Influence Of Various Heat Treatments Research Articles

Influence of Various Heat Treatments on Microstructures and Mechanical Properties of GH4099 Superalloy Produced by Laser Powder Bed Fusion.

The microstructures and mechanical properties of a γ'-strengthened nickel-based superalloy, GH4099, produced by laser powder bed fusion, at room temperature and 900 °C are investigated, followed by three various heat treatments. The as-built (AB) alloy consists of cellular/dendrite substructures within columnar grains aligning in <100> crystal orientation. No γ' phase is observed in the AB sample due to the relatively low content of Al +Ti. Following the standard solid solution treatment, the molten pool boundaries and cellular/dendrite substructures disappear, whilst the columnar grains remain. The transformation of columnar grains to equiaxed grains occurs through the primary solid solution treatment due to the recovery and recrystallization process. After aging at 850 °C for 480 min, the carbides in the three samples distributed at grain boundaries and within grains and the spherical γ' phase whose size is about 43 nm ± 16 nm develop in the standard solid solution + aging and primary solid solution + aging samples (SA and PA samples) while the bimodal size of cubic (181 nm ± 85 nm) and spherical (43 nm ± 16 nm) γ' precipitates is presented in the primary solid solution + secondary solid solution + aging sample (PSA samples). The uniaxial tensile tests are carried out at room temperature (RT) and 900 °C. The AB sample has the best RT ductility (~51% of elongation and ~67% of area reduction). Following the three heat treatments, the samples all acquire excellent RT tensile properties (>750 MPa of yield strengths and >32% of elongations). However, clear ductility dips and intergranular fracture modes occur during the 900 °C tensile tests, which could be related to carbide distribution and a change in the deformation mechanism.

Effect of silver and heat treatment on properties of 03Kh17N10M2 austenitic steel wire

The article examines the influence of various heat treatments, their temperature, as well as silver alloying on mechanical properties, phase composition and structure of steel wire from chromium-nickel-molybdenum austenitic stainless steel 03Kh17N10M2. Choice of the amount of silver alloying was based on previous studies of the antibacterial effect of modifying medical steels with silver. Since the antibacterial effect was confirmed on several bacterial strains, for the most efficient operation of alloys, it is necessary to determine the best temperature mode for working with them. Steel for the study was smelted and then transformed into wire through rolling, forging and drawing operations. On the obtained wire samples of different diameters with a silver content (0; 0.2 and 0.5 wt. %) mechanical tests were carried out to determine the elongation, yield strength and tensile strength. Various modes and temperatures of heat treatment were tested on wire of different diameters to study their effect on mechanical properties and structure. Microstructure of the wire samples subjected to heat treatment and obtained after drawing was investigated. A phase analysis was also carried out to determine the effect of silver in various quantities on austenitic steel. According to the results of the phase composition analysis, it was concluded that silver reduces the amount of gamma phase in steel, and this effect increases in proportion to the increase in silver amount. This change correlates with a slight drop in the metal ductility. At the same time, there are no significant changes in the strength characteristics and microstructure from the presence of silver.

Effect of austenite fraction and stability on strength-hardening-ductility in additively manufactured 17-4 PH stainless steel containing nitrogen

Additively-manufactured (AM) 17-4 precipitation-hardening (PH) martensitic stainless steel (SS) built from nitrogen-atomized powder often retains a large volume fraction of austenite. The retained austenite lowers the yield strength compared to both wrought and AM 17-4 SS built from argon-atomized powder, hindering its use in many applications. However, retained austenite allows for high work hardening and high ductility through deformation-induced martensitic transformation (DIMT). This work systematically investigates the influence of various heat treatments on the volume fraction and stability of the retained austenite from tensile loading in AM 17-4 SS containing a mass fraction of 0.13% nitrogen (AM 17-4N SS). Synchrotron-based high-energy x-ray diffraction (HEXRD) is used to quantify the austenite volume fraction resulting from the heat treatments and the extent of DIMT in tensile specimens loaded to various plastic strains and specimens loaded to fracture. We show that by altering the volume fraction and stability of the retained austenite in AM 17-4N SS using different heat treatments, the DIMT process can be utilized to vary the strength, work hardening, and ductility, thus enabling its use in a wide range of applications. The AM 17-4N SS is also shown to meet or exceed the peak aged requirements for wrought 17-4 SS with yield strength (YS) of >1200 MPa, an ultimate tensile strength (UTS) of >1500 MPa, and a uniform elongation of ≥13% while retaining ≈ 20% volume fraction of austenite.

