Skip Nav Destination
Close Modal
Update search
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
NARROW
Format
Topics
Subjects
Article Type
Volume Subject Area
Date
Availability
1-14 of 14
Aging
Close
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
Sort by
Proceedings Papers
IFHTSE2024, IFHTSE 2024: Proceedings of the 29th International Federation for Heat Treatment and Surface Engineering World Congress, 50-56, September 30–October 3, 2024,
Abstract
View Paper
PDF
Effective heat treatment is essential for optimizing the properties of steels in various applications. Understanding the evolution of steel microstructure during intrinsic or post-heat treatment, along with managing distortions and residual stresses, is crucial for ensuring component usability. In laser-based additive manufacturing, high temperature gradients and cooling rates induce residual stresses, impacting the heat-affected zones. However, there remains a gap in understanding how stress influences precipitation during heat treatment, particularly regarding transformation-induced plasticity (TRIP), where a stress triggers deformation during phase transformation. This study aims to investigate TRIP effects during the aging of maraging steels, commonly employed in laser-based powder bed fusion. During the experiments, the steels were continuously aged under varying compression stresses. By isolating TRIP strain from total strain, the study establishes a relationship between maximum TRIP strain after phase transformation and applied stress, defining specific TRIP constants for each steel. The presence of TRIP strain has been confirmed during short time continuous aging treatments, indicating its significance even in the initial stages of the heat treatment process. While the applied stress level does not affect hardness, significant differences in maximum hardness values after aging were observed among the investigated materials. Furthermore, a comparative analysis of different maraging steels revealed a positive correlation between the TRIP constant and the amount of precipitation, and consequently, hardness. These findings confirm the role of TRIP in precipitate formation in maraging steels and provide a foundation for further understanding and predicting post-heat treatment material states.
Proceedings Papers
IFHTSE2024, IFHTSE 2024: Proceedings of the 29th International Federation for Heat Treatment and Surface Engineering World Congress, 167-172, September 30–October 3, 2024,
Abstract
View Paper
PDF
Additively manufactured (AM) metals require a modified heat treatment to accommodate for slight differences in composition caused by powder atomization and cover gas used in the manufacturing process. 17-4PH stainless steel (17-4PH) is a precipitation hardening steel which hardens through the formation of Cu precipitates in a martensitic matrix during aging treatment. The powders used in Laser Powder Bed Fusion (LPBF) fabrication of 17-4PH are typically spray atomized using N 2 cover gas, which is associated with a certain amount of nitrogen uptake. Nitrogen is a potent austenite stabilizer and will lower the martensite start temperature of the steel. To counteract the effect of nitrogen, a sub-zero heat treatment can be introduced to promote a more complete transformation into martensite. In this work, the effect of nitrogen on the heat treatment response of 17-4PH is investigated through comparing standard wrought, nitrogen loaded wrought, and LPBF 17-4PH. In particular, the effect of introducing a subzero treatment is addressed. After quenching from the solutionizing step (austenitization) LPBF fabricated 17-4PH was cold-treated in different combinations of dry ice (-78 °C) and boiling nitrogen (-196 °C). Subsequently, these conditions were aged in the conventional way. The sub-zero treatments were compared with the conventional heat treatment procedure, which does not entail a sub-zero step. In addition, phase transformations (above room temperature) were monitored in-situ using dilatometry. Finally, hardness tests and XRD analysis were performed to characterize the final microstructure. It is demonstrated that sub-zero treatment can be an effective route to address the problems associated with the additional nitrogen present in LPBF 17-4PH fabricated parts.
