowers, R., 364-17 Bronzini, C., 728-18 C Campagna, V., 364-17 Canale, A C., 728-18 Canale, L C F., 991-1018, 861-899, 728-18 Chandrasekar, S., 157-185 Chen, N., 622-628 Cheng, H., 820-829 Cho, K., 843-858 Chun-huai, C., 1021-1031 Couto, A A., 387-397 Croucher, T., 309-331, 332-351 D Daun, K J., 16-39 de Campos Franceschini Canale, L., 531-570 de Souza, E C., 531-570 de Souza, R M., 436-449 DeArdo, A J., 843-858, 253-268 Derudi, U., 1055-1065 Deyneko, L N., 662-681 di Monte, M Z., 387-397 Di Vernieri Cuppari, M G., 436-449 Dobryvechir, V V., 662-681 Dolabela da Silveira, J H., 682-691 F Farris, T N., 157-185 Felde, I., 914-934 Ferguson, B L., 186-204, 450-463 Fernandes, M R., 531-570 Fernandes, P., 40-62 Filippova, V P., 269-283 Fischer, F D., 245-6 Fontecchio, M., 104-114 Franklin, J., 186-204 Freborg, A., 186-204 Frerichs, F., 1032-1051 Fritsching, U., 776-794 Funatani, K., 352-363 G Gür, C H., 117-156 Garcia, C I., 843-858, 253-268 Gerosa, R., 1066-1076, 1055-1065 Ghrib, T., 489-499 Gorni, A A., 682-691 H Hamed, M S., 500-522 He, Y L., 284-294 Heming, C., 84-90 Horino, T., 398-410 Hou, L., 820-829 Hua, M., 843-858 Huang, S G., 284-294 1078 I Ikkene, R., 977-990 Ikuta, F., 398-410 Iljkic´, D., 228-244 J Jagannath, V., 571-583 Jianyun, L., 84-90 Jie, H., 84-90 Jin, C., 398-410 Jin, L., 157-185 Jing-en, Z., 1021-1031 K Kavalco, P M., 991-1018 Kaymak, Y., 411-435 Kobasko, N., 205-227 Kobasko, N I., 644-661, 662-681, 629-11 Koudil, Z., 977-990 Krempaszky, C., 245-6 Kristoffersen, H., 914-934 Krol, J., 91-103 Krukovskyi, P., 205-227 Kumar, A., 450-463 L Lagatta, C F., 436-449 Lee, J., 843-858 Liš~ic´, B., 467-488 Li, J., 820-829, 935-952 Li, L., 284-294 Li, Z., 820-829, 186-204, 450-463 Lightstone, M F., 500-522 Lijun, H., 84-90 Lior, N., 795-819 Litvinenko, E I., 662-681 Lohrmann, M., 63-83 Lovell, M R., 253-268 Luebben, T., 63-83, 1032-1051 Luo, X., 861-899, 935-952 M Machado, I F., 436-449, 833-842 MacKenzie, D S., 450-463 Maniruzzaman, M., 104-114 Metwally, H., 450-463 Mohapatra, G., 692-727 Mouzali, M., 977-990 N Nallathambi, A K., 411-435 Northwood, D O., 364-17 O O~enášek, J., 245-6 P Paingankar, S., 450-463 Papadopoulos, D., 795-819 Pohanka, M., 3-15 Powell, J A., 629-11 Prabhu, K N., 571-583, 40-62 R Rajeev, P T., 157-185 Rassizadehghani, J., 584-595 Raudensky, M., 3-15 Raygan, S., 584-595 Rivolta, B., 1066-1076, 1055-1065 Ru, J., 596-10 Rudnev, V., 609-9 Runser, V., 295-306 S Sahay, S S., 692-727, 525-530 Sala, A., 1066-1076 Sarmiento, G S., 728-18 Schmidt, J., 91-103 Schmidt, R.-R., 776-794 Schulze, V., 295-306 Segerberg, S., 63-83 S ̦ ims ̦ir, C., 117-156 1079 Singer, S., 467-488 Sisson, R D., 104-114 Smokvina Hanza, S., 228-244 Smoljan, B., 467-488, 228-244 Sommer, P., 63-83 Specht, E., 91-103, 411-435 Stratton, P., 757-775 Su, L P., 953-976 Sun, X., 364-17 T Tamura, S., 398-410 Totten, G E., 692-727, 861-899, 531-570, 728-18, 629-11 Troell, E., 914-934 W Wang, L., 284-294 Wang, R S., 953-976 Wang, Y., 953-976 Wang, Z., 596-10 Wells, M A., 16-39 Werner, E., 245-6 X Xu, J., 622-628 Y Yacoubi, N., 489-499 Yamanaka, S., 352-363 Yao, X., 861-899 Yurchenko, D., 205-227 Z V Van der Biest, O., 284-294 Vatavuk, J., 387-397 Vleugels, J., 284-294 Zeng, G.-y., 900-913 Zhou, S., 622-628 Ziliang, L., 84-90 Zuo, X., 622-628