Influence of various heat treatments on fatigue crack growth in 42CrMo4 steel under mixed modes I + II and I + III

The article addresses the results of the study of the examination of fatigue fracture in mixed and I + II and I + III modes in heat treated steel 42CrMo4. Three types of thermal treatments were performed, each caused various mechanical properties of the material. Tests were performed on two sample types: compact tension specimen (CTS) and rectangular cross-sectional samples for mixed mode and I + III. Mixed mode I + II tests were performed for 30 and 60° load angles while the mixed mode test I + III was carried out for 30 and 45°. In addition, the paper shows crack paths for all cases tested. Presented research aims to expand the knowledge of fatigue crack development under mixed mode while taking into consideration different mechanical properties of the same composition-wise material. The aforementioned knowledge is a significant contribution to defining the material fatigue under complex load, independently to sample geometry and number of other limitations.

Influence of Various Heat Treatments on Hardness and Impact Strength of Uddeholm Balder: Cr-Mo-V-Ni Novel Steel Used for Engine Construction.

The construction of an engine requires optimized geometry and superb material properties in various environments. Tensile and yield strength are not the only parameters essential to consider. Hardness, impact toughness, and ductile-brittle transition temperature (DBTT) are also crucial. In this paper, Balder, Chromium-Molybdenum-Vanadium-Nickel steel with low impact toughness attested is considered. It contains both high Nickel and high Vanadium content, a rare combination among iron-based alloys. This study aims at proving that conventional heat treatment can improve its impact toughness while maintaining hardness level, exceeding its to-date performance. Steel’s exact elemental composition was checked, and material samples’ hardness and impact toughness were measured. Four heat treatments were proposed, then hardness and impact toughness were measured again. It was established that impact toughness over three times higher than marketed (57.3 J against 17 J) can be achieved with simultaneous 2 HRC points (from 46.4 HRC to 48.4 HRC) rise in hardness. Achieved parameters place examined alloy at the high-ranking position among similar steels. Occurrence of temper embrittlement was avoided. Notably, the ductile-brittle transition was not observed in any sample.

Microstructure and Residual Stress Evolution of Laser Powder Bed Fused Inconel 718 under Heat Treatments

The current work aimed to study the influence of various heat treatments on the microstructure, hardness, and residual stresses of Inconel 718 processed by laser powder bed fusion process. The reduction in residual stresses is crucial to avoid the deformation of the component during its removal from the building platform. Among the different heat treatments, 800 °C kept almost unaltered the original microstructure, reducing the residual stresses. Heat treatments at 900, 980, and 1065 °C gradually triggered the melt pool and dendritic structures dissolution, drastically reducing the residual stresses. Heat treatments at 900 and 980 °C involved the formation of δ phases, whereas 1065 °C generated carbides. These heat treatments were also performed on components with narrow internal channels revealing that heat treatments up to 900 °C did not trigger sintering mechanisms allowing to remove the powder from the inner channels.