Proceedings Papers
HT2023, Heat Treat 2023: Proceedings from the 32nd Heat Treating Society Conference and Exposition, 121-126, October 17–19, 2023,
Abstract
View Paper
PDF
Aluminum alloy 6061 (AA6061) is widely used in industry due to its excellent formability, corrosion resistance, weldability, and strong mechanical properties after heat treatment. AA6061 is hardened through precipitation of alloying elements that act as blockers to dislocation paths in the individual aluminum grains, increasing mechanical performance. During artificial aging, these nano-scale precipitates combine and form the main hardening phase, β’’. The general heat treatment procedure for AA6061 follows a solution treatment, quench, and a direct artificial aging. The focus of this work is to develop the parameters for a materials model for AA6061 which can predict the material response to heat treatment by modeling the kinetics of precipitation formation and coarsening. This work uses data from publications found in the public domain to develop the solution kinetics, artificial aging and coarsening kinetics, and resulting mechanical properties. Another publication was used to validate the developed DANTE model by comparing hardness predictions to hardness obtained in an actual component.
Proceedings Papers
HT 2021, Heat Treat 2021: Extended Abstracts from the 31st Heat Treating Society Conference and Exposition, 76-78, September 14–16, 2021,
Abstract
View Paper
PDF
The work presented in this paper addresses a data gap that continues to be a hinderance to users of precipitation modeling tools, particularly those based on Langer-Schwartz theory. Thermodynamic and kinetic data required for precipitation models can be obtained from CALPHAD databases, but interfacial energies between the bulk and precipitate phases are not available for many alloy systems. In this work, a number of matrix-precipitate interfacial energies have been determined for influential precipitates in alloys of industrial importance, for example, carbides in Grade 22 low-alloy steels, delta phase in Ni 625 and 718, S-phase in Al 2024, and Q’ and β’’ in Al 6111.
Proceedings Papers
HT2017, Heat Treat 2017: Proceedings from the 29th Heat Treating Society Conference and Exposition, 12-18, October 24–26, 2017,
Abstract
View Paper
PDF
In industrial applications, hot forging of aluminum alloy AA 6082 is carried out at 480 °C following a preheating process in an induction heater. The forged parts are then cooled down to room temperature, heated up again to apply conventional solution treatment followed by quenching and artificial aging processes. Repetitive heating/cooling steps are a significant cause of energy loss. The aim of this study was to provide time and energy efficiency by combining hot forging and solution treatment processes in a single high temperature process. To achieve this a new and improved heat treatment pattern was introduced. AA6082 parts were quenched immediately from a rather high forging temperature and artificially aged without any necessity for a second heating step and solution treatment. Mechanical properties of parts heat treated by this new pattern were than compared to the mechanical properties of parts heat treated conventionally. Heat treatment of AA6082 alloys were carried out for 30 minutes at three different temperatures (480, 510 and 540 °C) for comparison, followed by forging, water quenching and artificial aging (180°C, 8h). Mechanical properties of each sample were investigated using hardness and tensile tests. Elemental analysis and microstructural characterization were carried out using Energy Dispersive Spectrometry (EDS), Scanning Electron Microscope (SEM) and Optical Microscope (OM). Required minimum hardness for the samples after heat treatment was considered as 90 HB. This hardness value could not be obtained for the parts forged/solution treated at 480°C and 510°C. Hardness values of parts heat treated at 540°C, water quenched and aged at 180°C were higher than 90 HB.
Proceedings Papers
HT2017, Heat Treat 2017: Proceedings from the 29th Heat Treating Society Conference and Exposition, 297-301, October 24–26, 2017,
Abstract
View Paper
PDF
Steels hardened by copper precipitation are the focus of many research programs. Most of this effort is devoted to development of low-carbon steels. Precipitation strengthening of ferrite is used for steel strengthening without losing the capability of deep drawing before the precipitation hardening. This article shows the results of precipitation strengthening in low alloyed steel containing 0.2% carbon. The steel composition is aimed at developing weldable high-strength steel for demanding structural applications. Copper precipitation was exploited to strengthen different types of microstructures. Quenching and ageing and isothermal austenite decomposition into bainite were used to develop copper precipitation. Mechanical properties and microstructure were compared. Tensile tests were performed and hardness was measured. Copper precipitation was documented by FEG SEM microscopy.