The effect of heat treatments on pure and potassium doped drawn tungsten wires: Part I - Microstructural characterization

Advanced tungsten fiber-reinforced composites (Wf/W), showing pseudo ductile behaviour even at room temperature, are a promising option for future fusion reactors as the intrinsic brittleness of tungsten can be mitigated effectively. The drawn tungsten wires used as reinforcements are the key components of the composites, thus their mechanical properties and thermal stability define the allowed operation/fabrication temperature of the composite material itself. In this work, a comprehensive characterization of the pure and potassium doped tungsten wires was performed, focusing on the influence of various heat treatments on different microstructural features (nature of grain boundaries, grain shape and size, texture analyses) and mechanical properties. Annealing in the temperature range from 900 to 1600 °C enables the investigation of the microstructural stability of the two materials and arising annealing phenomena – recovery, recrystallization and grain growth. The results demonstrate that the pure tungsten recrystallizes fully in the temperature range 1300–1500 °C accompanied with tremendous coarsening and a complete loss of the initial fibrous, elongated grain structure. In contrast to this, potassium doped wire shows superior high temperature properties, where the performed heat treatments cause only milder microstructural changes, consequently suppressing recrystallization and grain growth to temperatures well above the investigated ones. Furthermore, hardness measurements and observed softening complement the discussion of the grain morphology evolution.

Substitution of Rare Earths in Magnesium Alloys

Magnesium alloys containing rare earth elements have better properties in terms of of formability, strength and corrosion resistance. Due to the tight supply situation these elements should be partially or complete substituted, for example by calcium. Microstructural studies of casted alloys of new compositions, and the influence of various heat treatments on their microstructure are investigated. The mechanical properties of the rolled materials are also presented and discussed. The works presented in this paper are results of the ongoing BMBF project SubSEEMag.

Research on change of phase transformation temperatures and electrical resistance triggered by heat treatment of alloy from Cu–Mn system

This paper is aimed at studying influence of various heat treatments on transformation temperatures and electrical resistance properties of alloys from binary Cu–Mn system. It was noticed that with an increase in sample’s grain size, transformation temperatures also increased. The activation energies of samples were calculated according to Kissinger and Augis–Bennett. Thermogravimetric and differential thermal analysis measurements were used to investigate phase transformations and kinetic parameters. The electrical values of resistance of alloy were investigated at different temperatures. The resistance as a function of quenching temperature showed a decrease. Depending on quenching techniques, Cu–Mn alloy can display different product phases such as parent phase and precipitation.

On the role of twinning during room temperature deformation of γ-TiAl based alloys

The present work dealing with the micromechanical modeling of the deformation behavior of γ-TiAl based alloys is based on a strong interaction between numerical simulation facilities and detailed experimental investigations. Main attention is devoted to a near-γ microstructure which exhibits equiaxed γ-grains and α 2-phase located at grain boundaries and triple junctions. The purpose is an investigation of the deformation mechanisms of polycrystalline near-γ material using both computational finite element simulations and acoustic emission (AE) measurements. A three-dimensional micromechanical model, initially developed to describe lamellar γ-TiAl, has been adjusted to simulate the deformation behavior of polycrystalline near-γ material. The contribution of deformation twinning to the total plastic deformation is computed investigating compression tests at room temperature. Concerning the onset of twinning the results of our simulation are compared with experimental data obtained from AE measurements. Investigations of the influence of various heat treatments on the twinning evolution during loading at room temperature were carried out. The deformation mechanisms were analyzed using optical microscopy, SEM and TEM.

Influence of various heat treatments on the microstructure of polycrystalline IN738LC

IN738LC is a modern, nickel-based superalloy utilized at high temperatures in aggressive environments. Durability of this superalloy is dependent on the strengthening of γ′ precipitates. This study focuses on the microstructural development of IN738LC during various heat treatments. The 1120 °C/2 h/accelerated air-cooled (AAC) solution treatment, given in the literature, already produces a bimodal precipitate microstructure, which is, thus, not an adequate solutionizing procedure to yield a single-phase solid solution in the alloy at the outset. However, the 1235 °C/4 h/water quenched (WQ) solution treatment does produce the single-phase condition. A microstructure with fine precipitates develops if solutionizing is carried out under 1200 °C/4 h/AAC conditions. Agings at lower temperatures after 1200 °C/4 h/AAC or 1250 °C/4 h/AAC or WQ conditions yield analogous microstructures. Agings below ∼950 °C for 24 hours yield nearly spheroidal precipitates, and single aging for 24 hours at 1050 °C or 1120 °C produces cuboidal precipitates. Two different γ′ precipitate growth processes are observed: merging of smaller precipitates to produce larger ones (in duplex precipitate-size microstructures) and growth through solute absorption from the matrix. Average activation energies for the precipitate growth processes are 191 and 350 kJ/mol in the ranges of 850 °C to 1050 °C and 1050 °C to 1120 °C, respectively, calculated using the precipitate sizes from microstructures in the WQ condition, and 150 and 298 kJ/mol in the analogous temperature ranges, calculated from precipitate sizes in the microstructures in the slow furnace-cooled condition.