Proceedings Papers
HT2017, Heat Treat 2017: Proceedings from the 29th Heat Treating Society Conference and Exposition, 380-386, October 24–26, 2017,
Abstract
View Paper
PDF
Performances of quenchants have been enhanced and maintained based on their cooling characteristics determined by specific test systems. A rotary-arm type test system with a small ball probe has been developed for this purpose by making prototypes. Its unique concept derived mainly from a circular motion of a small ball probe in quenchants was proposed by Tawara in 1941. The prototypes have been realized by current heating, measuring and mechatronics techniques. Finally the probe material has been changed from nickel alloy to platinum for resolving the discoloration and thermal aging problems on the probe surface. The performance of the prototypes has been verified by systematic tests using specific quenchants under various cooling conditions.
Proceedings Papers
HT2015, Heat Treat 2015: Proceedings from the 28th Heat Treating Society Conference, 94-98, October 20–22, 2015,
Abstract
View Paper
PDF
The use of aluminum alloys in automotive and other industries is due to their excellent combination of weight and strength, which is obtained by heat treating. The alloying elements are put in solution by holding the material at a high temperature, and cooling at a rate fast enough to allow them to remain in solution; strengthening is then produced by the precipitation of particles of different size, shape and nature. This work presents the results of the analyses of samples made from cast aluminum alloys hardened by either the precipitation of Mg 2 Si or Al 2 Cu and of an alloy that has both. The samples were solution treated at temperatures adequate for the different alloys and cooled by placing them in water close to boiling. Aging was conducted at two different temperatures (170 and 240°C) in all cases for times as long as 100 hrs. Changes due to aging were documented by microhardeness, microscopical examination and by X-ray diffraction. X-ray examination showed that the peak corresponding to the {311} position shifts the aging condition, indicating changes in the lattice parameter of aluminum, which depends on the type of particle that precipitates.
Proceedings Papers
HT2015, Heat Treat 2015: Proceedings from the 28th Heat Treating Society Conference, 299-301, October 20–22, 2015,
Abstract
View Paper
PDF
Temperature Processing Inc. has offered merchant heat treating in the northern NJ town of North Arlington for over 60 years. Their 10,000 sq ft facility, expanded in 1998, offers broad thermal processing capability in a compact plant. Diverse services offered include annealing, tempering, bright hardening, ageing and nitriding.
Proceedings Papers
HT2015, Heat Treat 2015: Proceedings from the 28th Heat Treating Society Conference, 358-364, October 20–22, 2015,
Abstract
View Paper
PDF
This paper presents the results of an experimental investigation of the effect of three types of post-heat treatments: 1) solution treatment and aging, 2) stress relieving, and 3) annealing on the corrosion behavior of Ti-6Al-4V fabricated via direct metal laser sintering (DMLS). The microstructure and phase evolution as affected by heat treatment temperature were examined through scanning electron microscopy and via x-ray diffraction. The Vicker’s microhardness, as it was affected by various heat treatments, was compared. The corrosion behavior of the specimens was measured electrochemically in simulated body fluid at 37°C. It was found that the nonequilibrium α’ phase with a small amount of β nuclei was formed in the as-fabricated sample. Heat treatments allow the formation of the β phase and the agglomeration of β precipitates to occur at elevated temperatures. Transformed β phase with various morphologies was observed as a result of the heat treatments. Different degrees of improvement in the corrosion resistance were observed in the solution-treated and aged samples, 650 °C stress relieved, and annealed samples.