Bonding by hot extrusion of Incoloy 825 and Duplex 2205 to low alloy steel

Low alloy AISI 4130 steel has been bonded to an Incoloy 825 and a Duplex 2205 stainless steel by an industrial hot extrusion process, the final product being a seamless clad tube, with an internal lining of these corrosion resistant alloys. The microstructures of the as processed products have been analysed using optical metallography and scanning (SEM) and scanning transmission (STEM) electron microscopy. The interdiffusion of various elements through the interface has been determined using microanalysis both in the SEM and the STEM. For the combination AISI 4130–Incoloy 825, a region close to the original interface on the Incoloy side is observed, in which a deformation substructure with subgrains, dislocations, and a considerable number of M23C6 type carbides is found. Various layers of austenite free of carbides, martensite, and ferrite–pearlite are observed on the steel side. For the combination AISI 4130–Duplex 2205, a region close to the interface, having a small amount of ferrite and a profusion of M23C6 carbides precipitated at the grain boundaries, is observed; this is succeeded by regions having a greater amount of ferrite at grain boundaries until the original structure of the Duplex is attained. The influence of various heat treatments, consisting of quenching plus tempering of the region around the bonding, has also been analysed.MST/1325

On the influence of various heat treatments and impurity additions on structure changes in Al‐Zn‐Mg alloys

Crystal Research and TechnologyVolume 19, Issue 10 p. 1339-1340 Article On the influence of various heat treatments and impurity additions on structure changes in Al-Zn-Mg alloys† Prof. Dr. H. Löffler, Prof. Dr. H. Löffler Pädagogische Hochschule Halle, Sektion Mathematik/Physik DDR-4020 Halle (Saale) Kröllwitzer Str. 44Search for more papers by this author Prof. Dr. H. Löffler, Prof. Dr. H. Löffler Pädagogische Hochschule Halle, Sektion Mathematik/Physik DDR-4020 Halle (Saale) Kröllwitzer Str. 44Search for more papers by this author First published: 1984 https://doi.org/10.1002/crat.2170191016 † Contribution presented on the occasion of the “Third Conference on Age-hardenable Aluminium Alloys” held from Nov 1st to 3rd, 1983, in Lindow/Mark (G.D.R.), organized by the Research Group “Aluminium Alloys” of the Pädagogische Hochschule in Ha AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume19, Issue101984Pages 1339-1340 RelatedInformation

Temper embrittlement and intergranular segregation of antimony: A quantitative analysis performed with the backscattering of energetic ions

The intergranular segregation of antimony associated with temper embrittlement in a low carbon manganese steel was quantitatively studied through the backscattering of MeV12C12+ and1214N12+ ions. The principles of the technique and its application to interface segregation problems are briefly explained and its main advantages discussed. The influence of various heat treatments was investigated and shown to strongly influence the segregation taking place in the α field. Segregation could not be detected in the γ field. The kinetics of the phenomenon in the critical range (400° to 600°C) is described. The role of the micro-structure was studied and it is shown that segregation does not occur only at the previous austenitic grain boundaries but at all the disordered high angle boundaries of the structure. The grain boundary Sb content after a reversion and a resegregation treatment was also studied. The results are interpreted in terms of a reversible type of segregation taking place entirely in the α phase.