Proceedings Papers
HT2015, Heat Treat 2015: Proceedings from the 28th Heat Treating Society Conference, 431-435, October 20–22, 2015,
Abstract
View Paper
PDF
A precipitation hardenable semi-austenitic stainless steel AISI 632 grade was austenitized according to industrial specifications and thereafter subjected to isothermal treatment at sub-zero Celsius temperatures. During treatment, austenite transformed to martensite. The isothermal austenite-to-martensite transformation was monitored in situ by magnetometry and data was used to sketch a TTT diagram for transformation. As an alternative treatment, after austenitization the material was immersed in boiling nitrogen and up-quenched to room temperature by immersion in water prior to be subjected to isothermal treatment. Magnetometry showed that the additional thermal step in boiling nitrogen yields a minor increment of the fraction of martensite, but has a noteworthy accelerating effect on the transformation kinetics, which more pronounced when the isothermal holding is performed at a higher temperature. Data is interpreted in terms of instantaneous nucleation of martensite during cooling followed by time dependent growth during isothermal holding.
Proceedings Papers
Luiz Carlos Casteletti, Fábio Edson Mariani, Amadeu Lombardi Neto, André Itman Filho, George Edward Totten
HT2015, Heat Treat 2015: Proceedings from the 28th Heat Treating Society Conference, 706-710, October 20–22, 2015,
Abstract
View Paper
PDF
Precipitation-hardening stainless steels are iron-nickel chromium alloys containing precipitation hardening elements such as aluminum, titanium, niobium and copper. In this work, heat treatment of a novel precipitation hardening stainless steel using niobium as a forming element for the hardening precipitates in order to increase its surface hardness and wear resistance was performed. The steel composition was 0.03C - 0.22Si - 17.86Cr - 3.91Ni - 2.19Mo - 1.96Nb (in wt%). The samples were solubilized at 1100 °C for 2 hours. Cooling was done in oil and the samples were subsequently aged at 500, 550 and 600 °C. The solubilized samples exhibited an average hardness of 30 HRc and after the aging treatments, the hardness increased to 46 HRc. The hardness increases during the aging treatments were very fast. A 5 minute treatment achieved hardness levels that were close to the maximum obtained for this alloy. Niobium was an efficient precipitation hardeners forming a Laves phase of the type Fe 2 Nb.
Proceedings Papers
HT2011, Heat Treating 2011: Proceedings from the 26th Heat Treating Society Conference, 199-204, October 31–November 2, 2011,
Abstract
View Paper
PDF
The high-strength aluminum alloy V92Zr, part of the Al-Zn-Mg system, is a self-quenched alloy. Its primary alloying elements include 4.2 wt% Mg, 3.2 wt% Zn, 0.6 wt% Mn, and 0.15 wt% Zr. The most suitable filler wires for welding this alloy are V92W, AMg6, AMg4Zr, and No.11 (Al-Zn-Mg). This alloy is applicable in aircraft production. Prolonged heating at 50-70°C can lead to significant structural changes in the precipitation hardening of aluminum alloys due to the transition from zone aging to phase aging. Studies indicate that zone aging of Al-Zn-Mg alloys, particularly in weld seams, with repeated heating at 50-70°C, substantially increases strength while reducing elongation, cross-sectional area reduction, toughness, stress corrosion resistance, and increasing susceptibility to cracking. Research has shown that even heating at temperatures below the phase aging threshold can significantly alter the properties. This article examines the effects of prolonged low-temperature heating on the mechanical properties, crack sensitivity in impact bending, and corrosion resistance of semi-finished products and weldments of V92Zr aluminum alloys after solution treatment and aging at room and elevated temperatures.
Proceedings Papers
HT2011, Heat Treating 2011: Proceedings from the 26th Heat Treating Society Conference, 295-300, October 31–November 2, 2011,
Abstract
View Paper
PDF
There is considerable interest in nitriding austenitic stainless steels under conditions where nitrogen is primarily in solid solution. Supersaturation with nitrogen significantly increases hardness and induces high residual compressive stresses. This paper explores the relationship between nitrogen content, layer morphology, and properties. It examines Nitrex’s Nano-S nitriding processes performed at various times to achieve different nitrogen levels in austenitic AISI 304 stainless steel. The research also includes 410 grade martensitic stainless steel and 17-4 precipitation-hardened steel, with results yet to be determined. Based on these results, optimal nitriding conditions to achieve the desired properties will be recommended.